The diode near the relay is called a freewheel diode. Its purpose is to deal with backflow of current once the EM field of the relay coil collapses while switching. This protects any connected electronics (like a transistor or MCU pin) from getting hit by this surge. Using a 1N4148 in its place is fine, as no big currents are involved. The diode on board uses what's called a MELF package, which is essentially identical to the through-hole part which you were showing. A faulty freewheel diode is likely to show up as a short, which would prevent the relay from switching.
@@DevMan98 Try reading the second comment I posted, but then I guess you are too narcissistic to realise both these comments were posted 7 months before your late response
It was useful skimming through your video before I attempted my heater element replacement on a slimline integrated Currys Essentials dishwasher which used the same heater (now £13 on ebay!) Surprisingly, the heater was easer to get to on the slimline machine as it was in the rear corner, I only had to take one side panel and a small rear panel off. On the downside, mine was attached with those single use "ear crimp" style clips. Being a hoarder that I am, I had a box of Halfords jubilee clips in my plumbing box. So future fixers be aware that new jubilee style clips may be needed. It was good to see your diagnostic approach too... a lot more thorough than some local appliance repair "experts" I've observed!
I was suffering from Vincedrawl, thank you Vince for saving me for the next hour and 20 minutes. Also, I bought some ps4 and xbox one controllers to fix because of you! I don't want a dishwasherrrrrrr!
Just finished the video awesome job! You've saved so much money, it's amazing how much you can do when you can be brave and have a go at fixing things and persevere, I love these videos
I’m going through exactly the same thing now with a different dishwasher that runs normally but doesn’t heat up. My gosh what a pain in the a** and what patience you have. I was pretty certain it was just going to be the heater element and a cheap and easy fix. But now goodness knows. Changed the circuit board for a new one about two years ago and hope it’s not that again. I’ll be opening it all up tomorrow and taking a look. Such a great video! Thank you!
@@jimstewart6720 Hey Jim, damn I’m sorry you’re going through that - I know the frustration lol. I was pretty sure with mine it was the heating element. The thermostat was fine and everything else was working. However the heating had been updated to a new one which required some effort to make it fit. Being that it was second hand and at least 10 years old I decided buy a new dishwasher and hope it will keep me free of problems for the next years as I don’t have the time to waste at the moment. I wish you good luck though. Keep us updated how you get in ;)
Shudda bought a Bosch. Still going strong after 15 years . Seriously though I love what you do. You have so much patience. I look forward to the next one .
I had a Bosch in the last house. Never gave me any problems :-) This house came with the Zanussi. If I was buying another I would get a Bosch but I am hoping this will keep going now and I have a replacement heater for when it gives up again :-)
Yeap, this was my first thought. Second thought is that if the diode has failed then a spike could zzap the chip. third thought is that that failed diode is shorting the power to the relay so it can't trigger. Remove the diode and try the circuit.
Great vid as usual Vince....Get yourself a large turkey baster and keep it handy for the next time you need to drain the dishwasher sump. Will save you a ton of time. Either that or disconnect the drain hose and lower it to below the level of the sump and let gravity do the work. Loving the content :)
Today i repaired a subwoofer with my father... there were so many shorts on the board... it was so suspicious... but my father insistet to try the woofer after changing the potentimeter... i thought if we do so... it will blow something.. but... guess what... after changeing the potentiometer the subwoofer worked like a charm... i was so confused. what ever... i love you videos. you inspired me to do the excactly the same and could revive so many dead devices with a lot of knowledge with your videos. Keep it up and i love ever second of your video. greatings from germany.
I re-watched some of your old videos and it shows how far you have come in a relatively short time. Yes ZD or DZ donates a Zener diode, a Zener diodes symbol is very similar to that of a regular diode. The Zener diode symbol has two small lines coming off the line of the normal diode symbol, these are at right angles to a normal diodes line and one of the lines goes forward the other goes backwards. The faulty diode is a small signal diode which will be used for protection. The 1N4148 diode that you replaced it with is a common small signal diode which has a forward voltage of up to 100V, which is well above the 12V for the relay. This is okay because you want the diode to blow if it gets a reverse voltage(power connected the wrong way round).
Thanks PDS, it is all the helpful comments from yourself and others that is helping me gradually learn it. I got lucky this time with the replacement diode being the correct one :-)
Boy Vince looking back on this video you sure have come a long way since this one. You can do so much more now, desolder ic's, much more confident in your approach to stuff, how you learn't so much in a few years is amazing you can do so much more, with much more confidence in your abilities, also your knowledge has increased dramatically since this video. Great to re watch your video and see how much knowledge you have gained since
I was a domestic appliance engineer back in the eighties. I worked for Philips Service. I had to do eleven jobs a day and over a hundred miles. Not many electronic boards in the appliances then. Engineers probably don't repair boards in machines now. Well done Vince but you wouldn't do many calls in a day.
They are only called engineers - they are not engineers in the internationally accepted sense of the word. They are mechanics or technicians at a stretch. Generally speaking domestic appliances are only economical to repair if done on a DIY basis.
Thank you again I have fixed my dishwasher today. I went step by step first I checked the flow through heater I found it OK. Then I tool a look at the board I found one of the relay legs burnt I mean seems that it had got hot. I rewelded it and hence it worked with me. I was going to take it to beko repair workshop tomorrow
cant find the right dishwasher video but thanks for your video and guidance it saved me a new dishwasher , i had glass in the wash pump and you showed me how to get it out and fix it thank you so much
Hey Vince, You are an inspiration to us have a go repair people. We don’t know how or what each thing does but we will sure as hell have a go at working through the problem. I bet you are like the rest of us and took apart your toys as a kid, just to see how it worked. I will never forget my first foray into getting stuck in, I took my old Walkman and wanted to power it from the plug. Boy did that go wrong quick, can’t just use two wires and hook them to the battery terminals. I am in love with your spirit and tenacity, I only recently discovered your channel but hope you never stop. You got a fan for life right here brother!
Literally have just been through the same headache with my dishwasher! This video was a perfect wingman helping me along the fault finding path! Unfortunately I don't not have the expertise, time or willpower to chase a fault through a circuit board so mine is being stripped for parts, hopefully it can go on to help someone else! Cracking video though, consider me subscribed!
nice fix vince you probably saved many people lots of money who have the same dishwasher with the way you detected the problem really enjoyed this video
Great bit of fault finding Vince I am very impressed. I also read a few comments and it appears your diode fix is fine which means your are a bloody champion and the missus should be mightily impressed by your skills and economising. 🤩😍👍
Pretty sure the diode you took out is a standard 4148 in surface mount form. Just a generic low-current device so your generic replacement (which is just there to protect the circuit downstream) will be fine (in fact it's probably a 4148 also!)
Thanks Jason J and Nigel Sollars. The one I replaced it with was a 1N4148 so it looks like this time I got really lucky. Thanks for the message as I feel more at ease now as that diode was on my mind in case it caused a problem :-)
I agree with the boys above. Educated guess and a bit of luck too always works wonders 👍👍 Now I would let ‘sleeping dogs lie’ and leave it alone!! Your soldering is getting better all the time. Remember....... practice practice practice 😉 Move on to the next video 👍 Cheers Vince
that's the back-emf suppresion diode. it's used to protect the electronics from the high voltage produced by the relay coil when it's switched off. any regular diode should work , the one you installed is perfecly fine. glad you got it working.
And the bands denote the cathode or negative side of the diode. Colors of that particular band don’t usually mean anything else. The current should flow in the direction of the arrow so if you meter it backwards it should be open.
My Hotpoint integrated dishwasher stopped heating up, so like you I went for the cheaper option and bought a heater element, sadly not the case for me, the outcome for you has been good, but I'm prepared to swap out my 14 year old dishwasher instead of swapping out or repairing the pcb Well done Vince
There are certainly a lot of things to go wrong in modern dishwashers. I still have a Kenmore dishwasher that cost me $240 in 1993 with a mechanical timer, a heater that's nothing more than a tubular element and a single motor that reverses at the end of each cycle to pump the water out. I'll keep it going as long as I can get parts.
I've learned alot from this but damn just replace the board! I would have been over it a long time ago. I could see fixing it if it was not replaceable but the time spent on this you couldn't make charging the customer. Impressed how you trouble shoot. Def subscribed.
Lol, following this step by step as I take apart my dishwasher. My jaw dropped when his heater was ok. Thankfully mine is kaput and I have ordered a replacement, I hope it’s going to work.
Great video Vince. I have a similar problem with my Beko dishwasher. I also thought it has to be the heating element so ordered one. This is b4 I watch your video. As you I checked the resistance and continuity and think it might not be the element now. I should have the one I ordered deliver by tomorrow. Then I can surely find out it is the element or not. I will update once receive parts. Once again thanks for sharing your valuable ideas.
Just started watching your channel and funnily enough we used to have the exact same model of dishwasher. It also developed the exact same fault. Although ours was annoyingly intermittent, about 1 in every 5 washes or so the heater would not work. Myself and my father spent ages trying to work out why it would do this, as Everytime we tested it would magically work obviously. In the end we had enough of trying to fix it and replaced it with a far better beko machine.
I think a medal should be given to Mrs Vince hehe I was thinking some of these vids remind me of that DIY bloke on the Kenny Everett show who shows a similar enthusiasm as it seems to go wrong :) BTW a zener should block reverse travel until it gets "accreted" at the correct voltage so can be both ways if the voltage is able to trigger the gate to open (sorry been long years since my YTS course back in early eighties)
Hi Vince. Don't bother with replacing the diode; you put a better diode than the original. The diode was probably crossing over the relay coil to prevent over-voltage due to flyback effects.
Thank you for the video, my dishwasher has stopped heating. I took it all apart and the heater element has continuity no issues. Which suggests it's still functional. I think I'll pull the circuit board and use the ebay repair service.
Because the relay moves its internal contacts using an electromagnet, which consists of a very long (but thin) coil of wire (an inductor), when the power is removed from the the coil (by the eternal circuitry, via the microcontroller) the magnetic field collapses and, consequently, momentarily induces a current into the connected circuit. The diode is connected across the input for the coil in the opposite polarity of the supply voltage, so it doesn't have any effect whilst the coil is powered, but when the power is switched off to the coil it will act as a short circuit for the induced current that results, thus protecting the other components from potentially damaging voltage spikes. As it's only used for very slow switching at 12v, pretty much any standard diode should do the trick, such as your 1N4148 diode. You correctly identified the zener diode, which is most likely being used to keep the supply voltage for the low voltage circuitry at a suitable voltage.
Second attempt at watching this one today. Fell asleep when you uploaded . Although what I have seen so far has actually been helpful . Our dishwasher tends to leave the dishes still wet and very little if any heat is generated so at the weekend I'm going to see if it's our heating element or not I'm not sure if the slim lime version we have is much different that the full size one you have but I would be interested to see how much different the control board and element are
Go on Vince, this is all decent day to day stuff other people should know! Thanks for the content bro been a sub for a while, good to see your chan blow up :)
Since an inductor (the relay coil) cannot change it's current instantly, the flyback diode provides a path for the current when the coil is switched off. Otherwise, a voltage spike will occur destroying switching transistors, Zener diode is normally blue band and normal diode is black band, the diode that you installed should work fine
Those pliers are called locking pliers or vise grips in America. Although I think vise grip is more of a generic name tied to some brand of sorts. Lol it's crazy we speak the same language but it's completely different at the same time sometimes. Lol. BTW great informative videos Vince I love your channel!
Hi, You caused the diode to blow, when you tested the relay with the 12v power supply when it was in circuit you applied 12v directly across the diode, when you tested with the positive on the anode and the negative on the Cathode (Black line end of the diode) this caused excessive current through the diode causing it to go short circuit, the reason for this diode is when the relay turns off the magnetic field from the coil in the relay collapses causing a reverse voltage (called back-emf) this voltage is then conducted by this diode preventing damage to the driver stage of the circuit. Next time you test a relay in circuit apply the positive lead to the end of the diode with the line on it (The Cathode) on the back emf diode (across the coil of the relay) and the negative to the other end of the diode this will latch the relay without damage to this diode. Virtually any diode will work across a relay it is simply a protection device. By the way you mention uF for capacitors the U is actually Micro so if you see symbol 'µ' 22 this means the capacitor has a rating of 22 micro farads {0.000001 farads} (the symbol 'µ' means micro), named after the famous Englishman from London Michael Faraday who made huge contributions to our knowledge of magnetism and electromagnetism at the start of the 19th century (1791-1867) Keep up the great work I enjoy watching your channel.
Thanks Tony, hopefully I will remember in future to put the + to the Cathode, I didn't know this. In this instance the diode was already shorted before I took apart the machine but if it wasn't then I now understand that 12V in the wrong polarity would have killed the diode. Thanks for the helpful tips, I appreciate it :-)
@@Mymatevince Hi, Sorry but I have do disagree, if you look at when you first took out the board and measured the relay at time code 32:43 you measured across the relay coil and it measured .388k ohm, this is the correct measurement for the coil and proves the diode was not short at this time, if the diode was short at this point the reading would be short circuit. Applying the 12 volts caused the diode to short. Not having a go at you because your skill set and determination are very impressive, I have spent my entire life working on this type of equipment I am now retired but I am very confident in my electronics diagnosis abilities. If you don''t believe me take a normal diode and place in across your power supply with the anode to the positive and negative to the Cathode the diode is then in forward bais with no regulation of the current this will kill the diode unless you have the current limiter set in the regulated power supply. When a voltage is applied in the opposite direction with the positive voltage on the Cathode (Black line) the diode is then in a reverse bias condition and no current will flow. PS don't feel bad because I have done far more accidental damage than short a diode... Cheers Tony
@@tonycross8101 Thanks Tony, I am going to try this right now with one of those 1N4148 (think that was it) to see if my power supply cuts the voltage in time before blowing the diode. The confusing thing for me is if I did blow the diode then what was the original fault. I will message back in 15 mins or so :-)
@@tonycross8101 Hi Tony, this is getting interesting!!! So I am using a 1N4148 diode and the Ohm reading before doing anything is red lead to Cathode, black lead to Anode is OL but when red lead to Anode, black to cathode it is 1.93MOhms. When I apply 12V red lead(+) to cathode and 12v black lead (-) to anode the Ohm reading is the same as above BUT..... when I swap the polarity and apply 12V + to Anode like I did in the video it blows the diode and it measures 0.69Ohms in both directions!!!! it blows it instantly without any pop or fizz. So this now has me thinking what was the original fault with the dishwasher. I haven't taken out the board to measure the resistance over the relay coil but if like you say the diode was the original problem then it wouldn't be reading .38K Ohms. The dishwasher is at this moment working perfectly and before it wasn't heating up. The terminals on the heater element where attached and all the wiring was intact and tested ok for continuity!!!! Any ideas? Thanks for getting back to me on this and never be worried about upsetting me when I am wrong. It would be more upsetting for me to think I am right when I am wrong :-)
@@Mymatevince Hi, That's right the diode will blow when the positive of the power supply is on the Anode and the Negative is on the Cathode (This is the forward bias condition for the semiconductor and will allow current to flow) without a load the current will kill the diode (almost always going virtually short circuit in both directions). Some multimeters have a diode mode usually a diode marking on the dial this biases the diode on an will allow you to test what is called the forward resistance across the diode when it is biased on reversing the leads should then be open line. By the way you mentioned Zener diodes in one of your other videos, these work slightly different to a normal IN40xx diode they are what is termed an avalanche device they have the positive voltage on the Cathode and the diode only conducts when the voltage reaches the avalanche voltage which is the rated voltage for the zener, they always have a limiting resistor to prevent damage, so when fault finding them the anode may trace to ground this is normal. I thought about your method in tracing the problem and I think your logic was very sound, sometimes faults like this can be a pain to find, the only suggestion I may suggest if this problem re-occurs is to disconnect the power and try an ohm's reading from the wire that comes from the water pressure switch to the heater and the wire that supplies the other side of the heating element, you should see the coil resistance, try this before removing the heater or disturbing the wires, as it may indicate a high resistance connection, possibly caused by the heat of the heater element. The key with intermittent faults it to be very gentle and try not to disturb much while the fault is showing, sometimes easier said than done!. One of the problems with testing a circuit with a multimeter is that some faults only show themselves under load then a simple ohms test may not show the problem, if it plays up again, and because the heater is such a pain to get to: if it were mine I would run two wires from the heater connection to an external test socket, I would then make up a short test lead with a neon bulb (with a 470k resistor in series) connected to the socket, I would then run the dishwasher, You then have a visual representation to show that the 240 a/c is actually making it to the heater, you could also wire a second neon and resistor to the output from the relay, this way you have a visual confirmation that the mains is getting to the heater all the time the dish washer is running.. (Neons are good for this they consume very little and won't change the loads involved) Obviously keep this contraption away from the kids, maybe beside the machine toward the back where they can't reach, but you can see it.!! Hopefully you have repaired it and won't have to do this but it's one suggestion obviously there are lots of other techniques. best wishes Tony
great video thank you, now I'm going to see whats wrong with my Beko dishwasher that is not heating, hopefully is the heater itself that is faulty not the board
Hello Vince; Dishwasher's here in the USA, at least my dishwasher, receives it's water from the hot water supply line. ( It also has a built in heating element ). Why does your dishwasher receive water from the cold water supply line. It seems that the efficiency would be better, if you switched your dishwasher water supply to the hot water supply line. ( Let the house water heater, do the work of heating the water ). The thermostat in the dishwasher heater, should still work as intended. ( heating and maintaining water temperature inside the dishwasher ). Also, the heater should have less build-up after the same amount of time. Thanks, for another great video.
Hi Bruce, I really don't know why they are. Maybe newer ones are different. Could it be that there is more water pressure on a cold supply if it is mains fed while the hot supply pressure might be weak????? Since you have to heat up the cold water in your house anyway via a boiler I wonder is there any energy saving to be made by connecting it to the hot supply over the cold supply. I think gas is cheaper than electricity here in the UK so maybe using the hot water from the gas boiler would save money. Hopefully someone will reply who knows the answer :-)
I have not been able to find any EU regulations regarding the use of the hot or cold water supply line. For Dishwashers in the UK. However, I did find on page 14 of the manual, for your Zanussi ZDT41 dishwasher, the following. Water connection Water inlet hose Connected the appliance to a hot (max. 60°) or cold water supply. If the hot water comes from alternative sources of energy that are more environmentally friendly (e.g. solar or photovoltaic panels and aeolian), use a hot water supply to decrease energy consumption. Connect the inlet hose to a water tap with an external thread of 3/4”. The installer for your Dishwasher, did have a choice of whether to use the hot water supply or the cold. Maybe the gas, is not considered a environmentally friendly source. The electricity used to heat the dishwasher water, could come from an environmentally friendly source, for your area. Sounds like a long drawn out, unnecessary - what if video, ( to compare the two ). That I would definitely watch.
@@BruceAFairchild Interesting, I wonder if plumbers on new build properties are now installing valves on the cold and hot water supply for dishwashers so the customer has a choice. Maybe the UK will start to move over to a hot water supply in the future. Cheers for the idea of a video, I don't think I will be the one doing it as I lack the knowledge but it is still a good idea :-)
I have the same washing machine, with the same problem. But after reset it works properly for a few days, and then the water can't heat up again. I will try to change the diode first. Thnx for the video.
I just read up on Zener-diodes, and this is what I found: They differ from normal diodes because they permit voltage to go either direction (bidirectional), whereas normal diodes can only reliably permit voltage to go in *one* direction (unidirectional). Normally, the Zener-diode would not permit current in the opposite direction *until* the voltage passes the "Reverse Voltage"-limit. All Diodes have a so-called "Reverse Voltage"-specification, which specifies a voltage in which the diode *will* permit current through the opposite direction. Normal diodes cannot operate reliably above that voltage limit, Zener-diodes *can.* If a diode has shorted completely, voltage can pass through unimpeded in both directions (the diode just acts as a piece of wire). The purpose of a diode is to limit directionality (like a polarized capacitor, minus the capacitance). This directionality is also the reason why they have a black band around one of the edges, to indicate which side is "forward" (corresponding to the perpendicular line at the tip of the arrow on the board, with the arrow indicating which direction the current should flow). Hint: Diodes are also popularily called "rectifiers", as they're able to convert (limitedly) AC-current into DC-current, by chopping the negative part of the current/voltage. EDIT: Added a ton of extra info, as well as a bit of fixing here and there.
@MymateVince I love your methods.. very patient, I would of been half way through the video and said the words... “ now!, here we have my testing Hammer!” Smash, Smash, Smash!!! And yes it appears I need a new dishwasher!
Very very interesting fix and problem finder. I am actually impressed. Could you have taken the board to an electrical supplier and asked them for 'one of those please' and point to D8 lol. Firstly they may have said 'yep here is a pack of 3 for 48p. Hey are you that guy on youtube?' or they may say 'Nope we dont supply the d4j354s diodes, but we can get some in for you. Hey are you the guy from youtube?' Did you clean the limescale out from the heater? That would surely make it less efficient if it was left in. Suggestion. Do an electronic fix with Ben. Possibly even create a small fault for him to discover and teach him a skill he can take with him as he becomes an adult and starts his own repair business or gets his own YT channel.
Cheers Emma, I cleaned some of the limescale but some of it wouldn't budge, I was only scraping it with a knife though so chemicals might have worked better. I would love to teach Ben but as of now he doesn't have much interest in the stuff I do. I hope when he gets older he will get more interest. All the independent shops round here have closed a long time ago. There is a RS counter nearby so maybe they might be more knowledgeable about the different components :-)
Thanks so much Amerya. I looked for ages online and I couldn't find out this info. The one I installed was a 1N4148 so it looks like I got lucky this time as I think it is the same but with through hole legs :-) Thanks again. Vince :-)
Most diodes can be replaced with other general diodes and work, but if the diode you use to replace a faulty one can not handle the voltage and current applied to it, it will eventually fail. It should be noted diodes can fail but before they completely fail, they can exhibit strange "intermittent" behaviour especially when their environment has large temperature variations and or when the voltage is completely removed from them, allowing the discharge of the capacitance that they seem to develop, thus discharging the capacitance apparently resets them. Having said that I would mark the date you replaced the diode and after three years if the heater hasn't failed I am pretty confident you may have actually turned a Factory Lemon or a refurbished Dish washer into a proper "Factory specified" functioning Dishwasher.. TIME WILL TELL... As Usual I dropped you a Like Vince,
This kept me occupied for a while. Was a bit drastic removing the microprocessor for the sake of a s/c surface mount (SMD) LL1N4148 diode. I hope your Zanussi is still washing dishes ok?. It used to be the appliance of science in my day before I moved here to Aus.
Good job well done! Maybe bare in mind the fire brigade have still got the useful speed dial number 999 lol didn't like the scorching on the pipe may turn out to be the next fire hazard after the dryers and fridges
Hi vince I haven't finished the full vid yet but just so you know you can test those relays quickly with a 9v battery and also you can click the lid off them and clean the contacts
@@Mymatevince so if I understand correctly, the reason you couldn't test the relay in circuit was because of the faulty diode across the coil, so could yiu now in theory test the relay in circuit? I'm sure last time I tested one of those relays on a washer control board I just tested it in circuit. Thanks for the vid and good job on this one, its difficult when you have little information and I love how you piece the puzzle together and solve the problem with what you have in front of you.
@@reacey Hi, yes I think that is correct. I am pretty sure if I tested the relay in circuit now I would hear it click as the faulty diode has been swapped out. You have to make sure the polarity is correct though when using your battery or power supply which I didn't do in the video :-)
Hi we have the exact same problem with our ZDT41 dishwasher, it seems to work if you leave it switched off completely at the socket for a while it seems to work again, I suspect this might have been your issue!! Also I suspect thermostats in these get stuck open and the circuit board then thinks the water is at temp. hence only cold water. Also as a side note these dishwashers do not like running with the salt light on as yours is, if we keep ours topped up it works better.
the diode across the coil is a flyback, it stops high voltage from sapping the transistor or micro controller, the zener diode is to voltage regulator in the circuit, ie if it goes over 5volts then it puts the rest to ground ::
Well done Vince. A question for the crowd. Obviously the flyback relay diode was the issue but what about all those shorts around the MCU. Is that normal?
I have taken the control panel on my dishwasher apart several times and re-flowed the solder to the main power relay. This has always restored normal service though I did buy a replacement relay last time in readiness for the next "fault". Anything more than this and I would personally just buy a new machine.
2 years late....not really sure 😂. The Diode test only should work in diode mode to drop a voltage 0.5v nominal for most standard diodes, that diode has a short as 3 ohms in both directions. For someone who appears an amateur electrics DIYer you have far more patience than me and I troubleshoot daily, good work 👏
Both diodes you took off are 1N4148. The zeners are the grey blobs. The label DZ1 is the label for the grey blob. Also, since your push buttons and LEDS still worked, your microcontroller can not be shorted. A 1N4148 is a signal diode. It should not have been used for absorbing the EMF of the relay (it's parallel on the coil of the relay). It's not made for that. It's a design mistake. If it breaks again replace it with a 1N4001. A 1N4148 is rated for 100mA. Your relay is not that small, the flyback current may exceed 100mA. A 1N4001 is rated 1A.
Great job, bro 👍 To me the diode you soldered in is ok, no need to change anymore. It doesn't have to be a smd type diode. As Christian Ivarsson and Jason J wrote already it is an ordinary protecting diode for the transistor or IC switching the relais. What wonders me is the short you measured between Vss and Vdd of that Controller IC while it was removed from the board. But mirically it is working. By the way @29:52 the word SPULE is german and means coil. The relais has a 12Vdc relais coil. I currently have a similar problem with a washing machine and wish I could fix it as you did. Like you I do not have any schematics and my boards are multilayer smd boards.
This is a supressor diode. Its supress high voltage spikes generatet by the coil in the relay in case the microcontroller switches the relay off. You can use your Replacement. It should work fine.
The diode is in parallel with the relay to protect the driver from the voltage created by the relay when it is turned off , when you turn the relay on you create an electromagnet and when you remove the voltage as the magnetic field collapses it induces a voltage in the coil you need to shunt this voltage to prevent damage to the circuit that drives the relay ( try googling diode in parallel with relay you will find a better more in depth explanation ) to feel this connect a relay to a battery (something around 5 to 12 volts) and place your fingers on the relay coil when you disconnect the battery and you will get a shock
love the simplified explanation, and the diode only goes one way to block the field when it tries to return to the circuit, after the relay turns off (normally off).
Good video, thanks. I am trying to check the continuity on the heating element but just can't see exactly where to connect the probes in the clip? Any tips?
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I just love how this man tackles all sorts of electronic devices. Good job!
Thank you :-)
The diode near the relay is called a freewheel diode. Its purpose is to deal with backflow of current once the EM field of the relay coil collapses while switching. This protects any connected electronics (like a transistor or MCU pin) from getting hit by this surge.
Using a 1N4148 in its place is fine, as no big currents are involved. The diode on board uses what's called a MELF package, which is essentially identical to the through-hole part which you were showing. A faulty freewheel diode is likely to show up as a short, which would prevent the relay from switching.
Perfect, thanks Maya :-)
I was going to respond in the same way as Maya but was beaten to it :)
Just realised how old this video is. Thought it was a new one as it just appeared in my recommended vids.
@@robertweiss4171 If only you were 3 years and 5 months faster at typing!
@@DevMan98 Try reading the second comment I posted, but then I guess you are too narcissistic to realise both these comments were posted 7 months before your late response
It was useful skimming through your video before I attempted my heater element replacement on a slimline integrated Currys Essentials dishwasher which used the same heater (now £13 on ebay!) Surprisingly, the heater was easer to get to on the slimline machine as it was in the rear corner, I only had to take one side panel and a small rear panel off. On the downside, mine was attached with those single use "ear crimp" style clips. Being a hoarder that I am, I had a box of Halfords jubilee clips in my plumbing box. So future fixers be aware that new jubilee style clips may be needed.
It was good to see your diagnostic approach too... a lot more thorough than some local appliance repair "experts" I've observed!
I was suffering from Vincedrawl, thank you Vince for saving me for the next hour and 20 minutes. Also, I bought some ps4 and xbox one controllers to fix because of you! I don't want a dishwasherrrrrrr!
119/5000
When I imagine you were worried about chip soldering more than a year ago, your progress is amazing. Super video
Thanks mate :-)
Just finished the video awesome job! You've saved so much money, it's amazing how much you can do when you can be brave and have a go at fixing things and persevere, I love these videos
Thanks mate :-)
I’m going through exactly the same thing now with a different dishwasher that runs normally but doesn’t heat up. My gosh what a pain in the a** and what patience you have. I was pretty certain it was just going to be the heater element and a cheap and easy fix. But now goodness knows. Changed the circuit board for a new one about two years ago and hope it’s not that again. I’ll be opening it all up tomorrow and taking a look. Such a great video! Thank you!
Stefano, how cid you get on with your repair? I'm in the same situation with a 6 yo Beko.
@@jimstewart6720 Hey Jim, damn I’m sorry you’re going through that - I know the frustration lol. I was pretty sure with mine it was the heating element. The thermostat was fine and everything else was working. However the heating had been updated to a new one which required some effort to make it fit. Being that it was second hand and at least 10 years old I decided buy a new dishwasher and hope it will keep me free of problems for the next years as I don’t have the time to waste at the moment. I wish you good luck though. Keep us updated how you get in ;)
Shudda bought a Bosch. Still going strong after 15 years . Seriously though I love what you do. You have so much patience. I look forward to the next one .
I had a Bosch in the last house. Never gave me any problems :-) This house came with the Zanussi. If I was buying another I would get a Bosch but I am hoping this will keep going now and I have a replacement heater for when it gives up again :-)
I think it's luck of the draw to be honest. I've had a generic Vestel-made slimline dishwasher for 11 years, and it's never given a moment's trouble.
The diode is there to prevent back-emf. Very common to stick one in any circuit were coils are used if not using mosfets with beefy internal diodes.
Yeap, this was my first thought. Second thought is that if the diode has failed then a spike could zzap the chip. third thought is that that failed diode is shorting the power to the relay so it can't trigger. Remove the diode and try the circuit.
That's what i thought as well. Specs for a replacement isn't too critical in my opinion as long as it can handle the 12V.
Great vid as usual Vince....Get yourself a large turkey baster and keep it handy for the next time you need to drain the dishwasher sump. Will save you a ton of time. Either that or disconnect the drain hose and lower it to below the level of the sump and let gravity do the work. Loving the content :)
Today i repaired a subwoofer with my father... there were so many shorts on the board... it was so suspicious... but my father insistet to try the woofer after changing the potentimeter... i thought if we do so... it will blow something.. but... guess what... after changeing the potentiometer the subwoofer worked like a charm... i was so confused. what ever... i love you videos. you inspired me to do the excactly the same and could revive so many dead devices with a lot of knowledge with your videos. Keep it up and i love ever second of your video. greatings from germany.
sorry for these many dots but i am still confused :D
I re-watched some of your old videos and it shows how far you have come in a relatively short time. Yes ZD or DZ donates a Zener diode, a Zener diodes symbol is very similar to that of a regular diode. The Zener diode symbol has two small lines coming off the line of the normal diode symbol, these are at right angles to a normal diodes line and one of the lines goes forward the other goes backwards.
The faulty diode is a small signal diode which will be used for protection. The 1N4148 diode that you replaced it with is a common small signal diode which has a forward voltage of up to 100V, which is well above the 12V for the relay. This is okay because you want the diode to blow if it gets a reverse voltage(power connected the wrong way round).
Thanks PDS, it is all the helpful comments from yourself and others that is helping me gradually learn it. I got lucky this time with the replacement diode being the correct one :-)
Was great watching you! Nice lesson for all of us who are diy lovers.
Thx for sharing
Boy Vince looking back on this video you sure have come a long way since this one. You can do so much more now, desolder ic's, much more confident in your approach to stuff, how you learn't so much in a few years is amazing you can do so much more, with much more confidence in your abilities, also your knowledge has increased dramatically since this video. Great to re watch your video and see how much knowledge you have gained since
I was a domestic appliance engineer back in the eighties. I worked for Philips Service. I had to do eleven jobs a day and over a hundred miles. Not many electronic boards in the appliances then. Engineers probably don't repair boards in machines now. Well done Vince but you wouldn't do many calls in a day.
They are only called engineers - they are not engineers in the internationally accepted sense of the word. They are mechanics or technicians at a stretch. Generally speaking domestic appliances are only economical to repair if done on a DIY basis.
Thank you again I have fixed my dishwasher today. I went step by step first I checked the flow through heater I found it OK. Then I tool a look at the board I found one of the relay legs burnt I mean seems that it had got hot. I rewelded it and hence it worked with me. I was going to take it to beko repair workshop tomorrow
cant find the right dishwasher video but thanks for your video and guidance it saved me a new dishwasher , i had glass in the wash pump and you showed me how to get it out and fix it thank you so much
Hey Vince,
You are an inspiration to us have a go repair people. We don’t know how or what each thing does but we will sure as hell have a go at working through the problem. I bet you are like the rest of us and took apart your toys as a kid, just to see how it worked. I will never forget my first foray into getting stuck in, I took my old Walkman and wanted to power it from the plug. Boy did that go wrong quick, can’t just use two wires and hook them to the battery terminals.
I am in love with your spirit and tenacity, I only recently discovered your channel but hope you never stop. You got a fan for life right here brother!
Thanks my friend, that is a nice comment to read :-)
I have been told that the inscription on my gravestone will read. "All things that are put together must come apart again". 😃
Literally have just been through the same headache with my dishwasher! This video was a perfect wingman helping me along the fault finding path!
Unfortunately I don't not have the expertise, time or willpower to chase a fault through a circuit board so mine is being stripped for parts, hopefully it can go on to help someone else!
Cracking video though, consider me subscribed!
nice fix vince you probably saved many people lots of money who have the same dishwasher with the way you detected the problem really enjoyed this video
Great bit of fault finding Vince I am very impressed. I also read a few comments and it appears your diode fix is fine which means your are a bloody champion and the missus should be mightily impressed by your skills and economising. 🤩😍👍
Haha, thanks bad ass cat :-)
Pretty sure the diode you took out is a standard 4148 in surface mount form. Just a generic low-current device so your generic replacement (which is just there to protect the circuit downstream) will be fine (in fact it's probably a 4148 also!)
I think thats a winner, doing a quick look up,
troncart.com/smd-components/65-30-pcs-smd-1n4148-switching-diode-sod-80.html
Thanks Jason J and Nigel Sollars. The one I replaced it with was a 1N4148 so it looks like this time I got really lucky. Thanks for the message as I feel more at ease now as that diode was on my mind in case it caused a problem :-)
I agree with the boys above. Educated guess and a bit of luck too always works wonders 👍👍
Now I would let ‘sleeping dogs lie’ and leave it alone!!
Your soldering is getting better all the time. Remember....... practice practice practice 😉
Move on to the next video 👍
Cheers Vince
Why the need for brackets quite pointless really?
Wow your soldering skills have improved so much from your first videos
that's the back-emf suppresion diode. it's used to protect the electronics from the high voltage produced by the relay coil when it's switched off. any regular diode should work , the one you installed is perfecly fine. glad you got it working.
And the bands denote the cathode or negative side of the diode. Colors of that particular band don’t usually mean anything else. The current should flow in the direction of the arrow so if you meter it backwards it should be open.
Thank you :-)
Definitely seems to be a normal diode from brief research I did. Excellent fix work Vince as per!
My Hotpoint integrated dishwasher stopped heating up, so like you I went for the cheaper option and bought a heater element, sadly not the case for me, the outcome for you has been good, but I'm prepared to swap out my 14 year old dishwasher instead of swapping out or repairing the pcb
Well done Vince
Thanks mate :-)
@@Mymatevince
Keep it up, I'm intrigued repairing stuff like yourself and your DIY vids are great and iinformative 👌
There are certainly a lot of things to go wrong in modern dishwashers. I still have a Kenmore dishwasher that cost me $240 in 1993 with a mechanical timer, a heater that's nothing more than a tubular element and a single motor that reverses at the end of each cycle to pump the water out. I'll keep it going as long as I can get parts.
I've learned alot from this but damn just replace the board!
I would have been over it a long time ago. I could see fixing it if it was not replaceable but the time spent on this you couldn't make charging the customer. Impressed how you trouble shoot.
Def subscribed.
Impressive patience and work.
I think I would have taken a sledgehammer to the dishwasher and just replaced it.
Enjoying this fault finding mission. Great video!
Lol, following this step by step as I take apart my dishwasher.
My jaw dropped when his heater was ok.
Thankfully mine is kaput and I have ordered a replacement, I hope it’s going to work.
The diode supresses high voltage wich every coil develops when it is turned off. So you did it right, should work forever ;-)
You are one legend what can you not fix! ❤️
Great video Vince.
I have a similar problem with my Beko dishwasher. I also thought it has to be the heating element so ordered one. This is b4 I watch your video. As you I checked the resistance and continuity and think it might not be the element now. I should have the one I ordered deliver by tomorrow. Then I can surely find out it is the element or not.
I will update once receive parts.
Once again thanks for sharing your valuable ideas.
Just started watching your channel and funnily enough we used to have the exact same model of dishwasher. It also developed the exact same fault. Although ours was annoyingly intermittent, about 1 in every 5 washes or so the heater would not work. Myself and my father spent ages trying to work out why it would do this, as Everytime we tested it would magically work obviously. In the end we had enough of trying to fix it and replaced it with a far better beko machine.
I think a medal should be given to Mrs Vince hehe I was thinking some of these vids remind me of that DIY bloke on the Kenny Everett show who shows a similar enthusiasm as it seems to go wrong :) BTW a zener should block reverse travel until it gets "accreted" at the correct voltage so can be both ways if the voltage is able to trigger the gate to open (sorry been long years since my YTS course back in early eighties)
Reg Prescott was the character.
Haha, I remember that show from when I was young. I just googled Reg Prescott, first time I seen that in over 30 years :-)
Hi Vince. Don't bother with replacing the diode; you put a better diode than the original. The diode was probably crossing over the relay coil to prevent over-voltage due to flyback effects.
Thank you for the video, my dishwasher has stopped heating. I took it all apart and the heater element has continuity no issues. Which suggests it's still functional.
I think I'll pull the circuit board and use the ebay repair service.
When an appliance breaks in your house, does your wife say, "Honey, good news! The dishwasher stopped working!".
Because the relay moves its internal contacts using an electromagnet, which consists of a very long (but thin) coil of wire (an inductor), when the power is removed from the the coil (by the eternal circuitry, via the microcontroller) the magnetic field collapses and, consequently, momentarily induces a current into the connected circuit. The diode is connected across the input for the coil in the opposite polarity of the supply voltage, so it doesn't have any effect whilst the coil is powered, but when the power is switched off to the coil it will act as a short circuit for the induced current that results, thus protecting the other components from potentially damaging voltage spikes. As it's only used for very slow switching at 12v, pretty much any standard diode should do the trick, such as your 1N4148 diode. You correctly identified the zener diode, which is most likely being used to keep the supply voltage for the low voltage circuitry at a suitable voltage.
Amazing, thanks Pete, you explain it in a way that even I understand :-)
I had something similar happen on my Bosch dishwasher, turned out the solder joints on the relays cracked, it was an easy fix.
Second attempt at watching this one today. Fell asleep when you uploaded . Although what I have seen so far has actually been helpful . Our dishwasher tends to leave the dishes still wet and very little if any heat is generated so at the weekend I'm going to see if it's our heating element or not I'm not sure if the slim lime version we have is much different that the full size one you have but I would be interested to see how much different the control board and element are
I bet they are very similar, maybe the heater has slightly less wattage. Let me know if you find a fault :-)
Go on Vince, this is all decent day to day stuff other people should know! Thanks for the content bro been a sub for a while, good to see your chan blow up :)
Thanks mate :-)
I fell asleep hard and watched Vince try to fix a dishwasher with the roof of my mouth instead of my eyes.
Haha, I have the same problem when editing these and then watching them back :-)
My heart went out to you vince on that dish washer i would have binned it. I just don't have the patience ❤😂
Since an inductor (the relay coil) cannot change it's current instantly, the flyback diode provides a path for the current when the coil is switched off. Otherwise, a voltage spike will occur destroying switching transistors, Zener diode is normally blue band and normal diode is black band, the diode that you installed should work fine
This channel is therapy for me. Haha.
Those pliers are called locking pliers or vise grips in America. Although I think vise grip is more of a generic name tied to some brand of sorts. Lol it's crazy we speak the same language but it's completely different at the same time sometimes. Lol.
BTW great informative videos Vince I love your channel!
Think locking pliers is the correct term in UK and USA, we tend to call them "mole grips" but that's a brand name like "vice grips" mate 😀
This diode will be just fine ... and again tnx for great relaxing content
Thanks :-)
Vince worried that he might have to wash the dishes by hand.
Haha, that was my main inspiration ;-)
🤣😂🤣
Ya lazy bastard. Just handwash them. Dishwashers are for the lazy idiots. 😂😂😂😂😁😁😁😁
@@AcousticAdd1ct ?
HAL would be proud of you Vince!
Hi,
You caused the diode to blow, when you tested the relay with the 12v power supply when it was in circuit you applied 12v directly across the diode, when you tested with the positive on the anode and the negative on the Cathode (Black line end of the diode) this caused excessive current through the diode causing it to go short circuit, the reason for this diode is when the relay turns off the magnetic field from the coil in the relay collapses causing a reverse voltage (called back-emf) this voltage is then conducted by this diode preventing damage to the driver stage of the circuit.
Next time you test a relay in circuit apply the positive lead to the end of the diode with the line on it (The Cathode) on the back emf diode (across the coil of the relay) and the negative to the other end of the diode this will latch the relay without damage to this diode. Virtually any diode will work across a relay it is simply a protection device.
By the way you mention uF for capacitors the U is actually Micro so if you see symbol 'µ' 22 this means the capacitor has a rating of 22 micro farads {0.000001 farads} (the symbol 'µ' means micro), named after the famous Englishman from London Michael Faraday who made huge contributions to our knowledge of magnetism and electromagnetism at the start of the 19th century (1791-1867)
Keep up the great work I enjoy watching your channel.
Thanks Tony, hopefully I will remember in future to put the + to the Cathode, I didn't know this. In this instance the diode was already shorted before I took apart the machine but if it wasn't then I now understand that 12V in the wrong polarity would have killed the diode. Thanks for the helpful tips, I appreciate it :-)
@@Mymatevince Hi, Sorry but I have do disagree, if you look at when you first took out the board and measured the relay at time code 32:43 you measured across the relay coil and it measured .388k ohm, this is the correct measurement for the coil and proves the diode was not short at this time, if the diode was short at this point the reading would be short circuit. Applying the 12 volts caused the diode to short.
Not having a go at you because your skill set and determination are very impressive, I have spent my entire life working on this type of equipment I am now retired but I am very confident in my electronics diagnosis abilities. If you don''t believe me take a normal diode and place in across your power supply with the anode to the positive and negative to the Cathode the diode is then in forward bais with no regulation of the current this will kill the diode unless you have the current limiter set in the regulated power supply. When a voltage is applied in the opposite direction with the positive voltage on the Cathode (Black line) the diode is then in a reverse bias condition and no current will flow. PS don't feel bad because I have done far more accidental damage than short a diode... Cheers Tony
@@tonycross8101 Thanks Tony, I am going to try this right now with one of those 1N4148 (think that was it) to see if my power supply cuts the voltage in time before blowing the diode. The confusing thing for me is if I did blow the diode then what was the original fault. I will message back in 15 mins or so :-)
@@tonycross8101 Hi Tony, this is getting interesting!!! So I am using a 1N4148 diode and the Ohm reading before doing anything is red lead to Cathode, black lead to Anode is OL but when red lead to Anode, black to cathode it is 1.93MOhms.
When I apply 12V red lead(+) to cathode and 12v black lead (-) to anode the Ohm reading is the same as above BUT..... when I swap the polarity and apply 12V + to Anode like I did in the video it blows the diode and it measures 0.69Ohms in both directions!!!! it blows it instantly without any pop or fizz. So this now has me thinking what was the original fault with the dishwasher. I haven't taken out the board to measure the resistance over the relay coil but if like you say the diode was the original problem then it wouldn't be reading .38K Ohms. The dishwasher is at this moment working perfectly and before it wasn't heating up. The terminals on the heater element where attached and all the wiring was intact and tested ok for continuity!!!! Any ideas? Thanks for getting back to me on this and never be worried about upsetting me when I am wrong. It would be more upsetting for me to think I am right when I am wrong :-)
@@Mymatevince Hi, That's right the diode will blow when the positive of the power supply is on the Anode and the Negative is on the Cathode (This is the forward bias condition for the semiconductor and will allow current to flow) without a load the current will kill the diode (almost always going virtually short circuit in both directions). Some multimeters have a diode mode usually a diode marking on the dial this biases the diode on an will allow you to test what is called the forward resistance across the diode when it is biased on reversing the leads should then be open line.
By the way you mentioned Zener diodes in one of your other videos, these work slightly different to a normal IN40xx diode they are what is termed an avalanche device they have the positive voltage on the Cathode and the diode only conducts when the voltage reaches the avalanche voltage which is the rated voltage for the zener, they always have a limiting resistor to prevent damage, so when fault finding them the anode may trace to ground this is normal.
I thought about your method in tracing the problem and I think your logic was very sound, sometimes faults like this can be a pain to find, the only suggestion I may suggest if this problem re-occurs is to disconnect the power and try an ohm's reading from the wire that comes from the water pressure switch to the heater and the wire that supplies the other side of the heating element, you should see the coil resistance, try this before removing the heater or disturbing the wires, as it may indicate a high resistance connection, possibly caused by the heat of the heater element. The key with intermittent faults it to be very gentle and try not to disturb much while the fault is showing, sometimes easier said than done!.
One of the problems with testing a circuit with a multimeter is that some faults only show themselves under load then a simple ohms test may not show the problem, if it plays up again, and because the heater is such a pain to get to: if it were mine I would run two wires from the heater connection to an external test socket, I would then make up a short test lead with a neon bulb (with a 470k resistor in series) connected to the socket, I would then run the dishwasher, You then have a visual representation to show that the 240 a/c is actually making it to the heater, you could also wire a second neon and resistor to the output from the relay, this way you have a visual confirmation that the mains is getting to the heater all the time the dish washer is running.. (Neons are good for this they consume very little and won't change the loads involved) Obviously keep this contraption away from the kids, maybe beside the machine toward the back where they can't reach, but you can see it.!!
Hopefully you have repaired it and won't have to do this but it's one suggestion obviously there are lots of other techniques.
best wishes
Tony
59:48 "My wife wants the dishwasher working again"? We believe you Vince lol
great video thank you, now I'm going to see whats wrong with my Beko dishwasher that is not heating, hopefully is the heater itself that is faulty not the board
Hello Vince;
Dishwasher's here in the USA, at least my dishwasher, receives it's water from the hot water supply line. ( It also has a built in heating element ).
Why does your dishwasher receive water from the cold water supply line. It seems that the efficiency would be better, if you switched your dishwasher water supply to the hot water supply line. ( Let the house water heater, do the work of heating the water ). The thermostat in the dishwasher heater, should still work as intended. ( heating and maintaining water temperature inside the dishwasher ). Also, the heater should have less build-up after the same amount of time.
Thanks, for another great video.
Hi Bruce, I really don't know why they are. Maybe newer ones are different. Could it be that there is more water pressure on a cold supply if it is mains fed while the hot supply pressure might be weak????? Since you have to heat up the cold water in your house anyway via a boiler I wonder is there any energy saving to be made by connecting it to the hot supply over the cold supply. I think gas is cheaper than electricity here in the UK so maybe using the hot water from the gas boiler would save money. Hopefully someone will reply who knows the answer :-)
EU regulation .
I have not been able to find any EU regulations regarding the use of the hot or cold water supply line. For Dishwashers in the UK. However, I did find on page 14 of the manual, for your Zanussi ZDT41 dishwasher, the following.
Water connection
Water inlet hose Connected the appliance to a hot (max. 60°) or cold water supply. If the hot water comes from alternative sources of energy that are more environmentally friendly (e.g. solar or photovoltaic panels and aeolian), use a hot water supply to decrease energy consumption. Connect the inlet hose to a water tap with an external thread of 3/4”.
The installer for your Dishwasher, did have a choice of whether to use the hot water supply or the cold.
Maybe the gas, is not considered a environmentally friendly source. The electricity used to heat the dishwasher water, could come from an environmentally friendly source, for your area.
Sounds like a long drawn out,
unnecessary - what if video, ( to compare the two ).
That I would definitely watch.
@@BruceAFairchild Interesting, I wonder if plumbers on new build properties are now installing valves on the cold and hot water supply for dishwashers so the customer has a choice. Maybe the UK will start to move over to a hot water supply in the future. Cheers for the idea of a video, I don't think I will be the one doing it as I lack the knowledge but it is still a good idea :-)
Very nice work Vince, your tenacity is an inspiration!
Thanks :-)
The diode near the relay is used to pass the high voltage produced across the coil in the relay as it switches off .
Super. Gripping stuff Vince. I was so worried for u when u started into the control board 😱😂😂
Next video: Bought this faulty house on Ebay for repair
i wud love to see that
I have the same washing machine, with the same problem. But after reset it works properly for a few days, and then the water can't heat up again.
I will try to change the diode first. Thnx for the video.
*lol Is it bad i enjoy when Vince gets worried.. HeHE!!!*
I just read up on Zener-diodes, and this is what I found:
They differ from normal diodes because they permit voltage to go either direction (bidirectional), whereas normal diodes can only reliably permit voltage to go in *one* direction (unidirectional). Normally, the Zener-diode would not permit current in the opposite direction *until* the voltage passes the "Reverse Voltage"-limit.
All Diodes have a so-called "Reverse Voltage"-specification, which specifies a voltage in which the diode *will* permit current through the opposite direction. Normal diodes cannot operate reliably above that voltage limit, Zener-diodes *can.*
If a diode has shorted completely, voltage can pass through unimpeded in both directions (the diode just acts as a piece of wire). The purpose of a diode is to limit directionality (like a polarized capacitor, minus the capacitance). This directionality is also the reason why they have a black band around one of the edges, to indicate which side is "forward" (corresponding to the perpendicular line at the tip of the arrow on the board, with the arrow indicating which direction the current should flow).
Hint: Diodes are also popularily called "rectifiers", as they're able to convert (limitedly) AC-current into DC-current, by chopping the negative part of the current/voltage.
EDIT: Added a ton of extra info, as well as a bit of fixing here and there.
Thanks for the detailed explanation. Nice one :-)
Well done Vince, the sure did apply some science to that Zanussi.
I’ve been binging all of your videos
Congrats Vince :)). Maybe make a video on repairing Bluetooth speakers think the batteries go on them probably just need replacing
@MymateVince I love your methods.. very patient, I would of been half way through the video and said the words... “ now!, here we have my testing Hammer!” Smash, Smash, Smash!!! And yes it appears I need a new dishwasher!
Very very interesting fix and problem finder. I am actually impressed.
Could you have taken the board to an electrical supplier and asked them for 'one of those please' and point to D8 lol. Firstly they may have said 'yep here is a pack of 3 for 48p. Hey are you that guy on youtube?' or they may say 'Nope we dont supply the d4j354s diodes, but we can get some in for you. Hey are you the guy from youtube?'
Did you clean the limescale out from the heater? That would surely make it less efficient if it was left in.
Suggestion. Do an electronic fix with Ben. Possibly even create a small fault for him to discover and teach him a skill he can take with him as he becomes an adult and starts his own repair business or gets his own YT channel.
Cheers Emma, I cleaned some of the limescale but some of it wouldn't budge, I was only scraping it with a knife though so chemicals might have worked better. I would love to teach Ben but as of now he doesn't have much interest in the stuff I do. I hope when he gets older he will get more interest. All the independent shops round here have closed a long time ago. There is a RS counter nearby so maybe they might be more knowledgeable about the different components :-)
I felt that when he says "Oh I don't believe it... There was nothing wrong with that" 😭😂🤣
Thanks a lot. It also worked for the IKEA DW60
Flyback diode... good work man 👌
Thank you :-)
Hi Vince, this is a LL4148 diode.
Thanks so much Amerya. I looked for ages online and I couldn't find out this info. The one I installed was a 1N4148 so it looks like I got lucky this time as I think it is the same but with through hole legs :-) Thanks again. Vince :-)
Great video, Vince! So happy you get it working! :-)
Most diodes can be replaced with other general diodes and work, but if the diode you use to replace a faulty one can not handle the voltage and current applied to it, it will eventually fail.
It should be noted diodes can fail but before they completely fail, they can exhibit strange "intermittent" behaviour especially when their environment has large temperature variations and or when the voltage is completely removed from them, allowing the discharge of the capacitance that they seem to develop, thus discharging the capacitance apparently resets them.
Having said that I would mark the date you replaced the diode and after three years if the heater hasn't failed I am pretty confident you may have actually turned a Factory Lemon or a refurbished Dish washer into a proper "Factory specified" functioning Dishwasher.. TIME WILL TELL...
As Usual I dropped you a Like Vince,
Cheers for the info Koala :-)
This kept me occupied for a while. Was a bit drastic removing the microprocessor for the sake of a s/c surface mount (SMD) LL1N4148 diode. I hope your Zanussi is still washing dishes ok?. It used to be the appliance of science in my day before I moved here to Aus.
great video to watch 🔧
For future reference: “Spule” is German for coil :)
Vince: that heater is faulty
1 hour of the video left
Me: it's not gona be just a heater is it?
（i don't even have a dishwasher）
Interesting trying to fix mate.
Thanks mate :-)
My whirlpool dishwasher wont start anymore. I replaced the main board still nothing. I guess I'll try replacing the control panel.. sweet video vince!
Good Vidéo! D8 is a "Flyback diode" (see wikipedia). it's classic to use a 1N4148 for relays.
Thanks :-)
Good job well done! Maybe bare in mind the fire brigade have still got the useful speed dial number 999 lol didn't like the scorching on the pipe may turn out to be the next fire hazard after the dryers and fridges
Hi vince I haven't finished the full vid yet but just so you know you can test those relays quickly with a 9v battery and also you can click the lid off them and clean the contacts
Thanks Reace M :-)
@@Mymatevince so if I understand correctly, the reason you couldn't test the relay in circuit was because of the faulty diode across the coil, so could yiu now in theory test the relay in circuit? I'm sure last time I tested one of those relays on a washer control board I just tested it in circuit. Thanks for the vid and good job on this one, its difficult when you have little information and I love how you piece the puzzle together and solve the problem with what you have in front of you.
@@reacey Hi, yes I think that is correct. I am pretty sure if I tested the relay in circuit now I would hear it click as the faulty diode has been swapped out. You have to make sure the polarity is correct though when using your battery or power supply which I didn't do in the video :-)
@@Mymatevince thanks alot
Hi we have the exact same problem with our ZDT41 dishwasher, it seems to work if you leave it switched off completely at the socket for a while it seems to work again, I suspect this might have been your issue!! Also I suspect thermostats in these get stuck open and the circuit board then thinks the water is at temp. hence only cold water. Also as a side note these dishwashers do not like running with the salt light on as yours is, if we keep ours topped up it works better.
the diode across the coil is a flyback, it stops high voltage from sapping the transistor or micro controller, the zener diode is to voltage regulator in the circuit, ie if it goes over 5volts then it puts the rest to ground ::
Thanks Rob :-)
Hey Vince OL on the multimeter actually means Open Loop. Just in case you wanted to know.
Thank you :-)
Well done Vince. A question for the crowd. Obviously the flyback relay diode was the issue but what about all those shorts around the MCU. Is that normal?
Thanks abeleski, I would also like to hear some thoughts about the shorts :-)
hi there. excellent video. if the thermostat on the heater is blown is it ok to connect a wire
I have taken the control panel on my dishwasher apart several times and re-flowed the solder to the main power relay. This has always restored normal service though I did buy a replacement relay last time in readiness for the next "fault". Anything more than this and I would personally just buy a new machine.
Interesting dépistage right down to the single faulty element. Nice
Thank you :-)
Good work
The diode is there to prevent back EMF. Like the spark you get from unplugging the kettle. Relays are notorious for back EMF
2 years late....not really sure 😂. The Diode test only should work in diode mode to drop a voltage 0.5v nominal for most standard diodes, that diode has a short as 3 ohms in both directions. For someone who appears an amateur electrics DIYer you have far more patience than me and I troubleshoot daily, good work 👏
Both diodes you took off are 1N4148. The zeners are the grey blobs. The label DZ1 is the label for the grey blob. Also, since your push buttons and LEDS still worked, your microcontroller can not be shorted. A 1N4148 is a signal diode. It should not have been used for absorbing the EMF of the relay (it's parallel on the coil of the relay). It's not made for that. It's a design mistake. If it breaks again replace it with a 1N4001. A 1N4148 is rated for 100mA. Your relay is not that small, the flyback current may exceed 100mA. A 1N4001 is rated 1A.
Another great video! Curious where you got the blue work mat?
I bet the wife and wallet are happy about all this!
Great job, bro 👍
To me the diode you soldered in is ok, no need to change anymore. It doesn't have to be a smd type diode.
As Christian Ivarsson and Jason J wrote already it is an ordinary protecting diode for the transistor or IC switching the relais.
What wonders me is the short you measured between Vss and Vdd of that Controller IC while it was removed from the board.
But mirically it is working.
By the way @29:52 the word SPULE is german and means coil. The relais has a 12Vdc relais coil.
I currently have a similar problem with a washing machine and wish I could fix it as you did.
Like you I do not have any schematics and my boards are multilayer smd boards.
Nice job. relays should always be tested out of circuit for the best possible, more accurate readings. enjoy all your videos. I think I'll subscribe.
This is a supressor diode. Its supress high voltage spikes generatet by the coil in the relay in case the microcontroller switches the relay off.
You can use your Replacement. It should work fine.
Thank you :-)
The diode is in parallel with the relay to protect the driver from the voltage created by the relay when it is turned off , when you turn the relay on you create an electromagnet and when you remove the voltage as the magnetic field collapses it induces a voltage in the coil you need to shunt this voltage to prevent damage to the circuit that drives the relay ( try googling diode in parallel with relay you will find a better more in depth explanation )
to feel this connect a relay to a battery (something around 5 to 12 volts) and place your fingers on the relay coil when you disconnect the battery and you will get a shock
love the simplified explanation, and the diode only goes one way to block the field when it tries to return to the circuit, after the relay turns off (normally off).
Excellent explanation. Thank you :-)
@@Mymatevince You`re welcome Mate
That some clever stuff done there, so was mini melf at fault on the motherboard as i call it- would you know F8 code, temperature timeout is ?
Good video, thanks. I am trying to check the continuity on the heating element but just can't see exactly where to connect the probes in the clip? Any tips?