I work as an electronics repair engineer for industrial automation electronic circuits. Generally I first check fuses, then check for shorts on input and output. If no shorts are visible, I power up and see what happens (or doesn't) Sometimes a good bang! Usually the common faults are fuses, electrolytic caps, and your silicon components i.e short from collector to emitter on IGBTs or shorts on MOSFETS. Logic IC's can also sometimes go bad, if you haven't got a logic tester, swap them out anyway. Sometimes it's as simple as the caps or a varistor gone boom from a surge, other times it takes you hours to figure out what the hell is wrong. But that's why I love electronics engineering, there's always a good puzzle to solve :D
Big Clive makes interesting videos that are far more entertaining and informative than anything on TV.........Keep up the good work Clive, because there are many of us who really enjoy your stuff !!
Markon was a company on its own. I worked on a lot of their product in the early 80s. All the machines I saw were 4 pole synchronous machines. The exciter machine rotor was on the same shaft as the main alternator rotating field. They were coupled together with a three phase full wave bridge rectifier. I never saw a Markon alternator with slip rings. They were all brushless. Markon was purchased by Cummins Generator Technologies. CGT id a body part of Cummins Inc. They combined Markon with another acquisition called Sawafuji. So if you search the combined name you will find them. My last job was with Cummins South Pacific doing exclusivel diesel generators from cute little toys up to 2 MVA. I played with an installation that had sixteen of those running as a diesel peaking power station. All up I had about thirty five years of diesel power generation. I have never seen one of those AVRs. The AVRs I saw in Markon alternators were not branded Markon. I think they were branded Contrology but I'm not sure. Love your work Clive thank you.
Lead-free rework... ugh. When in doubt, add more flux. Yes, more flux. More flux. Mooooooorrre fluuuuuuuuxxxxx. Finally get the shits and dump a load of Sn/Pb into it, then remove all the nasty alloy, then clean up the flux residue, then start again from scratch while hoping you haven't cooked anything important. So much fun!
And don't forget it's got to be the nasty flux, the stuff that doesn't burn off before you hit reflow temp (around 220c, requiring 350 on a hot air rework tool) AND you only get around 3 attempts before you've exceeded the components specifications, burnt the PCB, melted pads/track off or made a nice hole in your anti-static matting.
Clive, the conformal coating that used to be used for weatherproofing telephone equipment was a two-part urethane varnish. Unfortunately, i don't have precise specifications. As regards resistor failure, it's EXTREMELY common in equipment where capacitors have been secured with a petroleum-based contact adhesive (e.g. Evo-Stick). When this glue is heated, it gives off an acidic chemical, which corrodes metal - especially resistor connections. So look out for glue that's turned dark brown. It should be scraped away completely and the area cleaned with IsoPropanol.
Thank you so much for this, Clive. I've been struggling with this for ages. I'm talking about the return path (AC). This video doesn't intentionally cover it, but it filled the missing jigsaw piece for me. I phone my Dad a lot about it (he used to do similar stuff to the video you did about your training -he also did stuff fot the Navy and went on to Mainframe computers), but felt I sounded stupid asking questions that I didn't have the words for (there are no stupid questions; just stupid answers) Just saying, cheers, your videos help a lot.
I used to build gensets using Markon alternators. On the smaller ones they used a bypass system for the AVR where if the voltage went to high it shorted the field winding's which were usually the stator in those designs, the field current was supplied by an inductor. This was even the case on 15 KVA 3 phase units up until the mid 80's. I used Markon and Newage alternator units back then but Markon were my favourite for farmers and builders as they were so simple and robust Newage were better for industrial use due to better regulation.
just a point about measuring in circuit resistors (Which I'm sure you're aware of )..... If you measure across a resistor, the reading cannot be higher than the spec of the resistor because of external parallel routes. If the external circuits are of low values of ohms then they might mask the faulty resistor but if they are of a higher value then the faulty resistor may reveal itself. Love your vids by the way Clive
I used to rewind Markon Generators and do repairs. Im not sure if any were 1978 era but apart from the stator back end being burnt out the usual fault was the rotor diodes. Bolted into the rotor were two diodes connected (soldered) to the rotor windings and these were the first things you checked when one came in for repair then after the usual winding tests i basicly did what you did but before we threw the semiconductors we tested them.
I think I know what you mean, you can go out and buy a heatsink and a lot of the components that still look like that. I think that LED was probably old inventory in '78 cos the 3 & 5 mm plastic package were available by that time which looked like the ones you can still get now.
Well, my Sony TC-U2 tape deck uses an led for the record indicator and it was made in 1978 too. It was weak so I had to put another resistor in parallel with the original to increase the brightness :)
Reminds me very much of the early car alternator external regulator modules, (obviously being an AC generator) where the electromagnetic rotor (armature) was excited through electronically controlled DC. Initially the DC regulation output was compared to the battery voltage by a 12 Volt 3 Watt lamp (battery symbol on the dashboard) which would light without engine running. The current flowing through the lamp would pass through the regulation circuit to the alternator slip rings to the rotating electromagnetic rotor generating a magnetic field. Once the engine runs, the magnetic field induces current in the stator supplying current to the regulator circuit causing the output voltage to rise to charging voltage for the battery, the output voltage of the regulator and battery voltage would then be the same, extinguishing the battery lamp on the dash. The current to the electromagnetic rotor will now be regulated from the regulator by sensing the DC output voltage. Interesting to see this similar principle on this circuit board.
I know it was the first thing you checked Clive, it was just that you got right through the video and didn't tell us so, so I was waiting for the other shoe to drop, as it were. I managed to follow the slate elevator control, but I was struggling a little with this one. 8-)
That's what it would be, if I was messing about, but I'm erm... only just capable of not killing myself with it. I expect Clive has a qualification or two.
There are a couple of tricks to measure resistance in circuit. A low test voltage is the known solution for cases where the bypass path contains semiconductors. I have seen as low as 24 mV offered by a meter. For resistive paths you can use 4-terminal ohms measurement with the twist that the drive and sense leads are at different branches and then you swap them. For inductive bypass paths you can measure AC resistance at two or more frequencies. Another thing, the SCR may behave fine with the lamp load, but fail to stay ON after trigger with an inductive load without some help. The adjacent components might have been bad, but of course you replaced them in this case.
Ideally to set stability, you hook up an analog meter to your generator output, with the generator running, turn stab pot until it becomes unstable then go back the other way until it just becomes stable again.
That lower pot on the left is the Integral control adjustment of the AVR. From how Clive described it the unit functions as a P+I (Proportional + Integral) controller to regulate the voltage with an additional underspeed cutoff.
And that reminds me, we need to dig out that Stamford C20B of 1978 vintage, and see if it still works! Honestly and truly, we have one on the farm - We also have a 1978 Perkins 4-154 engine to drive it, if we ever get round to marrying the two together.
And Oxford Electrical Products STILL make the little PT4 pulse transformer - not bad! Reason I noticed - I built a thyristor trigger circuit using them a few weeks ago ;-)
Spent many a happy hour cleaning up brushgear and sliprings on the 600 MW alternator sets at Longannet Power Station. We also used to check the brush lengths 'on load' so I know all about one of the drawbacks, from a maintenance perspective, of dc generators and motors, i.e. carbon brushes. Another bugbear was maintaining the switchgear for our emergency standby motors (oil pumps etc.) with mechanical timers, argh! I dare say modern switchgear is much more efficient but we used to dread getting jobs on dc plant. Just a wee insight from an electrical fitters point of view!
Great Video Clive! These trouble shoot/repair videos are SO much more instructive than tear downs! Can you include more repair/mod/ reverse engineering videos? (p.s. you didn't say if you fixed the problem? . . update?)
directly uploading from ipad to youtube, using the app, maxes it to 720p, to do 1080p he have to use a pc to download the file from ipad and then upload
Not entirely comparable, but I have spent time fixing up several 1970's-era HP 141T spectrum analyzers, and I found that the resistors in those fail open-circuit quite often. The linear voltage supplies in the display mainframes run fairly warm and are the most common failure. When it isn't one of the transistors, it is usually a resistor. Thanks to the non-switching linear supplies, the old electrolytics have actually proven reasonably robust and rarely fail outright.
Clive, maybe you can help me with something. I recently took apart a big printer (like the cabinet style ones used in business). Apart from several (lots!) of really useful parts, inside was an LED strip with an odd configuration. It has parallel sets of 7 SMD LEDs in series with 2 resistors in between each. The resistors are so small I can't see their values. What's also odd is that it looks like each set of 7 LEDs is split with a resistor, so there are 4 LEDs, then a resistor, then 3 LEDs, all in series, followed by 2 resistors and another set of 7 LEDs + 1 resistor. I'll have to look at it closer to figure out whether the 2 resistors between each set are in series or parallel with the rest of the circuit. Could you explain why they used 2 resistors between each series set, and why there's a resistor in the middle of the 7 LEDs? If it would help I can take a picture and put it on imgur or something.
Great video, thankyou. I have a Plessey Aerospace 25Kva 3 phase generator which is running over voltage. It has gradually crept up and gone past the ability of the trimpot on the front of the AVR box and will no longer hold after excitation. There are 6 circuit boards in the AVR box and I think I might have a go at testing/ replacing some of the common components after watching your video. Although one of the boards has 5 trimmer potentiometers/ resistors and one of the screws appears to be much further out than the others. Problem is there are 2x 20k 1x 5k 1x 2k and 1x1k so don't think i can compare them? Unless the one 20k is at min or max value then it might be worth adjusting to see the effect?
Hey Clive, i really enjoy your video's! Ive got a question though, i fix up small (3-10kw) generators quite often and am wondering if you have a suggestion for any universal aftermarket avrs that would hopefully be more reliable than the original chinese crecent shaped ones.
Sir with due respect to your knowledge , i would like to ask you very basic question . to repair any modern / current model of avr , first thing you have to do is remove the epoxy layer or you can say epoxy coating applied on its pcb . please if possible let me know the method to do so because any kind of repair is possible only after removing off this epoxy resin . thanks.
what would be your preferred way to remove the soft potting material? ive got a AVR out of a Honda eb12d generator, they havent been made in 30 years so repair is my only option
Thanks for the great videos. The power supply voltage converter on my 2013 MacBookPro 15" won't allow the battery to charge once again...this is the 4th time in one year. They mentioned some carbon resulting in a burn again. The last time it was repaired, they mentioned that the charging circuit internal to the computer. That is to say the charging circuit between the adapter to the motherboard. Is there any way to fix this so it won't break again? Or a way to plug a different charging hook up internal to the computer. What would be the perfect fix would be to hook the laptop to a DeWalt tool battery (20V)...I'd need to get the components. I've cleaned the contacts which worked he first time and now won't fix or "band-aid" the computer. The computer is way out of warranty but the repairs are getting expensive. Seems like the component is the magnetic attachment of the charger to the computer gets really hot. thanks, Chuck
but unless you lift one side, the rest of the components mess you up, if you are lifting a leg of any cheap component, might as well just lift the other and replace it
You start with a thorough visual inspection first, then test the most likely, not the easiest. Testing each resistor could take hours. Besides, resistors aren't always the easiest to test. Without a schematic, you would need to desolder one side of each resistor. You risk damaging good components. To make it worse, the conformal coating can make testing difficult.
I have the same Markon MS1B AVR circuit in which I can adjust the voltage but not the Hz meter. It swings without able to adjust with the STAB pot. Could you give me an advice on this problem?
I thought most small generators in the KVA size are still typically 240v/415v what other generator voltages are used these days? Naturally the big MVA units run at medium voltages. Also its common for parts to fail due to corrosion and rust creeping in via the component leads..I've seen it a lot where the air in the environment can pass through via a vent in the enclosure and humidity and contaminants damage the PCB. I've seen DIL IC leads completely rusted away, even green mess where the copper tracks are eaten away. The con-formal coating is a must. The older stuff works and it's usually easier to fix, I find.
High, I have a 3 Phase 400V 11.5 KVA alternator with slip rings. Exciting field resistance is 8 Ohms. Can you help me to seize a proper AVR, what would be the current requirement?
Hi I have a Dunlite generator 3 kva and its gotta be about 15 to 20 years old judging by the factory yellow faded paint on every component. Problem is its putting out 335 volts at 49 -50 hertz and when I drop the rpm i can get between 240 to 250 volts but at around 10 -15 hertz! My question is should it have an avr as this looks ancient and btw there is a two screw terminal block with two brass or copper large flathead screws (i thought they were adjustable screws unless its for dc charging. I have worked with electronic boards,lawnmower repair,auto repair etc? Any reply appreciated as too why I have overvoltage problem? Great and informative vid and im about to strip it down to repair it ! Technical tips would be awesome? Thanks again from Australia 😊
I had a resistor fail in a Heathkit Scope while using it at work. It took out a ceramic capacitor and a VP. It stopped there. The shop was moving, I had asked about the scope, the scope was owned by the bosses friend, couldn't contact him, it became mine. Replaced the burned parts, it worked. It needs to be recapped. One day.
I need to build a much simpler one..basically 15v dc to the rotor is good enough. The exciter winding produces 7vac, but once it is up to power, it produces 150vac, so makes it complicated. I am trying just a simple bridge with 15v zener, what will go wrong?
DO YOU KNOW ANY THINK ABOUT CARS THE BODY CONTROL MODULE IT WORKS THE LIGHTS WINDOWS ANTI THEFT SYSTEM ABS I HAVE 64 CHEVY NOVA I BOUGHT 2014 CAMARO AND PUT IT ALL IN THE NOVA DASH, MOTOR, TRANS, THE MODULE WORK ON A CAN SYSTEM I HEARD YOU CAN BY PASS LIKE THE ABS AT THE SOURCE ANY HELP WOULD HELP ME LOTS THANKS TOMMY
question from a newbie: do i understand correctly that to regulate the voltage at 10v with the zener diode, the anode of the zener is connected to ground, and the rest of the circuit is power by this reference voltage, being connected in parallel with the zener? am i correct? something i missed?
I wonder what might happen if you apply three phases to a standard motor that inky uses two (well, one) phase, would it try and pull more to one side, 1,2+3 or 1+2,3 or 1+3,2... Would it not work, or be slow to start, or fast to reach top speed... Weirdness
Some manufactures pot their electronics for protection, but it doesn't work the well, the potting resin prolongs the life but it does break down and moisture forces its way in through the fine cracks, especially if the units gets warm to hot, as it heats then cools it sucks in the moisture. The real reason for potting is so you cannot fix it and force you to buy a new one.
Not related to the video. If we were to create the power grid from scratch - for example on mars, what should the frequency be - do you think rising frequency would be better for easier transformation? Or would that cause problems with the skin effect?
Does the gain in distribution efficiency offset the negatives of designing a more complicated grid? Actually, before i ask that, which of the two variants (AC&DC) require the most complexity to fill a modern nations power distribution needs? Which challenges arise from a DC power grid versus an AC one? Except for now having to replace every transformer ever with a buck converter, of course...
You know, older R/C cars use a wax to seal the board, it works real well. I've had a 70's R/C airplane control board and the parts were like new, environmentally speaking (the board was fried, from too much juice I think).
You could use a polyurethane varnish on the board, it's what i use for high voltage stuff (actually floor varnish), and maybe a couple of blobs of hotglue on the ends of the chips to stop them falling out with vibration I used to work with generators as part of my job
I know, but as clive said, the guy might only want it running for a few more years due to age of the machine, no point is spending a lot of money on conformal coating or potting, plus potting would make it hard to repair it again, specially as clive has made it easy to change the chips ;)
Miller Stevenson makes a spray on conformal coating. I got some and sprayed it on the alloy wheels on my car. Looked pretty cool in the sunlight because it has a UV fluorescent dye so you know your board got coated.
I use a generic spray-on conformal coating (available from local electronics retailer or fleabay) for ELV pcb's, it's "solder-through" so it makes rework/repair easy. But it's a pretty light lacquer, not sure how appropriate it would be for high voltage applications.
It was mentioned that resistors rarely fail. Actually I frequently find failed resistors, particularly carbon, and older type carbon film. Typically they go very high value or O/C. Older type high stab and metal oxide type seem very reliable.
I haavrve an stamford mx321, the generator output voltage is not stable the output line voltage ranges from 381to 410 volts l changed the stability trimmer and the volt trimmer in the avr and the problem remains,when I connected a new avr it works properly ,is there any repairs could be done to the old avr ???
I have a generator with the same AVR fitted. It failed when the generator went to an over voltage and then blew the fuse on the AVR board. I replaced the fuse and after 20 seconds it blew again. Once the fuse was blown the generator produced no power. Could this be a similar fault and if not, any ideas?
I guess this is from a large-ish generator, not one of the portable ones you can put in the back of a car or van. I say this because many portable generators use a brushless alternator which just has a separate winding connected to a capacitor for excitation and no AVR. They also usually have a diode in series with the rotor winding with a VDR across it. The regulation may not be as good as with AVR alternators but for reliability and cost of maintenance and repair they are the simplest and the best.
Makes me glad that my Honda EX650 generator is a very simplistic setup (though replacing the diodes & resistors on the rotor was a right PITA!!), if I had to fix an AVR then I'd have probably given up on it!! :S
bigclivedotcom Very true, just wish it was that simple with my EX650, getting its diodes off the rotor was just a PITA, almost ruining it in the process, but it works now, and that's what matters... :)
given everything else you renewed, wouldn't it have been sensible to replace the MOVS? They are gradually degraded in use and could be getting ineffective.
This is interesting... Not how you think.. I've a little project, and I predate electronics, so seeing this "evolution" is interesting and entirely reminds me of "complex electronics" granted some have become simple but the analogue or mechanical was and is far more simple and robust. I was simply looking for the voltage regulators and if they still live in old formats as it's been a few decades since I have seen or had one. I think the last ones, were a automobile we tend to know as the Morris minor, era as they later phased out in the production. Obviously they were not used in automobile, but in power generation on a massive scale. I think they were a inductive switch/really with two poles that regulates power. Much more simple.
you need to test it with a variac. As you go from 0 to say 200 (assuming the avr is a 230V type) the lamp should get brighter with the mains in. As you approach 230V the lamp will stop getting brighter and start getting dimmer as it thinks the correct voltage has been reached and it must reduce the field to maintain it balanced. The output will be smoothed by the inductance of the field coils. Since it's a closed loop system, the output will always appear 'all or nothing' on the bench because it's trying to balance within tight tolerances.
I cringe when anyone runs a metal screwdriver around a live PC board. I have seen many let the magic smoke out with the wrong move, even worse when one deals with a fire emitting transistors. Nice to see good old fashion technology that keeps on ticking and is easy to work on.
Looks like Markon Engineering provided the MS1/B to Power Drive Systems where they labeled it the AVR6e. Here's some documentation that contains technical specs, steps for adjusting settings, information on how to test it as well as some very crude diagrams. www.powersystems.com.au/tech_pdfs/avr6e_manual.pdf
I have a Dunlite generator with one unit output of 50 hz frequency at 300 volts. And another Dunlite generator with 50 to 90 hz at 4 volts even though I plugged a fan ito it? Any reply appreciated thanks?
When I repair industrial control PCBs, it's "standard operating procedure" to thoroughly inspect the board visually (after a good cleaning). Saves a tremendous amount of time and money.
Conformal coating: otherwise known as clear fingernail polish, or spray Krylon (at least in the US). The fingernail polish has the advantage that you can brush it onto the ends of the components and not get it all over the place.
Hello Friend I have a problem on my AVR MS1 / B card, burned the ZD1 and I do not have the reference, Could you help me and tell what the reference? thanks, greetings
Aye markon still on the go I still use the 5kva in some machines miby they have been bought over but still can get hawd of there genny ends never seen one wae a AVR in ages tho
I work as an electronics repair engineer for industrial automation electronic circuits. Generally I first check fuses, then check for shorts on input and output. If no shorts are visible, I power up and see what happens (or doesn't) Sometimes a good bang! Usually the common faults are fuses, electrolytic caps, and your silicon components i.e short from collector to emitter on IGBTs or shorts on MOSFETS. Logic IC's can also sometimes go bad, if you haven't got a logic tester, swap them out anyway. Sometimes it's as simple as the caps or a varistor gone boom from a surge, other times it takes you hours to figure out what the hell is wrong. But that's why I love electronics engineering, there's always a good puzzle to solve :D
Big Clive makes interesting videos that are far more entertaining and informative than anything on TV.........Keep up the good work Clive, because there are many of us who really enjoy your stuff !!
I love those old and well designed circuits, thanks for showing it
Markon was a company on its own. I worked on a lot of their product in the early 80s. All the machines I saw were 4 pole synchronous machines. The exciter machine rotor was on the same shaft as the main alternator rotating field. They were coupled together with a three phase full wave bridge rectifier. I never saw a Markon alternator with slip rings. They were all brushless. Markon was purchased by Cummins Generator Technologies. CGT id a body part of Cummins Inc. They combined Markon with another acquisition called Sawafuji. So if you search the combined name you will find them. My last job was with Cummins South Pacific doing exclusivel diesel generators from cute little toys up to 2 MVA. I played with an installation that had sixteen of those running as a diesel peaking power station.
All up I had about thirty five years of diesel power generation. I have never seen one of those AVRs. The AVRs I saw in Markon alternators were not branded Markon. I think they were branded Contrology but I'm not sure.
Love your work Clive thank you.
I'm just a hobbyist, but I learn so much from this channel
Pre-RoHS, not surprised it lasted as long as it did!
The solder melted, reflowed and removed beautifully compared to the crusty lead free stuff we're saddled with now.
Lead-free rework... ugh. When in doubt, add more flux. Yes, more flux. More flux. Mooooooorrre fluuuuuuuuxxxxx.
Finally get the shits and dump a load of Sn/Pb into it, then remove all the nasty alloy, then clean up the flux residue, then start again from scratch while hoping you haven't cooked anything important. So much fun!
And don't forget it's got to be the nasty flux, the stuff that doesn't burn off before you hit reflow temp (around 220c, requiring 350 on a hot air rework tool) AND you only get around 3 attempts before you've exceeded the components specifications, burnt the PCB, melted pads/track off or made a nice hole in your anti-static matting.
These troubleshooting/fixing videos are awesome ! Loving this stuff
A sharp contrast to a modern generator's AVR that's completely potted in epoxy how things have changed.
I wanted to get some of the cheap Chinese units to make a video about, but they are all potted in black resin, which is a shame.
Can you repair an AvE?
I know of one that has some very unusual output distortion.
Clive, the conformal coating that used to be used for weatherproofing telephone equipment was a two-part urethane varnish. Unfortunately, i don't have precise specifications.
As regards resistor failure, it's EXTREMELY common in equipment where capacitors have been secured with a petroleum-based contact adhesive (e.g. Evo-Stick). When this glue is heated, it gives off an acidic chemical, which corrodes metal - especially resistor connections. So look out for glue that's turned dark brown. It should be scraped away completely and the area cleaned with IsoPropanol.
Well done for talking about AVRs for so long and not mentioning "droop" :-) Great video, I wonder if it is still working nearly 6 years later...
This video made me very happy. I don't know why, I just like it.
Thank you so much for this, Clive. I've been struggling with this for ages. I'm talking about the return path (AC). This video doesn't intentionally cover it, but it filled the missing jigsaw piece for me. I phone my Dad a lot about it (he used to do similar stuff to the video you did about your training -he also did stuff fot the Navy and went on to Mainframe computers), but felt I sounded stupid asking questions that I didn't have the words for (there are no stupid questions; just stupid answers)
Just saying, cheers, your videos help a lot.
The only stupid question is the one that wasn't asked ;)
No, there are definitely stupid questions.
Nice explanation of how that circuit works. Very helpful for those that want to learn how to understand circuits. Thanks
I used to build gensets using Markon alternators. On the smaller ones they used a bypass system for the AVR where if the voltage went to high it shorted the field winding's which were usually the stator in those designs, the field current was supplied by an inductor. This was even the case on 15 KVA 3 phase units up until the mid 80's. I used Markon and Newage alternator units back then but Markon were my favourite for farmers and builders as they were so simple and robust Newage were better for industrial use due to better regulation.
This guy should get at least 500.000 subscribers...
Wow! You were awesome even back in the Vaudeville days! 😂 Yes, I am the Ancient One. Love You, Clive.
just a point about measuring in circuit resistors (Which I'm sure you're aware of )..... If you measure across a resistor, the reading cannot be higher than the spec of the resistor because of external parallel routes. If the external circuits are of low values of ohms then they might mask the faulty resistor but if they are of a higher value then the faulty resistor may reveal itself.
Love your vids by the way Clive
I used to rewind Markon Generators and do repairs. Im not sure if any were 1978 era but apart from the stator back end being burnt out the usual fault was the rotor diodes. Bolted into the rotor were two diodes connected (soldered) to the rotor windings and these were the first things you checked when one came in for repair then after the usual winding tests i basicly did what you did but before we threw the semiconductors we tested them.
That's a brushless design with the field rectification diodes on the rotor
That actually looks almost modern for the time... in a way.
I thought that too
To me it looks home made, at least compared to the ones my dad used to make.
1978 with an LED! Quite impressive.
I think I know what you mean, you can go out and buy a heatsink and a lot of the components that still look like that. I think that LED was probably old inventory in '78 cos the 3 & 5 mm plastic package were available by that time which looked like the ones you can still get now.
Well, my Sony TC-U2 tape deck uses an led for the record indicator and it was made in 1978 too. It was weak so I had to put another resistor in parallel with the original to increase the brightness :)
Reminds me very much of the early car alternator external regulator modules, (obviously being an AC generator) where the electromagnetic rotor (armature) was excited through electronically controlled DC. Initially the DC regulation output was compared to the battery voltage by a 12 Volt 3 Watt lamp (battery symbol on the dashboard) which would light without engine running. The current flowing through the lamp would pass through the regulation circuit to the alternator slip rings to the rotating electromagnetic rotor generating a magnetic field. Once the engine runs, the magnetic field induces current in the stator supplying current to the regulator circuit causing the output voltage to rise to charging voltage for the battery, the output voltage of the regulator and battery voltage would then be the same, extinguishing the battery lamp on the dash. The current to the electromagnetic rotor will now be regulated from the regulator by sensing the DC output voltage. Interesting to see this similar principle on this circuit board.
Anyone else waiting for Clive to tell us it was the 5 Amp fuse ?
That was the first thing checked.
I know it was the first thing you checked Clive, it was just that you got right through the video and didn't tell us so, so I was waiting for the other shoe to drop, as it were.
I managed to follow the slate elevator control, but I was struggling a little with this one. 8-)
That's what it would be, if I was messing about, but I'm erm... only just capable of not killing myself with it. I expect Clive has a qualification or two.
No, I was expecting the LED to be changed to a warm white one.
Tommy Oz n
There are a couple of tricks to measure resistance in circuit. A low test voltage is the known solution for cases where the bypass path contains semiconductors. I have seen as low as 24 mV offered by a meter. For resistive paths you can use 4-terminal ohms measurement with the twist that the drive and sense leads are at different branches and then you swap them. For inductive bypass paths you can measure AC resistance at two or more frequencies. Another thing, the SCR may behave fine with the lamp load, but fail to stay ON after trigger with an inductive load without some help. The adjacent components might have been bad, but of course you replaced them in this case.
Ideally to set stability, you hook up an analog meter to your generator output, with the generator running, turn stab pot until it becomes unstable then go back the other way until it just becomes stable again.
That lower pot on the left is the Integral control adjustment of the AVR. From how Clive described it the unit functions as a P+I (Proportional + Integral) controller to regulate the voltage with an additional underspeed cutoff.
And that reminds me, we need to dig out that Stamford C20B of 1978 vintage, and see if it still works! Honestly and truly, we have one on the farm - We also have a 1978 Perkins 4-154 engine to drive it, if we ever get round to marrying the two together.
And Oxford Electrical Products STILL make the little PT4 pulse transformer - not bad! Reason I noticed - I built a thyristor trigger circuit using them a few weeks ago ;-)
I love your videos they are so relaxing to watch and learn lot. Keep up the your good work thank you
Fantastic Video Clive. It was so informative & helpful. Keep up the great work. Nick.
Spent many a happy hour cleaning up brushgear and sliprings on the 600 MW alternator sets at Longannet Power Station. We also used to check the brush lengths 'on load' so I know all about one of the drawbacks, from a maintenance perspective, of dc generators and motors, i.e. carbon brushes. Another bugbear was maintaining the switchgear for our emergency standby motors (oil pumps etc.) with mechanical timers, argh! I dare say modern switchgear is much more efficient but we used to dread getting jobs on dc plant. Just a wee insight from an electrical fitters point of view!
Great video as always, Clive. The fact you're not verified yet is criminal to be honest.
Great Video Clive!
These trouble shoot/repair videos are SO much more instructive than tear downs!
Can you include more repair/mod/ reverse engineering videos?
(p.s. you didn't say if you fixed the problem? . . update?)
Yes, the AVR was fixed. The faulty component was a resistor that had changed value dramatically.
thank you it helped me for my exams
a schematic could be handy - its all off the shelf style, could be handy for diy gensets
@bigclivedotcom may i ask why your videos are in 720p not 1080p?
directly uploading from ipad to youtube, using the app, maxes it to 720p, to do 1080p he have to use a pc to download the file from ipad and then upload
720p is the maximum resolution of the iPad2. On a slow data connection it still takes a very long time to upload 720p.
I know how you feel about the slow data connection my upload speed just above 1mbps
my upload speed is below 0.5mbps :(
Not entirely comparable, but I have spent time fixing up several 1970's-era HP 141T spectrum analyzers, and I found that the resistors in those fail open-circuit quite often. The linear voltage supplies in the display mainframes run fairly warm and are the most common failure. When it isn't one of the transistors, it is usually a resistor. Thanks to the non-switching linear supplies, the old electrolytics have actually proven reasonably robust and rarely fail outright.
Clive, maybe you can help me with something. I recently took apart a big printer (like the cabinet style ones used in business). Apart from several (lots!) of really useful parts, inside was an LED strip with an odd configuration. It has parallel sets of 7 SMD LEDs in series with 2 resistors in between each. The resistors are so small I can't see their values. What's also odd is that it looks like each set of 7 LEDs is split with a resistor, so there are 4 LEDs, then a resistor, then 3 LEDs, all in series, followed by 2 resistors and another set of 7 LEDs + 1 resistor. I'll have to look at it closer to figure out whether the 2 resistors between each set are in series or parallel with the rest of the circuit. Could you explain why they used 2 resistors between each series set, and why there's a resistor in the middle of the 7 LEDs? If it would help I can take a picture and put it on imgur or something.
Maybe it's too late for me but a picture might help here if possible.
I'll snap a picture the next time I'm down in the shop (probably later tonight).
7 months later...
You said that 7 months ago... it is time.
Did you keep your old place in Glasgow when you moved or has that gone now
Great video, thankyou. I have a Plessey Aerospace 25Kva 3 phase generator which is running over voltage. It has gradually crept up and gone past the ability of the trimpot on the front of the AVR box and will no longer hold after excitation. There are 6 circuit boards in the AVR box and I think I might have a go at testing/ replacing some of the common components after watching your video. Although one of the boards has 5 trimmer potentiometers/ resistors and one of the screws appears to be much further out than the others. Problem is there are 2x 20k 1x 5k 1x 2k and 1x1k so don't think i can compare them? Unless the one 20k is at min or max value then it might be worth adjusting to see the effect?
Brought back memories of fault finding on Lucas (Prince of Darkness.) ACR alternators, which were controlled in a similar way. They were really crap.
Hey Clive, i really enjoy your video's! Ive got a question though, i fix up small (3-10kw) generators quite often and am wondering if you have a suggestion for any universal aftermarket avrs that would hopefully be more reliable than the original chinese crecent shaped ones.
I couldn't recommend any specific one, but it might be worth buying a few different types and experimenting with them.
Very nice lecture and highly interesting subject matter. Thanks a lot!
Sir with due respect to your knowledge , i would like to ask you very basic question .
to repair any modern / current model of avr , first thing you have to do is remove the epoxy layer or you can say epoxy coating applied on its pcb . please if possible let me know the method to do so because any kind of repair is possible only after removing off this epoxy resin . thanks.
what would be your preferred way to remove the soft potting material? ive got a AVR out of a Honda eb12d generator, they havent been made in 30 years so repair is my only option
If it's the rubbery material then it can be picked out carefully. If it's resin it's harder and requires a bit of heat.
It would be great to get a teardown of a modern honda/clone AVR with feedback winding/trim pot etc.
Thanks for the great videos. The power supply voltage converter on my 2013 MacBookPro 15" won't allow the battery to charge once again...this is the 4th time in one year. They mentioned some carbon resulting in a burn again. The last time it was repaired, they mentioned that the charging circuit internal to the computer. That is to say the charging circuit between the adapter to the motherboard. Is there any way to fix this so it won't break again? Or a way to plug a different charging hook up internal to the computer. What would be the perfect fix would be to hook the laptop to a DeWalt tool battery (20V)...I'd need to get the components. I've cleaned the contacts which worked he first time and now won't fix or "band-aid" the computer.
The computer is way out of warranty but the repairs are getting expensive. Seems like the component is the magnetic attachment of the charger to the computer gets really hot.
thanks,
Chuck
I'm amazed you didn't throw a multimeter over the simple components first. Always start with the easiest things first.
but unless you lift one side, the rest of the components mess you up, if you are lifting a leg of any cheap component, might as well just lift the other and replace it
You start with a thorough visual inspection first, then test the most likely, not the easiest. Testing each resistor could take hours. Besides, resistors aren't always the easiest to test. Without a schematic, you would need to desolder one side of each resistor. You risk damaging good components. To make it worse, the conformal coating can make testing difficult.
So do you repair this stuff for free for the purpose of youtube channel or do you charge?
I have the same Markon MS1B AVR circuit in which I can adjust the voltage but not the Hz meter. It swings without able to adjust with the STAB pot. Could you give me an advice on this problem?
Looking forward to a generator set up and load test video :-)
I was taught to solder the legs of components AFTER they have been cut, to seal the bare copper and discourage corrosion going up inside.
I thought most small generators in the KVA size are still typically 240v/415v what other generator voltages are used these days? Naturally the big MVA units run at medium voltages. Also its common for parts to fail due to corrosion and rust creeping in via the component leads..I've seen it a lot where the air in the environment can pass through via a vent in the enclosure and humidity and contaminants damage the PCB. I've seen DIL IC leads completely rusted away, even green mess where the copper tracks are eaten away. The con-formal coating is a must. The older stuff works and it's usually easier to fix, I find.
bjtaudio Gensets these days are often at the harmonized 230V/400V voltage rather than the old British 240V/415V or the old continental 220V/380V.
Smashing you repaired it clive ;-D, perhaps nail varnish or car laquer spray would do for the bare components perhaps :-)
Woooaahhh i live like 5 mins away from oakham where this is made that is awsome
Horay!! Thanks Clive for weekly "Kboom" video..
Cheers
Is this switch mode based? Because if not, why not just use a normal high tension voltage regulator?
I always thought these cute LEDs have plastic base. I still have two of them unused, just checked and the base is indeed ceramic.
Good video. I have learned alot from it. Keep it up
I like this...probably 30+ years old...!
I like using a isolating Transformer not just isolate the work but to limit the fault current as well.
They do reduce bang volume.
High, I have a 3 Phase 400V 11.5 KVA alternator with slip rings. Exciting field resistance is 8 Ohms. Can you help me to seize a proper AVR, what would be the current requirement?
Hi I have a Dunlite generator 3 kva and its gotta be about 15 to 20 years old judging by the factory yellow faded paint on every component. Problem is its putting out 335 volts at 49 -50 hertz and when I drop the rpm i can get between 240 to 250 volts but at around 10 -15 hertz! My question is should it have an avr as this looks ancient and btw there is a two screw terminal block with two brass or copper large flathead screws (i thought they were adjustable screws unless its for dc charging. I have worked with electronic boards,lawnmower repair,auto repair etc? Any reply appreciated as too why I have overvoltage problem? Great and informative vid and im about to strip it down to repair it ! Technical tips would be awesome? Thanks again from Australia 😊
Most generators should have some voltage regulating system. I'm not sure which system that one uses. Does the voltage stay high under load?
@@bigclivedotcom i plug a 600 w drill and a multimeter in the other socket and wont come down! Weird!
This type of regulator is quite common in generators until the 1980s here in Brazil ... here the voltage between phase to phase is 220v 60hz
I had a resistor fail in a Heathkit Scope while using it at work. It took out a ceramic capacitor and a VP. It stopped there. The shop was moving, I had asked about the scope,
the scope was owned by the bosses friend, couldn't contact him, it became mine. Replaced the burned parts, it worked. It needs to be recapped. One day.
I need to build a much simpler one..basically 15v dc to the rotor is good enough. The exciter winding produces 7vac, but once it is up to power, it produces 150vac, so makes it complicated. I am trying just a simple bridge with 15v zener, what will go wrong?
The second trimpot you described, were you looking for the word 'damping'? :-)
DO YOU KNOW ANY THINK ABOUT CARS THE BODY CONTROL MODULE IT WORKS THE LIGHTS WINDOWS ANTI THEFT SYSTEM ABS I HAVE 64 CHEVY NOVA I BOUGHT 2014 CAMARO AND PUT IT ALL IN THE NOVA DASH, MOTOR, TRANS, THE MODULE WORK ON A CAN SYSTEM I HEARD YOU CAN BY PASS LIKE THE ABS AT THE SOURCE ANY HELP WOULD HELP ME LOTS THANKS TOMMY
question from a newbie: do i understand correctly that to regulate the voltage at 10v with the zener diode, the anode of the zener is connected to ground, and the rest of the circuit is power by this reference voltage, being connected in parallel with the zener? am i correct? something i missed?
I wonder what might happen if you apply three phases to a standard motor that inky uses two (well, one) phase, would it try and pull more to one side, 1,2+3 or 1+2,3 or 1+3,2... Would it not work, or be slow to start, or fast to reach top speed... Weirdness
Some manufactures pot their electronics for protection, but it doesn't work the well, the potting resin prolongs the life but it does break down and moisture forces its way in through the fine cracks, especially if the units gets warm to hot, as it heats then cools it sucks in the moisture. The real reason for potting is so you cannot fix it and force you to buy a new one.
Clive, I am going to build this Markon AVR and I do not know the pulse transformer winding details, Could you help me to find it?
It's a wonder the stator windings haven't mechanically broken at that age. The vibration eventually work hardens them till they break.
I imagine if you put some lacquer or something on the IC's it would help to hold them in and to keep moisture out of the sockets.
Not related to the video. If we were to create the power grid from scratch - for example on mars, what should the frequency be - do you think rising frequency would be better for easier transformation? Or would that cause problems with the skin effect?
I think these days if we could start from scratch distribution might actually be DC.
How come? Could you elaborate on that?
Much lower losses over long runs, and most modern appliances could potentially run on DC.
Does the gain in distribution efficiency offset the negatives of designing a more complicated grid? Actually, before i ask that, which of the two variants (AC&DC) require the most complexity to fill a modern nations power distribution needs?
Which challenges arise from a DC power grid versus an AC one? Except for now having to replace every transformer ever with a buck converter, of course...
You should really do a video where you discuss the (dis)advantages of both AC & DC grids as you imagine them!
You know, older R/C cars use a wax to seal the board, it works real well. I've had a 70's R/C airplane control board and the parts were like new, environmentally speaking (the board was fried, from too much juice I think).
You could use a polyurethane varnish on the board, it's what i use for high voltage stuff (actually floor varnish), and maybe a couple of blobs of hotglue on the ends of the chips to stop them falling out with vibration
I used to work with generators as part of my job
Sparky Projects the newer ones are potted in a silicone rubber type compound
I know, but as clive said, the guy might only want it running for a few more years due to age of the machine, no point is spending a lot of money on conformal coating or potting, plus potting would make it hard to repair it again, specially as clive has made it easy to change the chips ;)
Miller Stevenson makes a spray on conformal coating. I got some and sprayed it on the alloy wheels on my car. Looked pretty cool in the sunlight because it has a UV fluorescent dye so you know your board got coated.
I use a generic spray-on conformal coating (available from local electronics retailer or fleabay) for ELV pcb's, it's "solder-through" so it makes rework/repair easy. But it's a pretty light lacquer, not sure how appropriate it would be for high voltage applications.
It was mentioned that resistors rarely fail. Actually I frequently find failed resistors, particularly carbon, and older type carbon film. Typically they go very high value or O/C. Older type high stab and metal oxide type seem very reliable.
I haavrve an stamford mx321, the generator output voltage is not stable the output line voltage ranges from 381to 410 volts l changed the stability trimmer and the volt trimmer in the avr and the problem remains,when I connected a new avr it works properly ,is there any repairs could be done to the old avr ???
I have a generator with the same AVR fitted. It failed when the generator went to an over voltage and then blew the fuse on the AVR board. I replaced the fuse and after 20 seconds it blew again. Once the fuse was blown the generator produced no power. Could this be a similar fault and if not, any ideas?
I guess this is from a large-ish generator, not one of the portable ones you can put in the back of a car or van. I say this because many portable generators use a brushless alternator which just has a separate winding connected to a capacitor for excitation and no AVR. They also usually have a diode in series with the rotor winding with a VDR across it. The regulation may not be as good as with AVR alternators but for reliability and cost of maintenance and repair they are the simplest and the best.
Makes me glad that my Honda EX650 generator is a very simplistic setup (though replacing the diodes & resistors on the rotor was a right PITA!!), if I had to fix an AVR then I'd have probably given up on it!! :S
These days you can get a wide range of AVRs online, so there's still hope if one fries.
bigclivedotcom
Very true, just wish it was that simple with my EX650, getting its diodes off the rotor was just a PITA, almost ruining it in the process, but it works now, and that's what matters... :)
Yeah, I have about 3 or so of those little ceramic-base red LEDs, plus some like it that are IR emitters.
given everything else you renewed, wouldn't it have been sensible to replace the MOVS? They are gradually degraded in use and could be getting ineffective.
They were replaced.
So does this predate the widespread use of DIACs as driving components for TRIACs?
The diac is normally used as a simple threshold device for dimmers, but in this case a chip with a decisive switching edge is being used.
This is interesting... Not how you think..
I've a little project, and I predate electronics, so seeing this "evolution" is interesting and entirely reminds me of "complex electronics" granted some have become simple but the analogue or mechanical was and is far more simple and robust.
I was simply looking for the voltage regulators and if they still live in old formats as it's been a few decades since I have seen or had one.
I think the last ones, were a automobile we tend to know as the Morris minor, era as they later phased out in the production. Obviously they were not used in automobile, but in power generation on a massive scale. I think they were a inductive switch/really with two poles that regulates power.
Much more simple.
you do great videos Clive!
you need to test it with a variac. As you go from 0 to say 200 (assuming the avr is a 230V type) the lamp should get brighter with the mains in. As you approach 230V the lamp will stop getting brighter and start getting dimmer as it thinks the correct voltage has been reached and it must reduce the field to maintain it balanced. The output will be smoothed by the inductance of the field coils. Since it's a closed loop system, the output will always appear 'all or nothing' on the bench because it's trying to balance within tight tolerances.
We do have a variac to test it with at the workshop. I'll give it a go when I return it.
Send me a message or email me meggerbiddle. To discuss the effects of electricity on the body.
I cringe when anyone runs a metal screwdriver around a live PC board. I have seen many let the magic smoke out with the wrong move, even worse when one deals with a fire emitting transistors. Nice to see good old fashion technology that keeps on ticking and is easy to work on.
Repair: just replace all the components, and you're done!
Looks like Markon Engineering provided the MS1/B to Power Drive Systems where they labeled it the AVR6e. Here's some documentation that contains technical specs, steps for adjusting settings, information on how to test it as well as some very crude diagrams.
www.powersystems.com.au/tech_pdfs/avr6e_manual.pdf
Imagine repairing a modern one and everything is SMT now
They are usually potted too, but Chinese copies are delightfully cheap if ordered directly, and in my experience, not too shabbily made.
I have a Dunlite generator with one unit output of 50 hz frequency at 300 volts. And another Dunlite generator with 50 to 90 hz at 4 volts even though I plugged a fan ito it? Any reply appreciated thanks?
Ah, yes, Visual inspection FIRST. That old chestnut. ;)
SigEpBlue
?
When I repair industrial control PCBs, it's "standard operating procedure" to thoroughly inspect the board visually (after a good cleaning). Saves a tremendous amount of time and money.
It's a shame that boards like this don't have a log book so you can see the history of repairs made by different engineers over the years.
What was the type number of the original schmitt chip? If 4049UB or 4069 they are still freely available, the 4049 less common, though..
mc14584bcp
Pin compatible with a 4069 but the 4069 is mostly available as unbuffered output 4069UB, the 4584 is buffered..
How do i get ahold of you if i have a bunch of generator boards that need repaired lol
please bro whats the similar chips that i can put to replace that motorola MC 14584BCP FZR 9621 ?
CD40106 ? CD40106BE ? 40106 DIP-14 ?
Conformal coating: otherwise known as clear fingernail polish, or spray Krylon (at least in the US). The fingernail polish has the advantage that you can brush it onto the ends of the components and not get it all over the place.
Hello Friend
I have a problem on my AVR MS1 / B card, burned the ZD1 and I do not have the reference, Could you help me and tell what the reference? thanks, greetings
Aye markon still on the go I still use the 5kva in some machines miby they have been bought over but still can get hawd of there genny ends never seen one wae a AVR in ages tho