Excellent stuff and great, practical genius fix. With all the logical, necessary, cautious steps to get there. Spot on. First class. This EE thanks you.
Thanks for video. This inspired me to immediately fix up my FY3200. My solution was just to cut the end off of a computer power cord. Remove the old socket from the FY3200. Thread the cord thru the rectangular hole. Make up some "creative" strain relief (involves hot glue!), and solder the wires. I used one of the ground lugs on back BNC connectors as a common point to collect up some ground connections.
At 15:35 you can see a surface mount resistor between the ground trace and a neighboring pad on the right hand side, makes me wonder if that is the cause of the leakage.
Thanks, glad it is helpful. Yes I am putting the switch together and recording the process. just takes time. Will be in a future video. Thanks for watching.
Good, easy repair, thanks for posting. As your switch is out of site on the back panel, I would advise adding an LED on the front panel showing when your device is in Float or Grounded mode (I tend to forget such things when they're out of site). Also, I have a competing product called an Instek MHS-5200A that's almost identical in appearance but confines its switching mode PS to a 5V, 200ma wall-wart. It therefore doesn't have the AC ground issues your unit has, but hash and ripple are no doubt still there. For that I plan to add a battery and LDO regulator to eliminate all switching problems entirely.
Thanks for sharing that information. I was thinking after reading this to just change the channel LEDS to dual green/red. So when in ground mode they would be green and when floating turn red. Should be an easy mod. Thanks for sharing.
Hey Buddy, great video, you have made the device safe for use and service. I do think it would be much better as you said to make a good linear supply or even one off the shelf that fits well. Thank you my friend. Rock on.... Joel
another option could be to place a single +12VDC socket on the back panel and get +5VDC from that with a cheap dc to dc converter in this way the main power supply will be completely external and could be a good linear one
Hello again Buddy ! ... I am still on catch up with all your vids so I am late posting sorry. I also have that Rigol scope and I am pretty confident that it would have been OK as the BNC's ground is actually earthed. Can't blame you for not trying it as doubt always plays tricks with your mind. Have a nice day and keep up the good work.
I was not aware that safety caps will short. I thought they were designed to open. Live and learn. BTW...I have this unit and will be making the change. Thanks, my friend. Regards, John
12:28 The generator is already connected to ground through the BNC of the coax cable between your scope and generator. That's why you didn't see a difference when you clipped on or removed the ground wire to the BNC at the back.
It is a decent old scope. Fixed the 757 a while back. Did not get a chance to video the repair. So much going on. A month ago it came back, CPU failure. So I guess we get a chance to work on it again. I let him borrow the 747 for now.
Glad you mentioned that because when you flipped the old non-polarised plug it did not show a change,so I did not think about where the hot and neutral should go.
Darn Buddy, I was really looking forward to watching those filter caps blow up. I haven't seen one blow for 2 or 3 months now LOL. Great job on fixing this issue. Like you said, now you won't have to worry about blowing any test gear up. Good job. Thank you! 73 de K7RMJ Frank
Thanks Frank. Never know what will happen after doing a mod to equipment like this. It is one of those crass your fingers and hope something will happen lol. Thanks for watching my friend.
I've just got a used FY3200S on eBay. So glad I happened upon this video! Where is UL when we need them? I used this a couple of times on my HP scope and found it faultless in its signal generation. I'm glad it didn't hurt the scope. It will get your fix before I use it again. Thanks for this great video!
You can also connect a little neon lamp in parallel with the extra "ground switch" , when the "ground switch" is in the off position, the neon lamp lights up as a "no ground" indicator.
Tks Buddy that you Bring this up to your viewers , Yes that power supply needs to be updated . and 3 prong plug cord..and I did what you said, changing the power supply to linear type.. hay thats a nice scope seen Hummmmm it keeps right on burring and kick'en tks Buddy 73's
Simple solution to fix the leakage problem. Sent the email about it because I thought you would want to know about the problem. Only thing to remember is if you plug this into a GFI protected outlet it may trip the GFI breaker. Have seen that happen in some situations.
The Radio Shop I have run into that frequently when putting 3 prong cords onto old tube type radios. The GFI senses the leakage and does exactly what it's supposed to do, trip.
Thanks, Buddy for posting this. I may try adding a 3-prong plug to mine. I'm still curious to see if I get any interference from the switchmode power supply or that safety cap. I guess that will be the next test on this thing. Also, were you able to get the FSK/ASK to work? I haven't had much luck with it. The software seems easy to use, but a bit buggy. Anyway, Thanks for all your great videos! They are very helpful to all of us! I know how much extra time they take for you to make. 73's Tony - W3XTB
Hi Tony, I do want to get more testing on this unit. Curious about noise also. And now after my mod I did I wonder about ground loops. I have not played around with software yet because I was a little worried over plugging it into my usb port with that voltage on it. Now that I have that under control I think I will. Thanks for taking time to stop by. Will get more testing done soon.
I appreciate this video is a year old now but, as you have not posted anything later, I wondered whether you had since carried out any further testing and confirmed that everything continues to work as it should with no ground loops or other adverse effects?
This unit has performed flawlessly since I put it on the bench. I use it at least once a week with out any problems. If anything goes go wrong you can bet there will be a video on it. As of now nothing negative to say.
As there is one fuse, and if using the original connector, the fuse could be on the neutral not the phase line, meaning it would not blow with an earth fault.
Just got one of these until I can upgrade. Thanks for the video. Made the ground modification. Didn’t put a switch in yet. Have you ever found an instance to have to float?
Wow. video scared me some. I think maybe the best fix for it would be to chuck it in the trash, wear insulating shoes while doing it, lol. Love the channel and video's. I made very low THD audio sig gen few years ago, I used a little transformer from a old wall wart. Kinda hard to doubt that isolation. I gather the Hitachi is the sacrificial lamb, just in case.
Hi, I enjoyed your video on the signal generator. Recently purchased one from eBay, waiting for it to arrive. Good thing you found a remedy for the issue. I just need to really understand why you set up a switch for ground and float. Would you be so kind to explain it in more detail? Thank you very much for your time.
Hey, Buddy I noticed that they did put an "earth ground" symbol on the back connectors. Guess they meant for it to be connected to earth ground and you just finished the job for them 🤓
Think Steve over on the SDG Electronics channel covered his mods to the Bangood branded generator about a year ago in a couple of videos. As I recall he swapped out the power supply and put a isolated USB I/O in there as well to combat the issues you've identified. 73 - Dino KL0S
Hey Buddy thanks for this information. I was planning on buying one of these like this in the future except the one from the same company that has a bigger screen, goes up to 60mHz, and displays wave forms, but I'm guessing it would have a similar problem. So the question I have is what signal generator would you recomend that can do everything including sweeping in the $100-150 range? (if there is one) or a little more if not.
I am not sure if the 60MHz version has this problem or not. Will be something I will look into. As far as recommendations on a function gen these will be ok for hobbyist. But really depends on if you need RF signal or function signal. There are some cheaper ones on the market. Let me know. Or give me an email.
I'll definitely do this mod. to mine, will check for stray voltage first, in case manufacturer fixed it between your video and now, I'll put 3 core cord thru the back and use a clamp type grommet, and simply blank off original socket cutout.. Thanks..
This mod is interesting and helpful, I own one of these feeltech signal generators and I was able to purchase it at a substantial value. One point though, and correct me if I'm wrong, but doesn't this mod result in the 45 volts being "drained" through ground (which is tied with neutral in the US)? Thus this solution being effective depends on the integrity of the ground wiring within the building the unit is operated. In an older home not upgraded to 3 wire outlets this mod would have no effect. (of course alternatively you could 'key' the AC plug in the back and change the power cord for a polarized one). And, perhaps more importantly, grounding wiring in a home is not intended for continuous discharge of unwanted currents. Sure, in a properly maintained and wired to code house the electrical system could handle the constant discharge, but it is not intended for that as far as I know.
I can partially answer that question ..... Yes if your house has a 3 wire system , then the added wire would be earth ground ..... If your house or some receptacles are still old style 2 wire then a 3 prong adapter with a green wire coming out of it screwed to the middle plate screw would work........ You don't have to ask me how I know this LOL....
I think by connecting the two rear jacks together you may have created a ground loop that could inductively pick up noise. Running your power cord ground to the power supply only would avoid any loops. Realistically this is not a real problem since any magnetic field strong enough to induce currents in a ground loop would interfere directly with the other electronics in the unshielded box. Building an analog supply would be a good idea since this unit probably radiates noise with its unshielded power supply. Anyways, thanks for the video!
I agree. Why I mention further testing was needed. At least the shock hazard is gone. Will do more testing with this unit and see how it stacks up. I was concerned that there may be a ground loop issue. But like you said no shielding at all in this thing. Thanks for watching.
You definitely took care of the most important thing first. I had a headphone amp with a similar (self-created) ground loop that tested my troubleshooting skills. I almost always learn something from your videos and this one made me want to go check a couple of AC powered instruments I have for similar problems. Thanks again.
Could you safely remove the "safety" capacitor bridging the AC to DC sides? Or replace it/them with good quality XY caps? Don't know what effect that would have - perhaps RFI?
Everyone pretty much has a regulated supply for their CB Radios for test or Base Radio usage - which could be used as a supply voltage,then you would just need a regulator board for the different voltages for the Generator.
A small 110 volt isolation transformer will fit easily in the case. Take off the label saying it will run on 220 also. You can still install your float or grounded switch.
Even before see this Video i had planned the very same mod when my one of these arrives from ebay, it makes perfect sense, specially with the mains here in New Zealand being 240v so leaks to the BNC could be a very major safety concern, seems great minds think the same.
I was thinking that also, but Steve at SDG electronics gives theory as why this would not eliminate the issue. But still would not hurt to isolate the mains the way you mention. That is extra protection!.
I did this same mod when my FY3200S came in. It seemed a much easier mod than replacing the entire power supply. The unit does not seem to care that it now has an earth ground. Perhaps this is why all computer power supplies have the earth ground.
P.S. If you still have problem reverse the plug going into unit ( this was an old trick we use to do when playing in clubs and we would get a shock when we touched our guitar's )
Thanks for sharing this issue, I do wonder why they don't simply have a 3 pin IEC, so there is an earth to take care of the leakage, so common these days with almost everything having a switch mode power supply.
Thanks for watching. I really think their goals is to produce mass quantities of cheap stuff. Ignoring safety concerns. I am sure one day they will get it right. Remember the Japanese. At first it was crap, then became the best you could buy.
Better switch mode power supplies do not have this leakage problem. Better switch mode power supplies have about 1500V of isolation between the input and output, and are tested to verify it (that's what the HI POT test sticker you may have seen on a power supply means).
Buddy, the electrical market is being flooded with Chinese products that are sneaked in without the UL (Underwriter's Laboratory) seal of approval attached. Many of these are LED lighting fixtures. If a product doesn't have a UL sticker on it, I wouldn't touch it with a powder puff! Not that I'm worried about getting electrocuted, but my customers could take my home and everything I own if they have someone electrocuted by non-UL products that I might have installed. The electrical inspectors would have a field day if one was caught installing the non-UL stuff. 73...Dan w4mnc
You are right Dan, have to be careful of what you install in folks stuff these days. Lets remember this, we saw the same thing years ago with the Japanese. Now the best stuff is made in Japan. Not sure how long the transaction will take for the Chinese market to build quality into their products but think it will happen one day. It is up to us to point these mistakes out. I have contacted the maker with the issues. Just have to wail and see if they listen. Thanks Dan
All I did to mine was to buy a good AMERICAN power cord that has a polarized plug and fits the AC input and whala! no voltage to speak of at ground of BNC
Hey Buddy good catch! I find most of the Chinese stuff is not well made. I some countries like ours this would not pass mains safety. As for the power supply, nothints beats a good liner power supply.
Yeah. When you asked me about this on your other video I couldn't figure out for the life of me how I'd have mains voltage anywhere inside or outside the unit.
The Radio Shop Actually, this is does not appear to be true!! I have a KMoon DDS Signing Gen with a wall-wort (so DC 5V in). I just checked it with my multimeter and, sure enough, with the power on I get 43.5 V AC on the terminals!!! How can this be possible?
Actually, just plug in the USB. I replicated the voltage leak just like the video and after plugging in USB the problem was gone. Power on or power off; AC and DC metered; host computer on or off; two different multi-meters. Problem solved. It gets ground through USB.
AC to ground is way better than AC short to neutral. your RCD will trigger and save your device and house from being on fire and exploding... or you completing the circuit between live AC and ground with the appropriate consequences. oh wait you don't have those mandatory in the USA...
This is my PSU modification: i.postimg.cc/RMx5HzLz/20201109-044733.jpg 1x 2x12V transformer, with LM7812, LM7912, LM7805, solid capacitors and 100nF in parralel on input and output of the ICs. Also the signal generator feels heavier.
This has more to do with the rather 'unique' way the US grid is built that the piece of equipment on itself. The US, uses a split-phase system on the level of the domestic distribution rather than a true monophase or a true 3 phase system. This is mainly due to a nasty legacy that can be brought back to the AC-DC wars between Edison and Tesla (Westinghouse) Rather than getting rid of this strange affair while there was still time, distributors have been building on it ever since. This all results in a system where you have something that can almost be called 'polarised AC' Beggars belief, doesn't it? If in such a case, one puts the ground at the same level as the 'zero-conductor' (it isn't a true zero conductor to start with...) you get these odd and sometimes dangerous situations. In a true 3 phase system the ground and neutral are also at the same potential, but not at the level of the individual house. It is even hard to do at the level of the powerplant as there is never a true and equal division between the phases. Playing around with grounded plugs and such will not do much good in this case. That all said they power switch should be dual pole and not single pole as it obviously is in this case. Paddy
Does this actually mean us folks from Europe wouldn't have this issue with leaking mains current? Sorry for stupid question if it is one, but I am still a beginner in this whole electronics thing and these little function generators are a nice starter instrument in my eyes.
In the context of a standard 120V receptacle, which is what this device is plugged into when operated in the USA, split phase has nothing to do with it. Split phase ONLY comes into play when we are talking about a 240V receptacle, and rest assured, anything designed to operate from a 240V power source in the USA is designed (or should be) to take into account the fact that both legs are hot with respect to ground. The standard 120V receptacle in the USA contains 3 wires: A ground, a neutral, and a hot. The ground and neutral are in fact connected together at the "service disconnecting means" which is the only place they are connected together. The issue with this device does not go away when operated on a 240V receptacle in the UK, which presumably also has a ground, a hot, and a neutral. Since you use RCDs there and since they do trip when there is a ground fault, I can be reasonably sure that one side of your transformer secondary is connected to ground; it isn't floating. Because the device, when connected to a 240V receptacle in the UK, is connected to a power source one leg of which is connected to ground, you will in fact have the same problem with voltage on the BNC connectors as when it is connected to a 120V receptacle in the USA. The only difference is that the measured voltage on the BNC connectors will be twice as high, due to the 240V supply.
@@MladenMijatov No, it does not mean that you won't have this issue with leaking mains current, unless the transformer secondary supplying your electrical service is floating (not connected to ground). I'm not aware of any place where transformer secondaries are left floating as a normal installation procedure...
Chinese engineers are fixated on Switched Mode Power Supplies for everything! Probably on account of a linear supply's extra heat dissipation, and the heavier mains transformer. But less efficient linear ones are far cleaner noise-wise, much simpler in design, and more reliable. For low power supplies such as in this unit, their poorer efficiency is not really a big factor, compared with the SMPS RF noise, both radiated and on the signal line. In fact I bought a similar JDS 6600 specifically so I could use an external 5V linear supply to power it. (Hopefully the JDS's internal +/-15V boost converters have been designed to minimise RF noise, because +/-15V is essential to get the required output signal voltage swing.)
The sad part is that there is PLENTY of information on the internet about how secondary distribution in the US works, yet you chose not to get educated. :(
Good information for us guys that are on a budget. Will help make this budget equipment safer.
Cheap is good. But safety is a must and first on the list. Thanks
Excellent stuff and great, practical genius fix. With all the logical, necessary, cautious steps to get there. Spot on. First class. This EE thanks you.
Thanks Greg for the kind words.
Followed all your instructions and it worked, ground showed only a few ohms with a beep, so all good. Thank you very much for your help.
just ordered one today ,if I had known this I wouldn't have ordered it . When it comes in I'll check it out and make adjustments as shown to it .
Best way to solve the AC problem with this unit. I plan to do the same. Thanks for the video inspiration.
Thanks for video. This inspired me to immediately fix up my FY3200. My solution was just to cut the end off of a computer power cord. Remove the old socket from the FY3200. Thread the cord thru the rectangular hole. Make up some "creative" strain relief (involves hot glue!), and solder the wires. I used one of the ground lugs on back BNC connectors as a common point to collect up some ground connections.
Way to go, that should work just fine. Thank you for watching.
At 15:35 you can see a surface mount resistor between the ground trace and a neighboring pad on the right hand side, makes me wonder if that is the cause of the leakage.
I will have a look at it. But from what others are saying it is the protection caps causing the problem
I'll implement this circuit until I have a Linear Power Supply. Great Job!
Beautiful! What were they thinking? Somebody in the design department needs to go back to school. Great job Buddy and I love your fix👍
no it has a dual function It is sold also as electrical stimulator
Hey Buddy... Thanks for the video. It was very interesting. And... I noticed the Eico switch sitting there on the bench!
Thanks, glad it is helpful. Yes I am putting the switch together and recording the process. just takes time. Will be in a future video. Thanks for watching.
Excellent Educational Video, Buddy. Thank you again for your difficult work.
Thank you for watching. Easy stuff my friend.
Brilliant solution. I'd love to see the linear supply, if you'll design and install one. Thanks for sharing this!
Thank you.
th-cam.com/video/FF2lk03mNto/w-d-xo.html Here is a TH-cam vid on a designed and replacement power supply. reasonable priced new PS
Good, easy repair, thanks for posting. As your switch is out of site on the back panel, I would advise adding an LED on the front panel showing when your device is in Float or Grounded mode (I tend to forget such things when they're out of site).
Also, I have a competing product called an Instek MHS-5200A that's almost identical in appearance but confines its switching mode PS to a 5V, 200ma wall-wart. It therefore doesn't have the AC ground issues your unit has, but hash and ripple are no doubt still there. For that I plan to add a battery and LDO regulator to eliminate all switching problems entirely.
Thanks for sharing that information. I was thinking after reading this to just change the channel LEDS to dual green/red. So when in ground mode they would be green and when floating turn red. Should be an easy mod. Thanks for sharing.
Sincerely You
Hey Buddy, great video, you have made the device safe for use and service. I do think it would be much better as you said to make a good linear supply or even one off the shelf that fits well. Thank you my friend. Rock on.... Joel
Thanks Joel and good to see you. Yes a good redesigned supply would be a great way to go.
SGS Electronics has a great video on building a Linear Power supply.
another option could be to place a single +12VDC socket on the back panel and get +5VDC from that with a cheap dc to dc converter
in this way the main power supply will be completely external and could be a good linear one
Good job good Idea these old tube type base stations will shock the fire out of you if you touch the mike plug . I learned the hard way!!
Hello again Buddy ! ... I am still on catch up with all your vids so I am late posting sorry. I also have that Rigol scope and I am pretty confident that it would have been OK as the BNC's ground is actually earthed. Can't blame you for not trying it as doubt always plays tricks with your mind. Have a nice day and keep up the good work.
Thanks Andy
I was not aware that safety caps will short. I thought they were designed to open. Live and learn. BTW...I have this unit and will be making the change. Thanks, my friend.
Regards,
John
Thanks John. Well normal ones open but these....well lets say they are not the best.
Great video Buddy. You may have saved the lives of both humans and devices.
Thanks Todd, safety is number one.
12:28 The generator is already connected to ground through the BNC of the coax cable between your scope and generator.
That's why you didn't see a difference when you clipped on or removed the ground wire to the BNC at the back.
He is right.
Very nice vid buddy, learned a lot... Thanks.
Thanks
Nice Hitachi scope! I have a v-212 as well. Solid unit.
Still waiting for the Yaesu 757 video :)
It is a decent old scope. Fixed the 757 a while back. Did not get a chance to video the repair. So much going on. A month ago it came back, CPU failure. So I guess we get a chance to work on it again. I let him borrow the 747 for now.
Thanks for the video. Now I can do the same to mine. You made it look simple. 73's
Really simple to do yes. Just make sure the hot side of the AC is on the fuse. Thanks Robert
Glad you mentioned that because when you flipped the old non-polarised plug it did not show a change,so I did not think about where the hot and neutral should go.
Glad to here that .
Please tell where you found the small power connector on the internet but used the one you have. Thank you.
Darn Buddy, I was really looking forward to watching those filter caps blow up. I haven't seen one blow for 2 or 3 months now LOL. Great job on fixing this issue. Like you said, now you won't have to worry about blowing any test gear up. Good job. Thank you! 73 de K7RMJ Frank
Thanks Frank. Never know what will happen after doing a mod to equipment like this. It is one of those crass your fingers and hope something will happen lol. Thanks for watching my friend.
All I can say Buddy is Excellent!!!!!
I've just got a used FY3200S on eBay. So glad I happened upon this video! Where is UL when we need them? I used this a couple of times on my HP scope and found it faultless in its signal generation. I'm glad it didn't hurt the scope. It will get your fix before I use it again. Thanks for this great video!
You can also connect a little neon lamp in parallel with the extra "ground switch" , when the "ground switch" is in the off position, the neon lamp lights up as a "no ground" indicator.
Have you checked out the 60Mhz model 6600-60 to see how it tests for radio repair work?
Have not got that model yet. Will have to see
Thanks Buddy - hope you had a good Thanksgiving.
Tks Buddy that you Bring this up to your viewers , Yes that power supply needs to be updated . and 3 prong plug cord..and I did what you said, changing the power supply to linear type.. hay thats a nice scope seen Hummmmm it keeps right on burring and kick'en tks Buddy 73's
Thanks Dale, Yes thought you may have seen that scope before:)
So glad its in a Good home and at good uses
Good idea the old tube types radio's mic's would shock you for sure!!!
Thank you very much i love yur help
Simple solution to fix the leakage problem. Sent the email about it because I thought you would want to know about the problem. Only thing to remember is if you plug this into a GFI protected outlet it may trip the GFI breaker. Have seen that happen in some situations.
Thanks for that link Mike. I put it in the show more tab related to you . Will have to test the GFI to see if you are on to something.
The Radio Shop
I have run into that frequently when putting 3 prong cords onto old tube type radios. The GFI senses the leakage and does exactly what it's supposed to do, trip.
Nice fix Buddy.. Shame the little unit had to be fixed at all but hey, at least it makes for a good video :)
Cheers friend
John
Thanks for stopping in John. Well you know the Chinese. They build it, we fix it. :-)
Great modification. I'm concidering buying one of these units, you would think by now the manufacture would have cured this problem.
Will that unit provide the Frequency and 1K Tone for receiver signal tracing?
Thanks, Buddy for posting this. I may try adding a 3-prong plug to mine. I'm still curious to see if I get any interference from the switchmode power supply or that safety cap. I guess that will be the next test on this thing. Also, were you able to get the FSK/ASK to work? I haven't had much luck with it. The software seems easy to use, but a bit buggy. Anyway, Thanks for all your great videos! They are very helpful to all of us! I know how much extra time they take for you to make.
73's
Tony - W3XTB
Hi Tony, I do want to get more testing on this unit. Curious about noise also. And now after my mod I did I wonder about ground loops. I have not played around with software yet because I was a little worried over plugging it into my usb port with that voltage on it. Now that I have that under control I think I will. Thanks for taking time to stop by. Will get more testing done soon.
xraytonyb I
Cool just got one.
Can this unit be used to align AM tube radios.
I appreciate this video is a year old now but, as you have not posted anything later, I wondered whether you had since carried out any further testing and confirmed that everything continues to work as it should with no ground loops or other adverse effects?
This unit has performed flawlessly since I put it on the bench. I use it at least once a week with out any problems. If anything goes go wrong you can bet there will be a video on it. As of now nothing negative to say.
As there is one fuse, and if using the original connector, the fuse could be on the neutral not the phase line, meaning it would not blow with an earth fault.
You got that right. You would think that since they used a non polarized plug they would have installed 2 fuses.
Just got one of these until I can upgrade. Thanks for the video. Made the ground modification. Didn’t put a switch in yet. Have you ever found an instance to have to float?
Wow. video scared me some. I think maybe the best fix for it would be to chuck it in the trash, wear insulating shoes while doing it, lol. Love the channel and video's. I made very low THD audio sig gen few years ago, I used a little transformer from a old wall wart. Kinda hard to doubt that isolation. I gather the Hitachi is the sacrificial lamb, just in case.
Yes it is scary stuff out there. Have to be careful as some of this stuff and damage your high end equipment. Thanks for watching
Hi, I enjoyed your video on the signal generator. Recently purchased one from eBay, waiting for it to arrive. Good thing you found a remedy for the issue. I just need to really understand why you set up a switch for ground and float. Would you be so kind to explain it in more detail? Thank you very much for your time.
For what reason you would need to float it its not better just Grundig with no switch to make sure the is no mistake done??
Buddy, does this generator produce AM modulation? Could it be used as a CB receive tester?
Great work!!!!!
Hi, if i have not ground connection at home..how can i fix that problem ? Regards ALX
Hey, Buddy
I noticed that they did put an "earth ground" symbol on the back connectors. Guess they meant for it to be connected to earth ground and you just finished the job for them 🤓
Yes ironic isn't it. They take the time to do screen printing but do not take the time to complete the circuit. Major face palm.
@@TheRadioShop That's Chinese for you, quick money, mass production.
Think Steve over on the SDG Electronics channel covered his mods to the Bangood branded generator about a year ago in a couple of videos. As I recall he swapped out the power supply and put a isolated USB I/O in there as well to combat the issues you've identified. 73 - Dino KL0S
Yes watched his video this past week end. Good stuff. I linked his repair video in the show more tab. Thanks Dino
Duuuh, would have known that if I'd simply looked in the notes! Sorry 'bout that!
No problem Dino. I planned to mention it in the video but slipped my mind.
Hey Buddy thanks for this information. I was planning on buying one of these like this in the future except the one from the same company that has a bigger screen, goes up to 60mHz, and displays wave forms, but I'm guessing it would have a similar problem.
So the question I have is what signal generator would you recomend that can do everything including sweeping in the $100-150 range? (if there is one) or a little more if not.
I am not sure if the 60MHz version has this problem or not. Will be something I will look into. As far as recommendations on a function gen these will be ok for hobbyist. But really depends on if you need RF signal or function signal. There are some cheaper ones on the market. Let me know. Or give me an email.
Nice!
Thanks
I'll definitely do this mod. to mine, will check for stray voltage first, in case manufacturer fixed it between your video and now, I'll put 3 core cord thru the back and use a clamp type grommet, and simply blank off original socket cutout.. Thanks..
This mod is interesting and helpful, I own one of these feeltech signal generators and I was able to purchase it at a substantial value.
One point though, and correct me if I'm wrong, but doesn't this mod result in the 45 volts being "drained" through ground (which is tied with neutral in the US)? Thus this solution being effective depends on the integrity of the ground wiring within the building the unit is operated. In an older home not upgraded to 3 wire outlets this mod would have no effect. (of course alternatively you could 'key' the AC plug in the back and change the power cord for a polarized one).
And, perhaps more importantly, grounding wiring in a home is not intended for continuous discharge of unwanted currents. Sure, in a properly maintained and wired to code house the electrical system could handle the constant discharge, but it is not intended for that as far as I know.
I can partially answer that question ..... Yes if your house has a 3 wire system , then the added wire would be earth ground ..... If your house or some receptacles are still old style 2 wire then a 3 prong adapter with a green wire coming out of it screwed to the middle plate screw would work........ You don't have to ask me how I know this LOL....
Could you have changed the safety caps out for better quality caps ?
A few others have already tried that. I have been watching more videos on this issue. The smps is crappy at best.
HI Buddy, by safety cap do you mean a cap in series with the incoming ac? Thanks Dave
I think by connecting the two rear jacks together you may have created a ground loop that could inductively pick up noise. Running your power cord ground to the power supply only would avoid any loops. Realistically this is not a real problem since any magnetic field strong enough to induce currents in a ground loop would interfere directly with the other electronics in the unshielded box. Building an analog supply would be a good idea since this unit probably radiates noise with its unshielded power supply. Anyways, thanks for the video!
I agree. Why I mention further testing was needed. At least the shock hazard is gone. Will do more testing with this unit and see how it stacks up. I was concerned that there may be a ground loop issue. But like you said no shielding at all in this thing. Thanks for watching.
You definitely took care of the most important thing first. I had a headphone amp with a similar (self-created) ground loop that tested my troubleshooting skills. I almost always learn something from your videos and this one made me want to go check a couple of AC powered instruments I have for similar problems. Thanks again.
Could you have earthed just the power supply pcb. ???
Yes you could, it has grounds going to the other boards.
Could you safely remove the "safety" capacitor bridging the AC to DC sides? Or replace it/them with good quality XY caps? Don't know what effect that would have - perhaps RFI?
does make sense
Thanks
Everyone pretty much has a regulated supply for their CB Radios for test or Base Radio usage - which could be used as a supply voltage,then you would just need a regulator board for the different voltages for the Generator.
That is also a great option.
A small 110 volt isolation transformer will fit easily in the case. Take off the label saying it will run on 220 also. You can still install your float or grounded switch.
Even before see this Video i had planned the very same mod when my one of these arrives from ebay, it makes perfect sense, specially with the mains here in New Zealand being 240v so leaks to the BNC could be a very major safety concern, seems great minds think the same.
You could isolate the mains by fitting two small identical transformers wired back to back in the mains input feed.
I was thinking that also, but Steve at SDG electronics gives theory as why this would not eliminate the issue. But still would not hurt to isolate the mains the way you mention. That is extra protection!.
I like the switch could come into play down the line
Agreed. Thanks
Seems like I read in the NEC that earth ground wiring shall not be switched or have a means of disconnecting. Just saying.
I did this same mod when my FY3200S came in. It seemed a much easier mod than replacing the entire power supply. The unit does not seem to care that it now has an earth ground. Perhaps this is why all computer power supplies have the earth ground.
I had 90v on mine before I modded it! Its now 4v and just 19 microamps.
Apart from the "polarity" the quality of the mains cable is bad. Mine had damaged isolation and gave a short! Swap immidiatly pse!
P.S. If you still have problem reverse the plug going into unit ( this was an old trick we use to do when playing in clubs and we would get a shock when we touched our guitar's )
Thanks for sharing this issue, I do wonder why they don't simply have a 3 pin IEC, so there is an earth to take care of the leakage, so common these days with almost everything having a switch mode power supply.
Thanks for watching. I really think their goals is to produce mass quantities of cheap stuff. Ignoring safety concerns. I am sure one day they will get it right. Remember the Japanese. At first it was crap, then became the best you could buy.
Better switch mode power supplies do not have this leakage problem. Better switch mode power supplies have about 1500V of isolation between the input and output, and are tested to verify it (that's what the HI POT test sticker you may have seen on a power supply means).
haha! thanks man, you just saved me 50$
Some of the Old Test Equipment had the Grounded Mickey Mouse AC Power Plug.
The engineers should be required to test it while standing in a bathtub...
LOL, that would do it!
Buddy, the electrical market is being flooded with Chinese products that are sneaked in without the UL (Underwriter's Laboratory) seal of approval attached. Many of these are LED lighting fixtures. If a product doesn't have a UL sticker on it, I wouldn't touch it with a powder puff! Not that I'm worried about getting electrocuted, but my customers could take my home and everything I own if they have someone electrocuted by non-UL products that I might have installed. The electrical inspectors would have a field day if one was caught installing the non-UL stuff. 73...Dan w4mnc
You are right Dan, have to be careful of what you install in folks stuff these days. Lets remember this, we saw the same thing years ago with the Japanese. Now the best stuff is made in Japan. Not sure how long the transaction will take for the Chinese market to build quality into their products but think it will happen one day. It is up to us to point these mistakes out. I have contacted the maker with the issues. Just have to wail and see if they listen. Thanks Dan
It would probably take only one good lawsuit for wrongful injury to correct the problem.
All I did to mine was to buy a good AMERICAN power cord that has a polarized plug and fits the AC input and whala! no voltage to speak of at ground of BNC
Hey Buddy good catch! I find most of the Chinese stuff is not well made. I some countries like ours this would not pass mains safety. As for the power supply, nothints beats a good liner power supply.
Thanks Henry, you are correct, this would never pass in the USA.
Luckily mine uses a wall wart power supply.
Oh you are lucky! That solves the problem
Yeah. When you asked me about this on your other video I couldn't figure out for the life of me how I'd have mains voltage anywhere inside or outside the unit.
LOL. You have nothing to worry with on that one.
What is inside the Generator to separate the different voltages - where others could convert theirs to a simple Wal-wart supply?
The Radio Shop Actually, this is does not appear to be true!! I have a KMoon DDS Signing Gen with a wall-wort (so DC 5V in). I just checked it with my multimeter and, sure enough, with the power on I get 43.5 V AC on the terminals!!! How can this be possible?
Being lazy like I am I would go to Mouser and buy a Meanwell power supply, install it in the case and be done with it.
I am going to explore that option as well in the future. You know, Just for our lazy friends :-)
Actually, just plug in the USB. I replicated the voltage leak just like the video and after plugging in USB the problem was gone. Power on or power off; AC and DC metered; host computer on or off; two different multi-meters. Problem solved. It gets ground through USB.
But do you really want it grounded through your computers USB?
AC to ground is way better than AC short to neutral. your RCD will trigger and save your device and house from being on fire and exploding... or you completing the circuit between live AC and ground with the appropriate consequences. oh wait you don't have those mandatory in the USA...
This is my PSU modification: i.postimg.cc/RMx5HzLz/20201109-044733.jpg
1x 2x12V transformer, with LM7812, LM7912, LM7805, solid capacitors and 100nF in parralel on input and output of the ICs. Also the signal generator feels heavier.
Would making home made linear power supply like this one solved the problem? www.vwlowen.co.uk/arduino/xr2206/page3.htm
That would be a very good idea
This has more to do with the rather 'unique' way the US grid is built that the piece of equipment on itself.
The US, uses a split-phase system on the level of the domestic distribution rather than a true monophase or a true 3 phase system.
This is mainly due to a nasty legacy that can be brought back to the AC-DC wars between Edison and Tesla (Westinghouse)
Rather than getting rid of this strange affair while there was still time, distributors have been building on it ever since.
This all results in a system where you have something that can almost be called 'polarised AC' Beggars belief, doesn't it?
If in such a case, one puts the ground at the same level as the 'zero-conductor' (it isn't a true zero conductor to start with...) you get these odd and sometimes dangerous situations.
In a true 3 phase system the ground and neutral are also at the same potential, but not at the level of the individual house.
It is even hard to do at the level of the powerplant as there is never a true and equal division between the phases.
Playing around with grounded plugs and such will not do much good in this case.
That all said they power switch should be dual pole and not single pole as it obviously is in this case.
Paddy
Very good explaination
Does this actually mean us folks from Europe wouldn't have this issue with leaking mains current? Sorry for stupid question if it is one, but I am still a beginner in this whole electronics thing and these little function generators are a nice starter instrument in my eyes.
In the context of a standard 120V receptacle, which is what this device is plugged into when operated in the USA, split phase has nothing to do with it. Split phase ONLY comes into play when we are talking about a 240V receptacle, and rest assured, anything designed to operate from a 240V power source in the USA is designed (or should be) to take into account the fact that both legs are hot with respect to ground.
The standard 120V receptacle in the USA contains 3 wires: A ground, a neutral, and a hot. The ground and neutral are in fact connected together at the "service disconnecting means" which is the only place they are connected together.
The issue with this device does not go away when operated on a 240V receptacle in the UK, which presumably also has a ground, a hot, and a neutral. Since you use RCDs there and since they do trip when there is a ground fault, I can be reasonably sure that one side of your transformer secondary is connected to ground; it isn't floating.
Because the device, when connected to a 240V receptacle in the UK, is connected to a power source one leg of which is connected to ground, you will in fact have the same problem with voltage on the BNC connectors as when it is connected to a 120V receptacle in the USA.
The only difference is that the measured voltage on the BNC connectors will be twice as high, due to the 240V supply.
@@MladenMijatov No, it does not mean that you won't have this issue with leaking mains current, unless the transformer secondary supplying your electrical service is floating (not connected to ground). I'm not aware of any place where transformer secondaries are left floating as a normal installation procedure...
Chinese engineers are fixated on Switched Mode Power Supplies for everything! Probably on account of a linear supply's extra heat dissipation, and the heavier mains transformer. But less efficient linear ones are far cleaner noise-wise, much simpler in design, and more reliable. For low power supplies such as in this unit, their poorer efficiency is not really a big factor, compared with the SMPS RF noise, both radiated and on the signal line. In fact I bought a similar JDS 6600 specifically so I could use an external 5V linear supply to power it. (Hopefully the JDS's internal +/-15V boost converters have been designed to minimise RF noise, because +/-15V is essential to get the required output signal voltage swing.)
this is nothing to do with the unit , its to do with the crappy grid in the US .
Plenty of reviews on youtube of folks having this issue with 240 mains
The sad part is that there is PLENTY of information on the internet about how secondary distribution in the US works, yet you chose not to get educated. :(
What a loud of rubbish, man or mouse, ever been to England. Mein works okay 6 years ago. Fake news?
What the fuck are you on?