It's certainly possible the designer made a mistake - especially for electrolytic capacitors, which are rated in such a manner that they "seem" fine unless you do the math. For instance, in a system that only gets "warm", component temperature ratings are generally not a concern, except for electrolytic capacitors. Even a cheap capacitor will typically be rated for 85 degrees, which seems like it should have lots of margin until one reads the fine print and discovers the lifetime is only 1000 hours at this temperature! I know it was a surprise to me as a young designer long ago when I saw that components were specified with such low lifetimes (hard to imagine an application where 1000 hours is sufficient!). Once the derating for temperature and working voltage are applied one discovers that the lifetime is far less than expected.So did the designer make a mistake by not specifying a better C8? Did the designer get second-guessed by the purchasing department, who patted themselves on the back for saving a few pennies by making a "better" choice?
Some may say it's planned obsolescence but I don't buy that. It's my nature to embrace Hanlon's Razor: "Never attribute to malice that which is adequately explained by stupidity." I think stupidity is a far more likely explanation than any evil plan.
Great work. Would you care to include the schematics and layout too?I had the same problem but replacing the Caps didn't solve the problem for me. I reverse engineered the PCB to build a new one with (mostly) new components. If someone else comes across this thread; the gerber files can be found attached here. Included is a BOM with part numbers for Mouser and Digikey.
There are a few important steps to follow though:
1. On the bottom side of the original PCB there are some additionaly tinned up tracks. This is sometimes done where PCB-tracks are too narrow for the expected amount of electricity. I did adopt this 1:1 without checking whether it is really required. Before assembling any part of the PCB you should tin up these tracks, too.
2. I kept the Component designators the same as on the original board. It didn't make much sense to me there, so don't expect to find a continuous numbering here.
3. There is a 74.2kΩ resitor (R211) on the original board. Resistors of this value can be difficult to get at times, so I added the option to use two seperate resitors of 68kΩ and 6.2kΩ respectively (R211:A and R211:B). Only populate either the R211 resitor or the two R211:A/R211:B resistors. Do not populate all three of them!
4. You will need to reuse the two transformers TR1 & TR2 (labelled as "JBC-983-EEL-19" and "MP-011/220V" or "MP012-110V" (depending on where you are in the world)) as well as the three heatsinks.
5. The two Fuses (F1 & F2) need to be protected from accidentally shorting to other parts by enclosing them in heat shrink tubing of an appropriate size.
All the files and information provided here are provided free of charge with NO WARRANTY WHATSOEVER. Working with electronics is dangerous and can be lethal. You and only you are responsible for any damage and/or injuries by any use of the files and/or information given here!
Good to hear that you got it working. Too bad you replaced all the caps at once. It would have been useful to know which one was causing the problem.I have the same cooler and the power supply was not switching. I replaced all the electrolytic caps and it works again. Thanks for all the previous comments.
Agreed, but it was quicker to just replace all than to do one, test, do another, test, etc. I suspect it was the oneGood to hear that you got it working. Too bad you replaced all the caps at once. It would have been useful to know which one was causing the problem.
True, but it was just quicker to replace all rather that one at a time with testing in between.Good to hear that you got it working. Too bad you replaced all the caps at once. It would have been useful to know which one was causing the problem.
Agreed, but it was quicker to just replace all than to do one, test, do another, test, etc. I suspect it was the one or several around the transformers as the converter was not switching.Good to hear that you got it working. Too bad you replaced all the caps at once. It would have been useful to know which one was causing the problem.
This thread is for success stories only. Please start a new thread.Alright this forum has helped me so much. I gave a Kalamera KR-28ASS wine cooler that has an MP-012 board. When I got it it wasn’t working and the board had the red and green led lowly lit and flickering and making a staticky noise. Fans were not running and the front temp control display was not working.
I replaced all the capacitors except for the 2 large 200V 120uf ones (should I replace these?). Now the wine fridge is working, the fans are running and the front display is working also.
I set the temp to 55 on the display and let the fridge cool, when the temp gets close to that value I hear the fan slow down, and when I look at the board, the red led is pulsing bright to dim, and the green led is blinking on/off. Is this normal? (Also if the ambient light is turned on on the inside of the fridge, it will flicker slightly also when the fan is slowed)
Another thing I noticed is that the display reads at least 10degrees cooler that inside the fridge. Is there a way to calibrate/fix this? Since if I set to 55, the fridge will stop cooling and the inside is actually at 65.
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