In general, I am not too picky about finding the exact replacement. What I would want to match are:

1) value of capacitance
2) operating voltage. You could even go with higher voltage, not lower
3) form factor, i.e. axial vs radial, physical size if space is limited, and lead spacing.

 

In general, I am not too picky about finding the exact replacement. What I would want to match are:

1) value of capacitance
2) operating voltage. You could even go with higher voltage, not lower
3) form factor, i.e. axial vs radial, physical size if space is limited, and lead spacing.

Thanks, I have those bases covered.

 

It looks like most of the parts listed in this earlier post are still available Parts List with 3 exceptions. Hopefully this list is accurate as I have not verified it yet.

C12 & C15 (same part) are out of stock, is 647-UCY2D121MHD6 a safe alternative?
C10 is out of stock, is 667-EEU-FS1C222L a safe alternative?

I'll assume the author of that list did a good job of matching. Your proposed alternatives look fine to me. I have just one niggling point on the C12/15 part: I've never heard of that brand. I try to stick with known-good manufacturers such as Panasonic and Nichicon if I can. I believe this is the one I used:
https://www.newark.com/panasonic/ee...trolytic-capacitor/dp/39P9899?ost=eeu-ee2e151
(I see that the capacitance and voltage ratings are a little higher, as I noted in post #18 in this thread)

 

It used to be, back when I worked at a service shop, that RUBYCON electrolytics were usually defective. That was in the era when Sony and Superscope both used a lot of them. Quality might have improved a bit since that time.

 

Well I have a partial success story. I've swapped out C8 and that put a stop to the constant beeping and seemingly resumed normal operation. However I have a dual zone cooler and one of the zones will not cool below 65, while the other cools down to 55.

 

Insufficient cooling might be due to an inactive section of the peltier device, or a failed heatsink connection, or possibly a temperature control system calibration error. So additional investigation may lead to a fix. Verifying the voltage to the cooling element would be a start.

 

Insufficient cooling might be due to an inactive section of the peltier device, or a failed heatsink connection, or possibly a temperature control system calibration error. So additional investigation may lead to a fix. Verifying the voltage to the cooling element would be a start.

Since the 2 boards are identical I swapped their positions to see if that made any difference in which chamber was undercooled. It did not, so it seems the issue is not with the board. The green LED is off on both boards as well. IIRC from elsewhere in this thread, that LED comes on when the existing temp is above set temp and indicates cooling is in progress. Perhaps I have a bad temp sensor? I don't have the slightest idea on how to diagnose that however.

 

Indeed, if the problem does not move with the PCB, it would be in either the cooler circuit or the temperature circuit.
A simple diagnostic check would be to measure the resistance of each sensor at a given temperature and see how close the values were. That may not work with semiconductor sensors, though. IN addition, measuring the voltage applied to the 2 Peltier devices may provide a clue as well.

 

Measuring the voltage and current going to the TEC will also give some clues on the health of the TEC.

 

the voltage by itself will tell quite a bit. Measuring the current may be difficult, as it requires breaking the circuit, which is a "big deal", given that the heat-pumping diodes are current operated devices.
Besides that, most of the heat transfer function is by conduction, meaning that the physical integrity of the heat path from the cold area to the hot area is vital. Any air gaps will vastly reduce the heat transfer process.

 

Any tips on exactly where I should measure? All I have is a basic DMM with simple leads (not clips) for testing. If I'd need to break a circuit and put an inline measuring device there instead that would be difficult. I'm not as knowledgeable as most here so not exactly sure what I'm doing. If this is just about measuring a voltage across 2 points on the board I can handle that, but the board isn't labeled well so I'm not sure of exactly where to measure to cover the items that have been mentioned. Worst case I just have a slightly undercooled chamber which at 66 degrees would still be mostly ok for red wines.

If it helps, this post contains a pic of the same board that I have. https://forum.allaboutcircuits.com/...hermoelectric-wine-cooler.176296/post-1595419

 

A measurement of the voltage across the heat transfer (Peltier) diodes can tell a fair amount. Measuring the current would certainly take a much greater effort, and the added resistance of the current measuring connection will probably change the current. But a voltage reading can tell us if the Peltier diode is open or working.
And keep in mind that the heat transfer is by conduction, That means no air gaps at all.

 

A measurement of the voltage across the heat transfer (Peltier) diodes can tell a fair amount. Measuring the current would certainly take a much greater effort, and the added resistance of the current measuring connection will probably change the current. But a voltage reading can tell us if the Peltier diode is open or working.
And keep in mind that the heat transfer is by conduction, That means no air gaps at all.

Thanks, but unfortunately I'm not sure where those diodes are located. I don't think air gaps are the problem but I'll double check that as well.

 

The Peltier diodes are physically between the cold side and the hot side heatsink assemblies.

 

It looks like I have a bad interior cooling fan. I just noticed it wasn't running in one of the zones and there is power to the fan wiring connector. I swapped the location of the two interior fans and the working fan functioned in both location while the bad one didn't work in either.

The fan is Tianxuan model # TX8025l12S. Does anyone have a good lead on where to order an inexpensive like for like replacement?

 

It looks like I have a bad interior cooling fan. I just noticed it wasn't running in one of the zones and there is power to the fan wiring connector. I swapped the location of the two interior fans and the working fan functioned in both location while the bad one didn't work in either.

The fan is Tianxuan model # TX8025l12S. Does anyone have a good lead on where to order an inexpensive like for like replacement?

My cooler had a dead fan as well. You need to match the physical size, so that it fits easily, and read the electrical specs on its label.

This one might be an upgrade
https://www.amazon.com/ARCTIC-Silent-inaudible-Configuration-ACFAN00245A/dp/B08WHMP2CD

 

My cooler had a dead fan as well. You need to match the physical size, so that it fits easily, and read the electrical specs on its label.

This one might be an upgrade
https://www.amazon.com/ARCTIC-Silent-inaudible-Configuration-ACFAN00245A/dp/B08WHMP2CD

Thanks, this one is a 3 pin connector so it won't work for me. The fan I need appears to by 80mm x 80mm x 25mm. My biggest concerns were getting one that's equally quiet, ships relatively quickly, isn't expensive, has the proper current rating (0.08A) and 2 wire connection. I wasn't sure if there was anyplace that might stock some of these. Unfortunately I don't live near a microcenter and digikey/mouser seem to stock higher RPM (louder) fans.

 

Thanks, this one is a 3 pin connector so it won't work for me.

Maybe. The 3rd wire is the tachometer signal which can remain unconnected. The other two are power. So getting the pins lined up is important but not at all difficult.

Or just get a 2-wire:
https://www.amazon.com/GDSTIME-80mm-25mm-Brushless-Cooling/dp/B00N1Y50QQ

 

Maybe. The 3rd wire is the tachometer signal which can remain unconnected. The other two are power. So getting the pins lined up is important but not at all difficult.

Or just get a 2-wire:
https://www.amazon.com/GDSTIME-80mm-25mm-Brushless-Cooling/dp/B00N1Y50QQ

I ended up ordering this one from Digikey.
https://www.digikey.com/en/products/detail/sunon-fans/MF80251V3-1000U-A99/6198724

 

I made the mistake of not noting the fan direction before removal. Do the interior fans (cold side of the TEC) blow air away from the TEC and towards the refrigerator door, or the inverse? I'm fairly confident it blows away from the TEC, just wanted to confirm.