Haier Thermoelectric Cooler - Power Supply Output Anomaly

[bobbyskillz]

Greetings!

I have a Haier thermoelectric cooler that will not cool. The fans may twitch or come on at a lower speed, but the peltier cooling module will cool.

I read this thread, but I still haven't been able to find the cause of the problem.

The power output seems to vary greatly for no apparent reason. I'm getting everywhere from 2-17VDC from the output terminals. When I start to draw current with a load, regardless of whether it's a fan or the peltier module, the voltage drops drastically. When this happens, I hear what sounds like dripping water (or arcing) coming from the area with the two largest capacitors.

I went over everything several times with a lighted magnifier, but don't see any signs of burnt or damaged components.

Is there something I may have overlooked that may cause the output voltage to vary so much? It varies even after I remove the load.



I've replaced all the electrolytic capacitors. I also tried swapping out the 13005-2 rectifiers. I swapped out the LM358P Op Amp, too.

For some of this soldering, I was left with only a cheap 30w soldering iron from Radio Shack. Please excuse some of the butchering that may be apparent in the solder-side pictures.

[digge]

Re: Haier Thermoelectric Cooler - Power Supply Output Anomaly

That board looks very similar to one I've worked on in the past (some cheap-ass Chinese whine cooler in my case). I think i swapped all of the caps, and if memory serves me right i also swapped some of the "3 legged components" as well, the two that sits in a pair. Cant see what components they are from your pics though.

Ofc you might have a different problem with that board then i had though

[bobbyskillz]

Re: Haier Thermoelectric Cooler - Power Supply Output Anomaly

That board looks very similar to one I've worked on in the past (some cheap-ass Chinese whine cooler in my case). I think i swapped all of the caps, and if memory serves me right i also swapped some of the "3 legged components" as well, the two that sits in a pair. Cant see what components they are from your pics though.

If you mean the two that are side-by-side on the aluminum heatsinks, they're 13005-2 (TO-220) transistors. I only had one of these in my parts chest, so I first soldered it in place of one, had the same results, then put it in place of the other.

The strange thing I noticed about these transistors is that one of them has a plastic insulating washer between the screw and the heatsink. It also has a rubber pad behind it. I suppose it's there to insulate it. The other one has neither the plastic washer nor the rubber pad.

[digge]

Re: Haier Thermoelectric Cooler - Power Supply Output Anomaly

Those are the ones i meant. Im not an electronics engineer though so the package names and stuff is not my strong side Did the swapping do any difference at all? Like did it sound in another way or anything?

If i remember tomorrow ill look for the order confirmation on the parts i ordered for it.

[bobbyskillz]

Re: Haier Thermoelectric Cooler - Power Supply Output Anomaly

Those are the ones i meant. Im not an electronics engineer though so the package names and stuff is not my strong side Did the swapping do any difference at all? Like did it sound in another way or anything?

If i remember tomorrow ill look for the order confirmation on the parts i ordered for it.

If it had any impact on it, I think it was a detrimental one. If I recall correctly, the voltage was even lower at the output.

I sincerely appreciate your input on this!

[bobbyskillz]

Re: Haier Thermoelectric Cooler - Power Supply Output Anomaly

I've gone ahead and ordered a new board. I blew up those two transistors and don't feel like waiting for replacements. I'll have the new board tomorrow. I'll keep the old one around, in case I decide to order those transistors and retry a repair.

Thanks for the help!