Re: Thermo electric pcb power supply

Eureka, got it to work at lunch time today.
I managed swap out the remaining electrolytics, 1, 4.7, 22 uF caps. There were about 6 small caps to replace. I replaced 4 of them and it worked. I noticed that the caps were between 1/2 to 1/10 the rated capacitance. Just for peace of mind I also changed two more caps which I think were used for the snubber for the switching transistors.

Doing an aging test tonight.

Thanks again. Funny that it turned out to be bad caps.

Peter

Re: Thermo electric pcb power supply

Budm:

I did a quick visual.
Looked pretty normal, but I did notice one odd trait. I had to push the probes pretty hard to get continuity ? However, i did not see any evidence of any comformal coating ? Wonder why ?

Peter

Re: Thermo electric pcb power supply

Tom:
Changed the input bulk caps( 120uF 200V) and the output filter cap( 220uf 16V) of the+12V line and there was no change in the operation. I wonder what to do next ?

Should have asked if anyone ever managed to find a schematic of this ps ?
p

Re: Thermo electric pcb power supply

Update: disconnected the peltier, then plug in the AC power, fans run. While still plugged in, I re-connect the peltier to the ps, and it continues to operate fine. Left it for 2 hours Works great. I wonder what causes the system to
output basically 0 volts to the peltier if started up with the peltier connected ? OCP ? I wonder if the bulk caps are degraded so they can's support the inrush current requirements ?
Peter

Re: Thermo electric pcb power supply

Hi:

just joined today. I have a problem.
The interior LED turns on, but hte cooler and fans are dead.
checked the sw tr's, diodes and serires resistors and all seem fine.
Does anyone have any hints ?
Or better yet a schematic of this supply ?
Peter