This is a platform for User Generated Content. G/O Media assumes no liability for content posted by Kinja users to this platform.

CCRM Component Testing

Illustration for article titled CCRM Component Testing

I found a bad resistor! And that’s not all...

Fist of all, thanks everyone for the responses yesterday. I’m familiar with some electrical stuff, but a noob when it comes to fine electronics. I really appreciate your input.

Advertisement

Since this CCRM doesn’t have a traditional coil-type relay for the AC circuit, I started poking the other components on the board with my multimeter. One of the first resistors I tested (R9) came up bad, giving me a fussy reading of somewhere around half of its stated resistance.

Advertisement

But before getting too excited, I continued testing, and soon found another bad resistor (R11). And a bad diode (D4).

Illustration for article titled CCRM Component Testing
Advertisement

Since I was doing a round of individual component tests, I went ahead and started trying the relays one more time, just for kicks. Surprisingly, *pop* one let the smoke out! I have no idea why. All four of them were good just the other day. Alas, the low-speed fan relay now has zero resistance across its coil. Well, that sucks. I wonder if one of my test probes slipped earlier. Maybe I errantly discharged a capacitor or something.

I can see now why remanufactured modules are so expensive. Between the diagnosis, labor, and testing involved, a hundred bucks doesn’t sound so bad after all. But I like learning, and am not quite ready to give up on this board yet.

Advertisement

Speaking of learning, I hear that capacitors can’t be tested in-circuit. And I’m still unclear as to how to perform a complete test of a transistor, but a preliminary diode check between Base and Emitter terminals is showing 3 of them (Q4, Q5, Q6) to be bad.

Illustration for article titled CCRM Component Testing
Advertisement

The mosfet on the side, which appears to be an important part of the AC “solid state” relay circuit, also failed a diode check between the B and E terminals.

So it looks like this board will need two 100kΩ resistors, one relay, one diode, three transistors, a mosfet, and maybe (?) some capacitors. Is it worth it? Should I just trade it in (core) and get a remanufactured unit?

Advertisement
Illustration for article titled CCRM Component Testing

BTW, I’m having a hard time getting good close-up pics, but I stumbled across this TCCoA thread, which contains excellent photos of a board identical to mine. Check it out for a better view of what I’m looking at.

Share This Story

Get our newsletter