[Coco] CCR-81 Emergency surgery

[Joe Grubbs]

Today my CCR-81 mysteriously stopped working. It was completely unresponsive almost as though the power supply was completely dead.

I've had it since day one, and I'm a bit attached to it so I wanted to fix it if possible. I disassembled it and looked it over. I tested a few things, then quickly ran out of talent (and diagnostic tools). I took it to one of my best friends who happens to be an electrical engineer. He was also a bit perplexed by the failure. Everything seemed in order--no shorted or open diodes, no cold solder joints, etc. 

However after some "reverse" logic, we found that the power supply was being completely shorted out any time the unit was activated. Idling it was fine, but pressing RW, FF, Play, Record, etc seemed to short the supply. To make a long story short, it turned out to be one of the two 2200uF power supply caps was shorted. Yes, a shorted electrolytic. He's seen that before a number of times but this was a first for me. I've seen film caps short, but not an electrolytic.

We replaced the caps and voila! The CCR-81 lives on!

-Joe