Re: Help me fix my latest IC7000 failure


Dan Smith - KK7DS <dsmith@...>
 

I'd go with the first one. I've heard of it, but I don't remember seeing one. It may be that I saw one and forgot about it, although we tend to remember the weird things and not the everyday.
Okay, well, I'm definitely going with "it seems fixed now, regardless" :)

It's possible for chip resistors to be manufactured shorted, but I don't know how they grow shorts and go bad. It may be that the circuit board can grow shorts because certain solders can grow whiskers or dendrites that short out parts. That depends on time, temperature, humidity, and the type of solder. That was more common in the early days of lead-free solders, which was around '06 to '08 (very approximately). Coincidentally that's around the time the 7000 was in production.
Thanks for the fascinating summary of the consequences of lead-free solders (a problem I didn't realize existed) and the dangers of over-regulation (a problem I *did* realize existed). Based on that, I suppose maybe just the act of removing it and cleaning the pads was the fix. When I tested it on the bench, I got one reading on it, then went to reposition with the tweezers which is when it left for orbit. I suppose it's possible that I got a bad read on it the first time with my comparatively large meter probes, or that it had become bridged on the backside from the extra solder I added at removal. I feel fairly confident in the testing I did whilst it was secured on the board though.

--Dan

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