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Wow, JamesO, great advice. I had forgotten about cold solder joints. Yes, I've found a few in my time as well. As you suggest, I'll just go over it and retouch any joint that looks at all suspicious.
I haven't moved it lately, but I have had a lot of heat fluctuations. It got really hot in here last summer (had a hard disk fail) and then really cool in the winter. I can't afford to run A/C all the time; I'd have a $1000/mo electric bill.
The other thing to mention is that there is a power-dip event that happens every morning around (though not exactly at) the same time. I believe it's one of the car dealers near me starting up some huge piece of equipment. All the UPS's in my place fire off (I have a few other BackUPS on workstations in other rooms). My poor SU1400RMXL was "tested" every single day for the last year, sometimes twice a day. That had to have some stress on the system.
I've had PG&E (our local corrupt power company -- remember the FAKE CA energy crisis a few years ago?) out here a few times to document the power events. They left recording voltmeters on the line but claim to have never found anything. Sheesh, the first one they put on had a resolution of about 10 seconds! Then they came back and said they were putting on a "really high resolution" recording unit. It turned out to have a resolution of 100 ms! Many power events have durations in the microseconds. So they never found anything, and the culprit is still conducting their "evil" practices.
As for fuses -- I already found a couple of secret, internal "they never blow" fuses, soldered to the main board of all things. Unfortunately, they weren't the problem; they test out good.
I'll let you know what happens with the cold-solder-joint rework. It'll probably take me a few days -- it's going to be a big job to completely extract the PCB. It's got a ton of connectors and big wires bolted to big heat sink fans; I'm going to have to be very careful about extraction and documentation of identical connectors.
Thanks again.
- The Inspector
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