Quote:
Originally posted by wbain5280
This is a good writeup. You have shown that by doing a little work yourself, a lot of money can be saved. It also shows the manufacturers are making these devices on the cheap. Not enough solder is used and breaks after a few years due to vibration.
One question though, why use flux paste? Solder comes with flux in the middle. Heat up the solder, the internal flux does the same thing.
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The problem is actually a cold solder joint here and there, not just too little solder (I'm sure they're wave soldered anyway, even back then.) Mfg speed would be the culprit I suspect. Also, rosin core solder is great for clean boards, but with old joints, some oxidation, oil, crap, etc., dousing with flux helps get a good joint despite the odds against.
Tracked down a cold solder/vibration problem that caused an intermittant failure in a radar unit on a military transport back in the early '80's (anyone else lose a few fillings on a 130?)
Everything was to mil spec, checked joints, signed off, everything, but the vibration just took its toll, despite an originally perfect joint. Things can happen even with perfect mfg (especially in a diesel, known for it's "smooth" running!)