Just setup your soldering station, open the amp up and re-flow every joint that connects to a major component, and any others that aren't shiny. The constant heat cycling causes physical expansion/contraction near transistors and large capacitors, stressing the soldered joints so they get micro-cracks which cause the intermittent troubles you are describing. Alternately 20 years of vibration will crack joints holding heavy components.
A real pro would wash the back of the board with pure alcohol first, lightly scrubbing with a toothbrush (no force on any small/SMD components). Then do the same after you're done soldering. Tip: When you re-flow a joint, add some solder if it looks dull. Iron @380 degrees, and use a magnifying glass if you have to, to be sure you don't leave any solder shorting one pad to another as sometimes they are very close.
All will be good after this, I've little doubt. For a certain fix, you swap the capacitors, but these are all pretty good quality, so I'd only change one that is leaking or showing signs of internal pressure (in extreme situations they can explode like tin cans)
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Originally Posted by 632 Regal
