[sdiy] When good caps go bad!

Oakley Sound oakleylist at btinternet.com
Wed Jun 11 09:52:11 CEST 2014

Just had an RS-505 in. Nearly half of the electrolytic caps had green 
fur around one of their leads. The smoothing caps had dried gunge all 
around the end of the case. This is pretty typical for a 1970s Roland. 
My own RS-202 needed every single ruddy electrolytic replaced - all had 
green fur and/or brown spots underneath them. Those that I tested were 
electrically leaky too.

Korg stuff from the 1970s often uses 16V caps on a 15V rail. Most are 
well past their date and many will have leaked or will have gone open 
circuit. On PS-3X00 units leaky capacitors have a habit of eating their 
way through the topside copper traces.

Moog stuff seems better, but those black cylindrical Kemet caps often go 
short or open. Moog did use for a time a type of 'tropical fish' cap, 
like the Mullard C280 but not quite. They have a tendency to literally 
fall apart.

Had a few leaky memory back up supercaps too.



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