[sdiy] strange PCB faults, was:OTA question

Oakley Sound oakleylist at btinternet.com
Sat Sep 18 09:19:11 CEST 2010


Leaking electrolytic capacitors is a serious problem for all sorts of 
older gear. Korg PS series suffer heavily from leaking electrolytics. 
The worse being the 16V rated caps on a 15V supply line which inevitably 
leads to problems. The stuff leaks out the bottom and corrodes the upper 
traces on non solder masked boards. So much so it'll eat right through 
them breaking the circuit or worse creating some sort of weird 
semiconducting trace making unusual fault conditions.

A lot of the tolex Rolands like the System 100, RS-202 etc also have the 
same problem. The usual fault is a small brown spot directly underneath 
the cap and quite often a blue furry leg. Worse ones will again corrode 
traces but most Roland's have single sided boards so are spared the Korg 
problem of dodgy traces.

Into the 21st Century and the Humax PVR-9200T video recorder has a major 
problem with losing track of the time when in standby. The reason - a 
leaky cap contaminating the nearby crystal that drives the RTC. Cleaning 
the board and replacing the cap fixes the problem.

Tony

www.oakleysound.com



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