Vintage Synth Repair

On Sunday 21 October 2007 22:20, synapticdistortion wrote:
> One thing that I've noticed is that there is a hard, tan-colored
> substance at the bottom of several of the caps.  I can't tell if it's
> leakage, or some sort of thermal material that was placed there during
> manufacturing.  The caps in question otherwise look fine (no bulges or
> splitting).

That's a goop that they use to put the caps in and hold them in place until 
they can be soldered,  very common in stuff of japanese manufacture.  But 
there's a gotcha -- as the stuff ages,  it changes,  gets darker,  _and gets 
conductive_!  If it's a light tan in color you should probably be okay, but 
if it's dark brown you might want to scrape it off.  Found that bit of info 
at repairfaq.org...

Power supply troubleshooting is pretty straightforward.  No outputs?  Check 
your power going in.  Make sure you have AC at the input to the transformer. 
Check for AC at each secondary winding coming out.  If that's there,  then 
check for DC on the other side of each rectifier present.  When you don't 
find what you're expecting to find,  then you start digging a little deeper.

-- 
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space,  a critter that can
be killed but can't be tamed.  --Robert A. Heinlein, "The Puppet Masters"
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Information is more dangerous than cannon to a society ruled by lies. --James 
M Dakin