Vintage Synth Repair

This problem can become even more of a problem if the electrolyte manages to
get down into the plated through holes as it can then get into the
intermediate layers where it becomes virtually impossible to repair.  It may
not be realized that these boards are often multi layer, not just simply
with track on both sides of the visible board but may be 4 or even 6 layers
each layer comprising track on both sides.  Most computers these days are
multi layers systems with 6 or more layers.

 

Needless to say if electrolyte gets down into the intermediate layers you
cannot get in there to clean it off.  In the past I've spent several hours
cleaning up a board, replacing dissolved track and putting in new components
only find that the board still fails to work probably due to inter-layer
damage.

 

Regards

Brian G3OYU

 

From: vintagesynthrepair@yahoogroups.com
[mailto:vintagesynthrepair@yahoogroups.com] On Behalf Of Scott Nordlund
Sent: 04 March 2010 2:19 PM
To: vintagesynthrepair@yahoogroups.com
Subject: [vintagesynthrepair] Re: Pay me now or.....

 

  


> Could you please describe (both for me and for all the people in the
future who will be reading this sequence of postings) exactly what kind of
damage that an old memory battery does to vintage synthesizers? Thank you.

Specifically the problem involves rechargeable NiCd batteries. The more
common lithium batteries shouldn't cause any trouble (not that I've ever
seen, anyway). Of course ordinary AA batteries can also leak and ruin your
day, but these aren't usually mounted on circuit boards.

A few things that use these: Korg Polysix, Poly 61 and Trident, Siel DK 600,
DK 700 and Expander, Roland CR-78, Kawai SX210 and SX240, PPG Wave series,
Wersi, as well as lots of other old electronics. Leakage in pinball machines
seems to be particularly insidious, I guess because they can sit in storage
for a couple decades while the battery works its magic.

Over time the (NaOH or KOH?) electrolyte leaks out, possibly encouraged by
the recharging circuit. Component leads corrode, circuit board traces turn
black, solder turns to a powdery gray substance. The damage can spread to a
quite impressive area, though not all of it will need to be repaired. The
solder is especially a pain since it won't melt or allow new solder to
adhere. It can be very difficult to remove without actually drilling out all
the vias and holes. 
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