Vintage Synth Repair

--- In vintagesynthrepair@yahoogroups.com, "Scott Nordlund"
<gsn10@...> wrote:
>
> >I have recently purchased a defective Siel DK-600, hoping that it
> >might be an easy fixer-upper. Now.. what it does when I turn it on
> >is.. almost all leds are on, the number display in the "program
> >select" area is stuck at 00 no matter what you press and none of the
> >other selector buttons seem to work either. Also the led by the
> >"enter" button keeps blinking. So.. from what I told you what do you
> >think might be wrong? The battery? It doesn't seem to be just a loose
> >cable since all areas of the synth seem to be affected. Any hints and
> >suggestions are highly welcome!
> 
> Ah, I've got one of these.  Broken of course, I think most of them
are at 
> this point.  Take the screws out of the bottom, open it up, and lift
up the 
> keyboard (it's hinged).  You will most likely find that the NiCd
battery has 
> leaked electrolyte and corroded some stuff on the CPU board.  You'll
want to 
> remove the battery and clean it up before it gets worse.  On mine the 
> battery leaked and disabled the button scanning circuits.. so it
turns on 
> and makes sound but none of the buttons work.  Until I fix it, I'm
stuck 
> with a bad-sounding single oscillator saw wave patch.
> 
> Another thing that can go wrong (also happened to mine) is that the
pitch 
> bend potentiometer can short out and blow a fuse.  It's connected to
the 
> power supply rails, but it's some kind of funky center-tapped 4
terminal 
> pot.  I don't remember the exact configuration, but basically when
it wears 
> out it will short to ground and blow a fuse.
>





Ok.. I have just opened it up. I see the battery and it looks like
there's some kind of corrosion or brown stuff around the solder points
 on the board but can't really see much, I'll have to take it
completely out and put some more light in here. How do you clean that?
What kind of solution would I have to use? I am kind of hesistant
because I'm afraid I'm gonna destroy some of the traces on the board.
By the way my synth does not make a sound at all, it just lights up.
About the "exploding" mod poti... how can I work around that? What did
it to your synth when it happened? Is there a way to ground the pot
elsewhwere other than over the power supply?