Vintage Synth Repair

Dave,

As far as the keys sticking,  You should really check out this 
website:

http://pw1.netcom.com/~arcsound/

They sell the rubber bushings that fit inside the keys to stop them 
from sticking and put your keyboard action back to factory quality.  
I've done several of my keyboards and they are GREAT!!!  

Argghh!!! Don't use sandpaper on the bus-bars!!! They'll probably 
work for a while (maybe) & then get oxidised and then you are royally 
screwed!!!  I used the Radio Shack Component Cleaner ($10) and it 
seemed to do the trick.

Sorry, don't have the schematic for the KB, but there are a few 
places including the guy that seems to spend his life selling it on 
eBay!!!

Guv

--- In vintagesynthrepair@y..., "djbrow54" <davebr@e...> wrote:
> I'm trying to restore an Arp 3604 keyboard.  Several questions.
> 
> First, the keys stick in the upright position until the first time
> you depress them.  Then they are fine for about 6 hours at which
> point they are stuck again.  I've removed them all and cleaned and
> regreased them.  Any clues as to what's happening?
> 
> Any good ways of cleaning the bus bars.  I've gone over them with
> alcohol but nothing came off.  They're pretty bad.  I was thinking 
of
> some 600 grit sandpaper and slightly burnishing them.
> 
> My real issue is the CV output.  It's fine up until the input to the
> potted module on the circuit board.  It's a Dynamic Measurements 
Corp
> 148-130 module.  It's pulling the CV negative.  I've removed the
> module and am running the CV straight from the input.  The keyboard
> divider chain is working fine except there is no hold function for
> the CV.  Funny, there is no gate input to this module so I don't 
know
> how it's supposed to know when to hold the voltage.
> 
> Does anyone have schematics for this keyboard or any information on
> the Dynamic Measurements Corp module?  It's got a date code of '74 
on
> the bottom.  I'm trying to unpot it but it's not going very well.
> 
> Thanks. - Dave