Vintage Synth Repair

Yep,  they use the P.R.  

Did it to my 3604.  The keys were sticking on that too!!!

Guv


--- In vintagesynthrepair@y..., mtcasino@c... wrote:
> Dave:
> 
> I don't know if the Arp 3604 keyboard uses Pratt-Read Bushing, but 
they worked on my Odyssey just fine.
> 
> Mike Casino
>   ----- Original Message ----- 
>   From: djbrow54 
>   To: vintagesynthrepair@y... 
>   Sent: Saturday, July 27, 2002 11:31 PM
>   Subject: [vintagesynthrepair] Help - ARP 3604 Keyboard
> 
> 
>   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
> 
> 
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