Vintage Synth Repair

It could well be a combination of dirty contacts and misalignment of the
contacts. The ARP keyboard uses multiple contacts per key for CV & gates.
The contacts need to connect & disconnect at different times to ensure that
the sample/hold (memory) circuitry works correctly and latches the correct
voltage. The service manual describes the process and is readily available
on the web.

Search the archives for contact cleaning procedures - you need to avoid
removing the plating from the contact wires (assuming that there is still
some left!)

If cleaning/adjustment doesn't work then it could well be the S/H circuit
itself. Is the pitch change random or does it lower each time you press the
same key?

Good Luck!

mw

-----Original Message-----
From: vintagesynthrepair@yahoogroups.com
[mailto:vintagesynthrepair@yahoogroups.com] On Behalf Of arp2600fan
Sent: Friday, April 21, 2006 11:12 PM
To: vintagesynthrepair@yahoogroups.com
Subject: [vintagesynthrepair] Re: Arp 3620 keyboard NOT Work

--- In vintagesynthrepair@yahoogroups.com, "synthiaks2004"
<synthiaks2004@...> 
wrote:
>
> I just got a Arp 2600 MK III with 3620 Keyboard. But the keyboard doesn't
work. It can 
> sound but every time the key will get different pitch even I only press
the same key 
again 
> and again. Do you know what problem was that?
>

My first guess is that the contacts need to be cleaned, but it could be more
than that.