[sdiy] OB-8

[Magnus Danielson]

From: bill bigrig <billbigrig at yahoo.com>
Subject: [sdiy] OB-8
Date: Fri, 5 Jan 2007 21:33:58 -0800 (PST)
Message-ID: <20070106053358.73235.qmail at web32713.mail.mud.yahoo.com>

> Howdy,
> 
>  Maybe you guys can help me out. My freind recently
> bought an OB-8, and one of the voices is "hinky". It
> sounds like it's being pitch moulated with a square
> wave. Where would a guy star to look for the
> cause?Thanx
> Rig

I'd start to suspect the S/H chips. You do want to establish which voice it is.
This you do quite easilly by opening up the hatch and as you press a key you
will loop through the voices and along it will a LED on each voice light up.
Quite amuzing.

You do want to look in the service manual, but fortunatly I've put it online:
http://rubidium.dyndns.org/~magnus/synths/companiers/oberheim/

page 22-24 is the voice-board, so be sure to check those. There is also very
good hints about how to open the damn thing.

It might be the scanner frequency creeping through due to a bad S/H chip.
I hardly think it is the LFO since the OB-8 has the LFO done in software, so
that would mean leaking in the code and well... no. :)

Cheers,
Magnus