Vintage Synth Repair

You're certainly off to an excellent start, you have schematics, such as they are, and a good oscillator to do direct comparisons with. The tool I've found most helpful is an oscilloscope. If you don't have one already, you can always get a used one really cheap.  I recommend starting somewhere where it is working (maybe the signal coming off the keyboard for example ), then tracing it to where one of the oscillators begins to  do something different than the other. That's where it is failing. What it all boils dow n to is that s ooner or later, somebody is going to have to do all  the troubleshooting right there at the instrument . Since I am separated by the internet , I can only make guesses and vague generalizations.
----- Original Message -----
From: salsole@...
To: vintagesynthrepair@yahoogroups.com
Sent: Monday, December 9, 2013 9:11:52 AM
Subject: [vintagesynthrepair] ARP Solus OSC1 tracking issue. ..

 




Hello all... I don't know whether the last message I sent made it through or not... Anyhow. I am working on an ARP Solus that had a dead VCO1. I replaced the tempco resistors, (r60 and r98) and it fires up and sounds great. Now the issue I am having is that VCO1 tracks in reverse, and badly at that. VCO2 is tracking perfectly. The service manual and schematics available are pretty poor in quality and somewhat topical in nature. Anyone have any suggestions about where to look? Thanks much