I went through this when I rebuilt my trainwreck Mono/Poly. The offset is obviously only a part of the overall procedure but it was a case of adjusting to get as close to zero as possible but measured at pins 1,3,5&7 on connector 39. The whole procedure I used is in the forum 'Files' section under 'Misc Files' - 'Poly.pdf'.
--- In firstname.lastname@example.org, "ohmstudiste" <ohmstudist@...> wrote:
> I got a mp4 that I recently recalibrated and is working very nicely. Tuning/scaling is very good.
> I checked all the voltage and got good and steady readings on the power supply and keyboard CV voltages.
> But when it comes to measure the VCO offset in the klm398 I don't get the 0.000v +/- 1mv. Instead I read voltages bretween 1v and 3v and they change if I play notes on the keyboard. The voltages are responsive to the different VR on the board but I can't make them 0.000v.
> So question are:
> - Am I reading the good points ? i connected to J12 and to the respective 4 colour wires mentionned in the manual (and corrected here for new version)
> - Is there a key to press while reading ?
> - Is it dangerous for the OSC to have these readings ? As i mentionned my mp4 is really nice tuned and scaled, for every oscillators.