Re: Advice on calibrating
- Hello Florian,
Yes, I was aware of your page on this. And thank you for adding my humble contribution to it. I was about to write you a note about this possibly missing info.
Although since I use a frequency meter, the service manual from Korg was clear enough for me.
I just use A4 and A1, instead of A#4 and A#1. (easier numbers to work with: 440hz, 55hz, 3520hz)
My own procedure is quite simple, and follows a path similar to the Korg manual. And for those of you who would rather use a frequency meter than a tuner, here it is in 8 easy steps (well 32 to be exact):
Transpose switch to NORMAL. (A voltage of exactly +5.250 V must be confirmed at the right side of R8 in the KLM356 CV1 output before continuing).
1-Octave switch to 16'
2-Play A4, adjust vr102 to read 440hz
3-Play A1, adjust vr103 to read 55hz
4-Repeat steps 2 and 3 until values displayed are EXACT.
5-Octave switch to 2'
6-Play A1, adjust vr101 to read 440hz
7-Play A4, adjust vr104 to read 3520hz
8-Repeat steps 6 and 7 until values displayed are EXACT.
Repeat steps 1 to 8 for VCO 2-4 with their corresponding VRs.
Note: you can tolerate a +/- 0.2 hz value fluctuation to account for analog drift.
--- In email@example.com, Florian Anwander <fanwander@...> wrote:
> Hi Alain
> do you know my instructions on this:
> http://fa.utfs.org/diy/korg_monopoly/vco_adjustment.html ?
> > Another extremely critical point, is that you have to FIRST calibrate the voltages on the PSU. Then, calibrate the keyboard CV generation by adjusting the Key Assigner KLM356 to very precise values (a high precision DVM is essential here).
> > Don't start the VCO calibration unless you have confirmed that the assigner is generating EXACTLY 1 volt per octave, as described in the calibrating procedure. Otherwise you'll have a very hard time getting things right.
> Very good point! I'll add it to my instructions
- Hi,Thanks so much for your post, your method is by far the easiest to follow. Last night I successfully calibrated and tuned my new (to me) MP and the pitch is bang on within a few cents right across the octaves...I used an ossicilscope to measure the frequency on A 440 and the relative notes...Next up is the VCF and VCA.... =)thanks again..
- HiI have followed the instructions on the tuning procedure - and was hoping to get a fairly good result from doing the power supply and key assigner calibration. And the perhaps followed by an offset change on VR1-VR4.This was to pehaps not have to deal with removing the whole VCO PCB (KLM-354), as I guess there is no other way if you need to adjust the VR101-VR104, VR201-204.. ... ..and so on.But the offset did not work for all OSC. So I have to remove the whole PCB. Any suggestion on how to do this in a safe (not to damage it) and easy way?RegardsNiklas