Vintage Synth Explorer Forums

I am trying to calibrate a MS404 but I am having a problem with the P17 "VCO Scale" cermet trimmer, it seems that it is not working at all. I have only tried turning it a few turns and I get no response.
The specs are "500 25-turn cermet trimmer 9.5X9.5mm". what does 500 stands for ? ohms?
Can anybody recommend me a substitute ?

Also can anybody translate this ?:

3. Die VCO-Scale mit P17 zunächst grob einjustieren, so daß beim Spiel auf dem angeschlossenen MIDI-Keyboard Oktavsprünge am MS-404 richtig wiedergegeben werden (Oktavsprünge am Keyboard müssen eine Frequenzverdopplung des VCOs bewirken).

Here is the german service manual:
http://www.doepfer.de/ms404_sm.htm
Thanks

Translation (more of a paraphrase):

"Adjust the VCO-scale with P17 roughly first, so that it plays correct octaves over a midi keyboard (playing octaves on the keyboard must double the VCO's frequency)."

Many thanks , I really appreciate it

It seems that the P17 needed lots of turns to start working ; now I understand why it is called a 25 turn trimmer

I ll post the calibrating procedure later in this thread for any future reference.