Hi all,
As the header suggests I have a late serial Model D problem that through extensive searching no else seems to have reported. What happens is, on Oscillator 3, when any of the 3 square waveforms are selected the entire synthesizer (all oscillators) is transposed up or down by a semitone (each of the 3 waveforms transposes it by one or two semitones) furthermore though I have cleaned both of the wheel connectors and all edge connectors the modulation wheel has no effect.
Regarding the modulation wheel I noticed the below thread which reported a similar problem (only minute pitch bend on modulation wheel) however my mini only has two wires connected unlike that poster’s photo of three. The pitch wheel works perfectly after polishing the connector incidentally.
https://www.gearslutz.com/board/electronic-music-instruments-electronic-music-production/921778-minimoog-model-d-modulation-depth.html
Finally – though I don’t feel this has any bearing, the minimoog has the optikey synthfool upgrade installed.
thanks in advice for any advice on where to zero in this problem!
Cheers
Hello and welcome pushwithlegs !
To be clear, you should not confuse the Mod Wheel with the Pitch Bend Wheel. The Mod wheel has only two wires going to it. The Pitch Bend Wheel has three.
If the Pitch Bend Wheel only imparts a minute change in pitch, check for dirty contact on the Molex connector (black Bakelite one with many legs), or possibly one (or more) broken wire on it.
The fact that your Mini has the Opto-Key installed eliminates any keyboard contact problems.
As for the initial problem of the overall pitch changing when selecting square waves on Osc 3, make sure that the Oscillator Modulation switch is OFF (in the Oscillator Bank section), and that the Mod Wheel (the one on the right) is completely down.
If, when the Mod Wheel is down and the Oscillator Modulation switch is turned on, the pitch changes when selecting square waves on OSC 3, then there might be a broken wire (or loose connection) on the Mod Wheel potentiometer, allowing full modulation of the pitch of OSC 1 and 2 by OSC 3.
Alain.
Hey.
As I say all the molex and edge connectors have been cleaned and the pitch wheel works perfectly.
The mod wheel on the other hand does nothing (except as in the gearslutz link) alter the pitch by less a semitone when fully engaged regardless of settings.
There are no missing or damaged wires in the wheel section which leads me to believe both faults are tied to oscillator 3 or the modulation board.
As for the waveform transpose glitch it occurs with every switch in either position. Nothing can make it not occur. Even if I turn off oscillator 3 choosing any of the square waveforms cause the transposing to occur on osc 1 & 2.
Cheers
Okay an update. Problem solved!
In opening wheel panel to take a photograph of the inside I plugged the molex connector in and out a dozen times (this is after having meticulously cleaned it already) and lo and behold the mod wheel is working as it should and the transpose waveform problem has disappeared.
Moral of the story is that those molex connectors need to be either spotlessly polished or replaced with more reliable connectors or else weird faults still remain.
Does the pitch alteration of OSC 1&2 still occurs when the “Oscillator Modulation” switch is in the OFF position ?