I recently got my hands on a Moog Liberation in a pretty bad cosmetic shape, and since the closest store that services and repair moogs are really far away and I have some basic knowledge of electronics I thought id give it a try to get it working before paying expensive for service. The external unit lights up and so does the keyboard. Meaning, the right lamp lights up on each key being pushed down except the lowest key, and respons to the trigger and filter rates. The left lamp only lights up if I push really hard on the Glide-slider, probably a faulty contact somewhere. But there is no sound whatsoever comming out of the moog. Not even any crackles or noise from moving sliders around, only some cracks when pushing keys on the polysection (with or without poly turned on) after the moog had warmed up for about 30 mins.
No replys. Anyway, I got it working. Was a problem with the audio output, the volume knob that was broken and set to 0 and on both ends of the instrument cable. Everything seems fine except for the pulsewave on oscilator 1 that only gives a click and no sound. Any clues?
1st, it isn’t that many of us who could help don’t want to.
It’s that we don’t want to cause further harm to the instrument or you.
It’s very difficult to ascertain what level of technical ability you have and thus, difficult to provide advice.
If you have and can read the schematics, it would help.
If you need them, ask me and I’ll point you to where they can be downloaded or will send them directly to you.
Some questions: Does the ring modulator work?
Do the oscillators sync when the sync switch is turned on?
Does VCO 1 otherwise work (other waveforms ok?)
Does the polyphonic section work?
Unfortunately, you may have to trace the problem and this can require some test equipment and ability to follow schematics.
It could be a bad slider or switch or it could be a chip, transistor, solder connection or connector.
I always suspect mechanical parts first (connectors, switches, PCB, etc) over ICs.
This is the opposite philosophy often adopted by beginning techs.
One should locate the actual problem, not just swap out chips hoping they’ll find a bad one.
If I was to suspect a bad IC, I’d guess it would be U7, an LM393.
But again, it could be any number of other reasons instead.
Where are you located? Perhaps I can suggest someone who can help.
I’m in California, fwiw.
I have the original schematics, found them in a plastic bag glued to the inside of the external interface, looks like they have never been touched!
The Ringmodulator works fine, the oscilators sync up fine, the two other waveforms on the VCO 1 works fine and the polysection works fine as long as the force switch is turned on, dont know if thats normal or not.
I am currently ex-pat in southern France, hence the lack of known (to me) places to get a moog repaired.
I have a moog liberation but i dont have no chord or power supply box/external interface. If I had schematics or more information i could build one. Any help would be greatly appreciated.