Help: Minimoog model D - no sound

[galino]

Hello to all

I have a model D (serial T2336E) which is not producing any audio. I turned it on last week (the first time in a little while, stupidly enough) and it seemed alright. Then a day later I started it up again and there was nothing. The A-440 works as usual when switched on. I usually control this synth via external CV/gate but even that is not working so I doubt if it's the keyboard.

Has anyone come across similar problems or have any idea what it could be? I had problems with the pitch (wandering) it not long after purchasing it a few years ago but was able to get it fixed by a technician. Now I'm not confident to open it myself and sending it back to a tech is going to become rather costly and time consuming.

Any advice is appreciated

[thealien666]

It is most probably a bad electrical contact somewhere. I would suspect at the printed circuit board connectors. 98% of Minimoog D problems come from poor, or bad electrical contacts (on the keyboard Cinch-Jones connector, the Mod Wheel Cinch-Jones connector, the PCB boards connectors, the keyboard Buss Bars and coil contact springs, inside toggle switches and "sealed" Allen-Bradley potentiometers, and finally trimpots adjustments on some of the boards). It's especially true if stored for a long time (worse in a damp cellar or humid climate). It is very rarely due to a failed electronic component (although still possible).

If your feel like it, and with the power cord disconnected, you can safely open the back of the panel, and remove the screws that are holding the boards in place and pull them out of their connectors at the bottom, one by one. It will require a little effort, as these are held rather tightly. Once that's done, proceed to carefully clean the edge contacts with isopropyl alcohol (or contact cleaner). Once that's done, simply reconnect each board, and put back the screws holding each of them in place on top. And power the synth back up. If everything seems fine, put the back cover back on.

Or if you don't feel comfortable doing all that yourself, you can always send it to a qualified tech who will most probably do the same for a fee.

Good luck.

[galino]

Thanks a lot thealien666

This is weird, but I turned it on just now and it actually works fine (seemingly). Though I don't doubt that this same problem could arise in the future so I will keep your advice in mind. Yes it is a humid and hot climate and I don't turn it on every single day (which I've been told I really should).

A bit scared to turn it off now

Thanks

[thealien666]

You're welcome. Glad it came back to life on its own.
Keep fingers crossed... (well actually not because you want to play it )
Anyway, it's definitely a sure sign of intermittent contacts somewhere inside. If it's goes dead again, you'll have an idea of what you can try.
BTW, I'm intrigued by your serial number starting and ending with a letter. The T probably stands for Trumansburg (where Minis were first made), but the E at the end has me stumped.

Cheers !

[galino]

To my dismay I turned it on this morning and there is again no sound.

When I've got the time and the courage I will follow your advice and open it up to clean the edge-contacts. Wish me luck!

I'm not sure about the serial number, it may have been added at a later date. The metal casing has also been painted red by one of the previous owners. This synth has evidently had a hard life.

Many thanks.

[thealien666]

Sad to read that it died again.

A little patience and some TLC should revive it once again.

Best of luck to you.

[galino]

Hello again,

I opened it up recently and cleaned as many of the circuits as I could. Unfortunately there is still no sound. When I opened it up it looked quite dirty and dusty inside. I am just wondering, could it be a problem with the wires under the keyboard? or is it possible I did not clean it properly?

Many thanks