Problems with minimoog mod wheel

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StuBrew
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Location: Eastleigh, UK

Problems with minimoog mod wheel

Post by StuBrew » Wed Jul 20, 2011 2:39 am

Hi Guys,

Picked up my Model D last night and everything sounds great apart from Im have a few problems with the mod wheel. Instead of a nice vibrato it weirdly seems to just increase the pitch as you raise it, open up the filter and add some cross talk from the noise section.
It could be just user error and to be honest its not the end of the world, Ive been very lucky with all the other vintage stuff Ive bought so far and Im sure its easily fixed but if you have any ideas that would be much appreciated!

Goom
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Re: Problems with minimoog mod wheel

Post by Goom » Thu Jul 21, 2011 10:13 pm

Hmmm - if you haven't already done this, try these settings:

Osc 3's octave switch to the "Lo" range
Osc 3 Control switch to off
Filter Mod switch to off
Osc Mod switch to on
Adjust Modulation Mix control to Osc 3

Play a note, turn up the mod wheel, and adjust Osc 3 fine tune pot as desired.

CliftonSantiago
Posts: 2
Joined: Thu Nov 17, 2011 10:45 am

Re: Problems with minimoog mod wheel

Post by CliftonSantiago » Thu Nov 17, 2011 10:54 am

Goom wrote:Hmmm - if you haven't already done this, try these settings:

Osc 3's octave switch to the "Lo" range
Osc 3 Control switch to off
Filter Mod switch to off
Osc Mod switch to on
Adjust Modulation Mix control to Osc 3

Play a note, turn up the mod wheel, and adjust Osc 3 fine tune pot as desired.
Have been having the exact same problem, mod wheel only changes the pitch slightly. Tried what you suggested here but still the same issue. Might anyone know what could be causing the problem? (apart from user error, which is quite likely). The rest of my minimoog works almost perfect!

torinkrell
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Re: Problems with minimoog mod wheel

Post by torinkrell » Fri Nov 18, 2011 10:00 am

Assuming that your Minimoog Model D is indeed in great working condition (otherwise), and that you are an experienced analog synth musician, the issue can possibly be easily resolved. My Minimoog D had the same issue which is that the Molex connector that connects the mod wheel assembly wires (and therefore voltage control routing) to the rest of the synth is probably corroded and is not allowing all the control voltages through. The laypersons solution (mine) is to remove the wheel assembly and locate the molex connector which is a cube like connector with wires on each end. After freeing it where it is secured gently but firmly pull the two halves a bit apart and back together a few times. That will work through the corrosion and may restore function. Do this in sets of two or three and then try the mod wheel. This may be enough for a quick fix and some piece of mind, however it would be better to clean out the corrosion inside this connector or even better bypass it and solder the wires individually instead. I however always try the least invasive method first when I do simple repairs on my analog gear. Congratulations on your purchase! Where did you find your Minimoog Model D?
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CliftonSantiago
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Re: Problems with minimoog mod wheel

Post by CliftonSantiago » Tue Nov 22, 2011 3:07 am

torinkrell wrote:Assuming that your Minimoog Model D is indeed in great working condition (otherwise), and that you are an experienced analog synth musician, the issue can possibly be easily resolved. My Minimoog D had the same issue which is that the Molex connector that connects the mod wheel assembly wires (and therefore voltage control routing) to the rest of the synth is probably corroded and is not allowing all the control voltages through. The laypersons solution (mine) is to remove the wheel assembly and locate the molex connector which is a cube like connector with wires on each end. After freeing it where it is secured gently but firmly pull the two halves a bit apart and back together a few times. That will work through the corrosion and may restore function. Do this in sets of two or three and then try the mod wheel. This may be enough for a quick fix and some piece of mind, however it would be better to clean out the corrosion inside this connector or even better bypass it and solder the wires individually instead. I however always try the least invasive method first when I do simple repairs on my analog gear. Congratulations on your purchase! Where did you find your Minimoog Model D?
Being a layperson myself that does sound a bit daunting, but I'm willing to give it a try. Any good guides you could point me to on how to open up the Mini to do what you mentioned? I did a bit of soldering in DesTech in high school, maybe I can vaguely remember how to do it. Thanks for the understandable answer!

Just bought it a few weeks ago from a guy who selling his locally, it was in good nick so I leapt at the chance. Funny thing was the mod worked perfectly at first, must have gone out a few days after I bought it.

torinkrell
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Re: Problems with minimoog mod wheel

Post by torinkrell » Tue Nov 22, 2011 12:51 pm

Its actually very easy to remove the mod wheel assembly from the Minimoog Model D. For the simplest attempt at this repair you don't even need to detach the connecting wires. If you unscrew the two frontmost screws of the mod assembly the whole thing can be gently pulled out. Then unscrew the Molex connector from the side wall and pull its two halves a half inch apart and push it back together a few times as described above. You may initially need to gently pry it apart. All this is assuming that your VCO 3 is working correctly so you may wish to put VCO 3 into audio mode to see if it is functioning first.

Beyond this it would be best to get advice from one of the real techs on this form after looking to see if possibly this topic is covered in the archives here.
Best of luck with your Mini!
Akai AX-80
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Kevin Lightner
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Re: Problems with minimoog mod wheel

Post by Kevin Lightner » Wed Nov 23, 2011 6:46 am

torinkrell wrote:Its actually very easy to remove the mod wheel assembly from the Minimoog Model D. For the simplest attempt at this repair you don't even need to detach the connecting wires. If you unscrew the two frontmost screws of the mod assembly the whole thing can be gently pulled out. Then unscrew the Molex connector from the side wall and pull its two halves a half inch apart and push it back together a few times as described above. You may initially need to gently pry it apart. All this is assuming that your VCO 3 is working correctly so you may wish to put VCO 3 into audio mode to see if it is functioning first.

Beyond this it would be best to get advice from one of the real techs on this form after looking to see if possibly this topic is covered in the archives here.
Best of luck with your Mini!

I'm not sure what you have in your Minimoog, but the connector in a mod wheel section is normally a Cinch-Jones connector, not a Molex.
Only one side (the male) is usually screwed down and doesn't need to be removed unless you're replacing it.
The other side (female) is usually held on either by a wire tie or simply by friction.
I agree that corrosion can cause problems too, but the cure suggested probably won't last very long.
Furthermore, it sounds by the description that it's not in the wheel section at all, but in a circuit known as the modulation mix amplifier.
Hard to say, but probably best if you have an experienced tech work on it than attempt repairs yourself if you don't feel confident of working on electronics.

Also, taking out the mod section is easy, but putting it back in can sometimes be tricky.
The rear of the mod section has a small section of aluminum that must fit into a groove in the wood case towards the rear.
Miss the groove and the mod section won't lay flat and sometimes won't even push in far enough to be screwed down at all.
Better to be king for a night than schmuck for a lifetime. - R. Pupkin

Technician Larry
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Re: Problems with minimoog mod wheel

Post by Technician Larry » Fri Nov 25, 2011 1:18 pm

Also, taking out the mod section is easy, but putting it back in can sometimes be tricky.
The rear of the mod section has a small section of aluminum that must fit into a groove in the wood case towards the rear.
Miss the groove and the mod section won't lay flat and sometimes won't even push in far enough to be screwed down at all.

Kevin Lightner
About half the Mini's I've seen have two sets of holes for mounting the left hand controller. One set for when the sheet metal is properly inserted in the slot, and another set for when it is not. I probably created an extra set myself once back when I was not paying enough attention to understand what that alignment issue is.

torinkrell
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Re: Problems with minimoog mod wheel

Post by torinkrell » Fri Nov 25, 2011 2:34 pm

Molex = Bollocks! Thanks Kevin for setting me straight here. I always respect your amazing expertise and your willingness to spend time to give advice on this forum. My goal here was to suggest what I considered a simple repair that can be carried out by careful amateurs with some basic skills. I had what sounded like exactly the same problem with my Minimoog Model D and avoided a ($50 - $100 or more) repair bill by going through the process I described. I unscrewed my Cinch-Jones connector from the sidewall so I could work it back and forth without stressing the connector as much (and also so I could have better access to clean out the corrosion). In the end this amateur "repair" worked for me but as always others may experience different results. I certainly understand that many of the more difficult repair situations a pro tech like you come across are those caused by misguided amateurs, and will always defer to you and other experts on this forum. I am here to learn and after lurking for a very long time I am trying in my own way to contribute!
Akai AX-80
Korg Polysix
Roland Juno 60
Moog The Source
Yamaha e1010 BBD
Moog Parametric EQ
Sequential Prophet Pro~One
Altec AS-1600 audio oscillator (1947)
Moog Music Minimoog Model D (1973)

joyknobs
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Joined: Tue Mar 05, 2013 4:40 am

Re: Problems with minimoog mod wheel

Post by joyknobs » Wed Mar 06, 2013 4:28 pm

Hi all, new to the forum but I've been reading for awhile.

1st off...Sorry to bring such an old thread up again, but this info just saved me some cash.
I've had my Model D since 1989, got it for a hundred bucks in Youngstown Ohio.
It has only been in for maintenance once in all the time I've owned it.
Midwest Music Menders in Chicago. I think they are long gone now?

Anyway my mod & pitch wheels stopped working recently.
After looking around for local service centers I came across this info.
In less then 30 minutes I was back up and running.

After removing the module, I noticed my mini has extra screw holes
where the small wood piece screws into the frame.
(Just as someone pointed out in this thread)
It appears the whole assembly wasn't installed
correctly the last time someone removed it.
I was able to re-install the module using the original holes and it seems to fit much better now.
Before there was some give when you pushed on the buttons.
The whole top part of the module would move a little.
The slot in the back that the module slides into was being missed.
Now it is seated more firmly and doesn't move at all.

Just wanted to say that my mini and me are very thankful for the knowledge on these pages.
And now...Back to the lab.

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thealien666
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Re: Problems with minimoog mod wheel

Post by thealien666 » Wed Mar 06, 2013 10:46 pm

Welcome joyknobs !

And that misalignement of the mod wheel assembly is still a problem on the more recent Voyager, since it is held in place exactly the same way on the new machine ! I guess it is one more thing that the Voyager inherited from the original design of the Minimoog D... :roll: :lol:
Moog Minimoog D (1975)
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robertloud
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Re: Problems with minimoog mod wheel

Post by robertloud » Sat Aug 20, 2016 7:16 pm

Hey just wanted to chime in and say that my model D had this same issue, and I opened it up and reconnected the cinch jones connector a couples times and was in business. Great thread! Thanks :)

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