MF-101 Amount Knob Repair

[ThomW]

Hey, just purchased an MF-101 off of EBay that has a busted amount knob. The entire envelope section seems to not work or to be turned to 0 on the amount unless the knob is pulled upwards slightly. The knob also has a good bit of wiggle and give to it.

I was hoping to get a good look at the pot by taking off the knob entirely, and from reading the forums it seemed to give the impression that the knob can just be pulled off with some even consistent force, but the fooger seems to creak and doesn't feel great when I start to pull on the knob. Does the nut underneath the knob need to be removed or anything else first? Or is it really just a consistent tug...?

[paramnesia]

[DonutDude]

If there is no screw on the side of the knob then you just pull it off. It really does take some effort. I used a mini flathead screwdriver underneath to help pry it off because my fingers kept slipping. The tools paramnesia shows would work as well if you have something like that in your tool kit.

[jsharpphoto]

I have used two spoons to remove knobs before. That way there is no scratch risk like there is with a screwdriver.

[facon]

Use a shoe lace to pull the knob off. No scratches or dents. It's possible the nut that holds the pot to the panel came loose, which then damaged a solder joint from where the knob connects to the PCB. This is a downside to board mounted pots. If it's a broken solder joint, you should just have to reflow it. It gets trickier if it lifted a trace.

[DonutDude]

I have used two spoons to remove knobs before. That way there is no scratch risk like there is with a screwdriver.

Good tip. I was lucky that I didn't scratch my ring mod but I was scared I might. Didn't think of using a shoe lace either. Good tips guys!

[jsharpphoto]

I have used two spoons to remove knobs before. That way there is no scratch risk like there is with a screwdriver.

Good tip. I was lucky that I didn't scratch my ring mod but I was scared I might. Didn't think of using a shoe lace either. Good tips guys!

I learned the two spoons trick from rebuilding vintage speedometers. Removing the needles (extremely fragile) without damaging the faceplate (extremely brittle).

[Bryan B]

There is usually a set screw in the knob. That should be loosened a bunch to pull it off.

If the knob is busted up, then the solder joints on the PCB (for that pot) likely broke loose as well. Even a small crack in the solder (which shows when you wiggle the pot a little) can cause problems in the operation or sound. You could reflow them with a soldering iron or send it back to Moog if you want to play it warranty-safe.