Moog Werkstatt VCO kill switch / mute? (resolved)

[part12studios]

Hi everyone,

So I finally got my hands on my first official moog product. The werkstatt which was exciting because it's affordable (though the MCV4 I got for it made it less so, but I wanted MIDI CV for more than just the moog)..

One of the big attractions was that it does have external audio input which I thought would be great to run things through with a genuine moog filter but there was a catch. The VCO is always audible.. sooooo

I was wondering if anyone out there knows a safe / easy way to allow me to mute / disable the VCO on one of these bad boys. I'm looking to have a local electronic repair guy do the work as I don't trust my impatient hands on a device like this with a soldering iron

This is the motherboard



One thought is maybe the switch that selects square or saw could be given a 3rd option that's none?

Does anyone know a simple way to do this? it seems like it would be a popular mod for virtually every werkstatt owner to have done because who wouldn't want a VCO free external input feature? I tried to moog forums and got crickets which is surprising. So I figured I'd see if anyone here knows something about it because this community is pretty awesome

Thanks,
Caleb

[meatballfulton]

Trace the etch going to the VCO direct out back to locate the actual output of the VCO circuit at SW1A (see schematic). Add your switch there. It might be possible to simply replace SW1A with a different one.

If you don't already have the schematics, download them here.

[abruzzi]

my memory on this is fuzzy, but on that image on the right side where it says JMP57, there is actually a jumper connecting both sides. cut that and the VCO won't enter the filter. Solder in a switch if you want to turn it on or off.

[part12studios]

Hi there, thanks so much for this reply! I STILL haven't heard back from anyone in the Moog forum about this after several bumps.

That does sound like it will be easy to do without harming anything else, which of course is a big concern. that disabling it might impact some other core functionality. you would think it doesn't and be indepenent, but this is not something i've done before.

I'm sorry I didn't reply till now but I forgot to check "email me" for this thread and just been crazy busy so it fell off my radar.

I'll report back what I end up doing and how it went.

Thanks!
Caleb

[part12studios]

Ok so I had the operation done. pin 57 appears to do the trick. When it was still disassembled I was worried because of some noise issues but i realized the adapter board wasn't screwed in which acts as a ground.

there is a jumper there, removed it and put two wires to a switch. very nice indeed.

So yea works really nice now. Thanks for the input!

i tried to embed the image but it wasn't working but here it is.
https://www.dropbox.com/s/22jw2udqtnjgb ... 6.JPG?dl=0

[part12studios]

here is a video of the end result. I should have taken photos while it was open, but honestly it's so simple, it's not needed. JMP57 has a jumper in it.. remove that and put two wires from those points to a switch. find a good place you want to mount it and boom.. i will say the one is expect to put the switch on one of the sides because the mother board and the adapter card to the right effectively use up all of the top space and leave little gap for even a smaller switch's under surface guts to not bump into it.