Moog Concertmate MG-1 Mods

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TheDegenerateElite
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Post by TheDegenerateElite » Wed Feb 18, 2015 8:30 pm

Image

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mad_magician
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Post by mad_magician » Wed Feb 18, 2015 8:35 pm

so these are caps, see how they are barrel shaped?

http://upload.wikimedia.org/wikipedia/c ... r_code.jpg

These are Inductors, a bit more curvy ;)

https://encrypted-tbn0.gstatic.com/imag ... 7FXriLdYLw

facon
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Post by facon » Wed Feb 18, 2015 8:38 pm

I don't have one of mine, but I found this already posted. You can see that they are larger than the rest of the resistors. It's hard to make out the color code.

Image

This one is better. You can see C3 on the bottom left corner and C4 at the top left.

Image
Last edited by facon on Wed Feb 18, 2015 8:41 pm, edited 1 time in total.

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TheDegenerateElite
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Post by TheDegenerateElite » Wed Feb 18, 2015 8:41 pm

I used the chart posted to check values of some caps on my Moog Rogue board and they do indeed match the schematic values.

All lime green.


I suppose it does not hurt if you replaced them with other ceramic caps, but any sound or performance change is likely in the ear of the beholder and not real.

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home_listening
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Post by home_listening » Thu Feb 19, 2015 1:43 am

This isn't a big hassle to get around, Wire a little board with 3x CD4013 as a replacement - Worked well on a LM3216 replacement in a Roland SH-3a

calaveras wrote:While I'm refurbing my MG1 I have run into pretty much only one part I can't find. You guys are thinking top octave chip, but there is a guy that makes a modern equivalent.
I'm actually stumped trying to find the aluminum toggle swtiches?
I know these are used on some other Moogs of that era, and pretty much any hifi from 1970-1990, so it is cracking me up that I cant find them.
Any one hipper to sourcing than me got a clue?

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mad_magician
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Post by mad_magician » Thu Feb 19, 2015 9:17 am

Another quick question:

I am seeing flecks of black goop all over the place on that board. Is that residue from foam that deteriorated?

If so, It is a common issue with Hammonds of the 50s-70s and can be damaging to metal parts. clean that off with component safe cleaners.

Replace the foam with felt.

facon
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Post by facon » Thu Feb 19, 2015 9:20 am

mad_magician wrote:Another quick question:

I am seeing flecks of black goop all over the place on that board. Is that residue from foam that deteriorated?

If so, It is a common issue with Hammonds of the 50s-70s and can be damaging to metal parts. clean that off with component safe cleaners.

Replace the foam with felt.
That's just a picture I found online. The MG-1's have a well documented issue with the black foam they used. Every MG-1 needs to have it removed and thoroughly cleaned. I think it's part of the reason that resale value has stayed pretty reasonable on these synths.

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TheDegenerateElite
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Post by TheDegenerateElite » Thu Feb 19, 2015 5:26 pm

Rogues and others also have the foam.

It usually requires a full switch and slider replacement to get a synth running at 100% after removing it because it "conveniently" sits right between their tops and the front panel.

The stuff is very caustic and erodes metal, meaning that if it got on the slider contacts then no amount of cleaning will remove audio scratching. The switches can sometimes be saved, though the stuff can remove the surface coating of the switch toggles and leave them pretty shabby looking.

It even removes resistor/cap markings!

Luckily the pots are mostly sealed up, except for a small lube hole that you have to watch out for.

The residue come of easily with 99% isopropanol --- same stuff you use to remove rosin flux from pcbs.

basicbasic
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Post by basicbasic » Tue Apr 28, 2015 2:26 am

I did the Ringmod waveform mod today.

I followed the instructions for allowing Osc 1 to have switchable waves then tinkered a bit until I figured out how to do the same with Osc 2. At some point I think I shorted something cause the purple wire going to the Ring Mod circuit ceased to carry a signal but I managed to solder a wire from the top of Osc 2 slider to a point before input on the second board which seems to work.

In my opinion giving Osc 2 switchable waves into the Ring Mod yields more interesting tones for some reason. Anyway - thanks again to Facon for taking the time to document all that they have.

basicbasic
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Post by basicbasic » Sat Oct 10, 2015 3:00 am

Bumping this again to say thanks to Facon. I did the 'Minimoog' filter mod (meaty!),slowed the LFO right down so it can do proper sweeps, and extended the range of Osc 2 slider. Makes a rad little synth even better.

klangbauer
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technologie transplatn

Post by klangbauer » Sun Jun 05, 2016 3:25 am

Anybody know a working llink to
"technologie transplant".
My Moog MG1 needs restauration.

Thanks
www.klangbauköln.de

basicbasic
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Post by basicbasic » Sun Jun 05, 2016 4:26 am

I have a feeling they don't trade anymore. Plus there were lots of reports of terrible communication etc when they were trading. What do you need exactly?

infinitystairs
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Post by infinitystairs » Sun Nov 06, 2016 11:11 am

basicbasic wrote:Fan-friggin-tastic!

So questions (apologies for the noob-ness):
- I suspect I need a resistor as part of the VCF CV input as when I have the cutoff all the way down the filter seems to freak out and even the OSC pitch changes. Maybe my CV signal is too hot? Anyway, some help would be great.

Thanks,
Jamie
Hey Jamie I'm experiencing the same issue with VCF CV input... cutoff all the way down starts bending the pitch, then freaks out and pops.

Also, the range of external CV control is very limited. I'm sending a nice range from 0 to 5v, but I have to put the MG-1 cutoff at a specific sweet spot right in the middle, turn off contoured cutoff, and I still only get a very small range of sweep with external CV.

Any suggestions on how to buffer this or extend the range of external control?

basicbasic
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Post by basicbasic » Sun Nov 06, 2016 4:03 pm

Hmm - i'm trying to remember what I did in the end. From memory I think I added a resistor in series or maybe a zener diode to limit the CV range to avoid pitch issues. Most likely a resistor after trying a few values.

Mine now has pretty limited CV effect over the filter except when the tracking switch is at full so i'm not sure I chose the correct method in the end.

Sorry I can't be more help
Jamie

infinitystairs
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Post by infinitystairs » Wed Nov 09, 2016 9:58 am

Looks like most of the internal control voltages are 0 - 12v. My CV interface sends 0 - 5v. Should I figure out a way to scale it up to 12v?

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CollinRussell
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Re: Moog Concertmate MG-1 Mods

Post by CollinRussell » Sat Jan 09, 2021 8:52 pm

Got all the parts for these mods! MG-1 has been defoamed and degooed. Already replaced all sliders and switches. Bring on these tasty mods!
collinrussellmusic.com
collinrussellmusic.bandcamp.com

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