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Minimoog Sync Mod

Posted: Fri Nov 21, 2014 3:59 pm
by megavoice
Hello,

well, I'd like to go on with my mods and want to ask if there are people here who know about the Sync-installation of the last 10 Minimoogs with the golden badge and might offer me some pics so that I can get an impression what it looks like and what functions there are.......

If there won't be anybody there who'll teach me a better way, I'm going to sacrifice one of the two DC power supply jacks to prevent the housing of being damaged by drillig holes into. The second jack I've to keep for my S&H generator.
I'm going to put at that place two toggle switches, one for switching Sync on and off, and the other one for switching the Filter Contour on and off.
I think more than this needs not to be done. The electronic work for my tech is just a walk in the park.......

Re: Minimoog Sync Mod

Posted: Fri Nov 21, 2014 6:58 pm
by thealien666
I don't know about the Moog factory Sync mod, but I've done the one found on the web myself with ease.

As for the S&H, I've added it to my Korg Mono/Poly using this neat little 8 pin chip called LF398 (Sample-And-Hold-on-a-chip) easily found inexpensively and requiring only a minimal amount of external components.

Re: Minimoog Sync Mod

Posted: Sat Nov 22, 2014 2:11 am
by unfiltered37
thealien666 wrote:I don't know about the Moog factory Sync mod, but I've done the one found on the web myself with ease.
Could you point me to that? You say "with ease", but how hard is it for a novice?

Re: Minimoog Sync Mod

Posted: Sat Nov 22, 2014 3:07 pm
by thealien666
It all depends on your "novicity" level ? :mrgreen:

And also on your version of the oscillators board (regular one, or brand new one).

If you can solder two resistors and diodes (oriented the correct way) and some wires together, and find a spot for two toggle switches, you qualify... :wink:

http://www.synthfool.com/docs/Moog/mini ... i_mods.jpg

Here are some shots of my mod on my Mini:

Below we see the black wires tied together with red tie-wrap going to the oscillator board:
Image
The two chromed small toggle bats (the one on the right is VCO2 and the one on the left is VCO3, both for sync on or off, shown here in the off position):
Image
Here we see the two diodes (resistors are inside the red shrink-wrap (the connector is optional for servicing convenience only):
Image

Close-up of the wires connected to the toggle switches:
Image

Image

Re: Minimoog Sync Mod

Posted: Sun Nov 23, 2014 4:30 pm
by megavoice
Thanks Alain, for your suggestions and the subsequent pics :)
I googeld for the factory sync by myself but obviously it`s a hoax as the pics of one of that brass badged didn't show any mods in details outside. There's obviously only an additional CV output and a "Scale" button, don't know what for.
The first time of that strange sync mod I've been told from the most well known synth dealer here on this continent. He had one of these last 25 Minis in stock, but did't tell the truth.....strange.

As for the S&H generator I need no mod to do, as I've the original MOOG 1125 S%H module. I only wanted to tell that I need the second power supply for feeding it.....

I decided now to use a three posistion toggle switch, like on the T2 module....OFF, ON, and Contour.....

Re: Minimoog Sync Mod

Posted: Sun Nov 23, 2014 7:41 pm
by unfiltered37
Thanks for that, i will try it when I get a chance. Where did you get the switches, and will any do? I am guessing you have the new osc board, as do I with my 12k serial?

Re: Minimoog Sync Mod

Posted: Sun Nov 23, 2014 11:56 pm
by thealien666
Nop, mine is the middle model serial in the 7000. The most common. If yours is serial 12K it's most probably equipped with the most recent, newer oscillator board.

In that case, you simply need to look for the "sync mod for new osc bd" just below on the Synthfool page link I gave in my last post.

It's a little more involved since you need to build a small two transistors (one NPN and one FET) circuit, instead of simply two diodes/resistors. Really nothing a trained tech, or experienced electronics hobbyist can't do.
But most probably not a novice.
Sorry.

Re: Minimoog Sync Mod

Posted: Mon Nov 24, 2014 2:45 am
by unfiltered37
Is this right?

The 2n3904 is the NPN, whose base connects to IC8 (7th pin?), whose collector goes to +10 and the base of the FET, emitter goes to a resistor then to -10 and SW1 (the switch?). The FET source and drain connect to Q9.

Shouldn't be too hard, and the worst that can happen is it blows up, never to work again, and I am left with a software emulator, but it never really cuts it and I end up selling myself on the streets to buy another. Before I save up enough, though, I see someone selling a mg-1, and can't live another day without a moog, so buy it, and try to mod it and it blows up. Thanks for the advice.

Re: Minimoog Sync Mod

Posted: Mon Nov 24, 2014 3:12 am
by thealien666
BTW, there's also a disclaimer by Kevin about those specific mods, to try them at our own risks. I was lucky that the one for my board worked... :mrgreen:

Also, you're not that novice if you can identify transistor pinout on a schematics... :wink:

Re: Minimoog Sync Mod

Posted: Mon Nov 24, 2014 3:30 am
by unfiltered37
I took a beginner's course, but it's been a while, and had to look it up. But i have no idea where the switches are in your mod. mine looks like it has one switch.

Re: Minimoog Sync Mod

Posted: Mon Nov 24, 2014 7:09 am
by slirak
In the diagrams at synthfool.com, the old oscillator schema shows a sync mod where you can sync both VCO 2 and 3 to VCO 1, hence the two switches. The schema for the new oscillator board only shows sync for VCO 2->VCO 1.

I guess one could adapt the same solution for VCO 3 as well though? Question is, is sync for VCO 3 worth it? I haven't been able to find any demo of it. Someone here posted one on soundcloud a while ago (wasn't that thealien666?) but the link seems to be dead.

Re: Minimoog Sync Mod

Posted: Mon Nov 24, 2014 4:24 pm
by unfiltered37
Thanks, that makes sense now. I wonder if you could sync 1 to 2 and 2 to 3.

Re: Minimoog Sync Mod

Posted: Mon Nov 24, 2014 5:39 pm
by thealien666
In a sync configuration there's always a master and a slave, or slaves in this case. Whilst it is possible to choose a different master than VCO1, the ability to select another one would definitely complicate the sync circuit, though not impossible to do.

In my config, VCO1 is always master, and VCO2 and 3 are slaves that sync to the master.

Re: Minimoog Sync Mod

Posted: Tue Nov 25, 2014 5:41 am
by slirak
So what do you think, is adding sync for VCO 3 worth it? I guess it could be fun to sync it and then turn off keyboard control?

I have the new oscillator board, so adding sync is a bit more involved.

Re: Minimoog Sync Mod

Posted: Tue Nov 25, 2014 3:38 pm
by megavoice
Alain,

I had a pretty long discussion yesterday and I finally cannot see clear with your mod.
Obviously you've synced all three oscs. But how does itr work ???
If you're using additionally osc 3 is the second sync-synced. If yes, might be pretty interesting....
And what are your other routings ? Do you also have routed the Filter Contour on ?
It's even possible to rout the 3rd as an LFO. But then the Mini will look inside like the Memory :lol:
BTW, I'm pretty sure that I`ve the new board inside as mine is under 13000 below....