[sdiy] Bringing Minimoog Osc2 back to life

Tom Arnold xyzzy at sysabend.org
Thu May 14 21:56:25 CEST 2009

On Thu, May 14, 2009 at 10:38:29AM -0700, Travis Thatcher wrote:
> I've got a really nice early mini from my neighbor that I'm thinking of purchasing. Its in really good shape, apart from Osc2 being out.  I took it apart and inspected the voice board for any obvious problems. I verified that its definitely a problem from the voiceboard or before it, by taking audio from the osc2 saw output of the board as well as checking with a scope (nothing).  I swapped the 3080's (i don't have any spares) and no dice.  I replaced the 2 741s (ic4 and 5) with lm 741 chips.  I checked the trimmers, and they appear okay. i noticed that ic4 pin 6 is 5.26-5.33c while ic1 and ic6 pin 6 are each changing around, depending on note from 4.88 - 4.94v.
> any help would be awesome.

One thing that has always plagued me is the damn threaded clips that hold
the voice board in.  Make certain they are pushed up securely and add some
insulating washers if you have them.  I know this takes out OSC1 nicely, I
can't remember if it affects OSC2 but its quick and worth checking.

If the price on the mini is good, buy it.  I assume this is the middle model
with CA3046's and not ua726s?  At a good price, doesn't matter, buy it.
It's fixable. :-)

 - Tom Arnold       -  Free Synth DIY webspace http://www.sdiy.org 
 - SynthGeek        -
 - BBD Fanatic      -  "...is it a virus, a drug, or a religion?" 
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