Moog 911 EG mistery!

[zarone]

Hi all
I am calibrating my Moog 55. One of the 8 EGs is completely different from the usual ones. It is a very early version, with more components / caps, no trimpots at all, no possibility of calibrating offsets, glitches etc. It is dated May 3 1968 on the yellow tag. I have not found any clue or schematics about it...
The problem is, it does not work properly: with all of the pots counterclockwise, at the minimum, the sustain works but there is asmall amount of slow attack. When I raise the attack pot (T1) until 2 ms, the envelope returns snappy, but the sustain is steady at the maximum. At higher values of the T1, the attack works as it should.
Any help is appreciated

Ciao
Fernando

[Kevin Lightner]

I first replied to ask if there were 100 ohm resistors inline with the pots for times (A,D,R), but in looking at your photo, I think there are.

You might check to see if the attack pot is ok by shorting it with a jumper or using an ohm meter.
Other than that, you might consider adding the 3 trimmers later models have.

[thealien666]

Sounds like maybe a case of a dirty/worn Attack Allen-Bradley pots near, or at minimum position (easily checked with Kevin's suggestion of shorting out the pot) ?

[zarone]

Kevin,
I shorted the T1 pot, but nothing changes.
I guess something was changed (the Philips cap is not original, IMO) but without a schematic diagram it is very difficult to understand what...