Neve 33609 J/D Gain Knobs Inoperative

[Spindrift]

The other day in a mix session, I noticed that my 33609 J/D was outputting about 3dB down on the left channel. This left channel is also the channel that makes one-time low-level crackles/pops within the first 30-60 mins of powering up. Once it does this, I don't hear it again until I power it on next time for a mix. (I've decided to just leave it powered on full-time now.) I was able to bypass, compress in / compress out a few times and get it to come back to normal even levels...but now the make-up gain knobs do absolutely nothing whatsoever. Every other part of the compressor seems to work properly, just now makeup gain on both channels...which seems odd and points to more of a control logic issue.

Well, I know that these units have some logic control issues and I've done the following within the last 18 months:

1) Recapped C16 & C18 on both channels
2) Deoxit Gold to the white board PIN connectors and reseated/cleaned them.
3) Deoxit Gold the the connectors/switches were it looked like it would penetrate into and have an effect
4) Re-seated the 4 ICs on the Control Board
5) Reseated the two amp cards

This morning, I un-racked it and performed steps 2-5 again with no effect, the gain knobs are still INOP.

Has anyone encountered this issue before or might know of what to examine next?

http://www.thehistoryofrecording.com/Manuals/Neve/Neve%2033609jd.pdf

Thanks,
Spindrift

 

[Spindrift]

Well, today, both makeup gain knobs are working great. Go figure. 

 

[Spindrift]

I found out that the source of all these troubles in my 33609J/D units come from the toggle switches failing. Once they are replaced, all is well with the units again.