T15 pot issue?

[tronnyjenkins]

My T15, after working fine for a couple of years, just recently decided to act a fool.
Basically, I can rotate the stepped gain knob all the way around, and it offers no actual gain. does this sound like an easy fix, or a bad pot?

[Branford]

Just suggesting the obvious: Are you sure that the knob is tight (e.g. the switch is actually moving from detent to detent)? You might want to remove the knob and try rotating the shaft sans knob (with channel-locks)... (just a thought)

[tpryan]

does this sound like an easy fix, or a bad pot?

It's only an easy fix if it's a loose knob, as mentioned above. It's not a pot, it's a rotary switch, and it's difficult to remove without damaging the PCB.

[tronnyjenkins]

I can see that now. That would require a good deal of patience to remove with only solder wick! Ugh.

It appears as though the person who assembled it didn't use the foil to hold the stop pin in place. That explains the free spin. Corrected that problem, but now I have a noise issue. The trim pot works to reduce it, but it seems as though the gain is very low. Now to troubleshoot that!

[tpryan]

Try a new U1 if all else looks good.

[tronnyjenkins]

If I get correct readings at +18v and -18v is the 1512 IC the likely culprit? I actually was mistaken... The OTHER t15 is the one with the gain problem! Doh!

[tronnyjenkins]

Try a new U1 if all else looks good.

The readings per leg are the exact same on U1 as on U1 of the correctly functioning unit. Please advise if you still suspect that to be the problem.