GEQ Issues

[bpm91]

Have any of you had issues where it seems the GEQ has no affect when on? I seem to be having this issue with my Studio Pre (I know, rack-piece, but many share the GEQ in vintage).

I turned on the Pre today after having amazing tones about a week ago, no knobs changed... it has an overly treble, ice-pick sound. I fiddled with the GEQ on the lead mode but to no affect. I even tried extremes like keeping the 80 slider up all the way and the rest minimal... should give a heavy woofy blanket-covered sound, but this wasn't the case. It was just unaffected.

Things I done: I switched guitars, didn't work. I unplugged the Pre from the effects loop of the III and just used the III, III sounds normal (awesome).

Any ideas? It seems to be narrowed down to the Pre. Turning on/off the GEQ yields little change. Could it use a retube? I have no idea of the hours on these tubes.. they could very well be the originals.

 

[bpm91]

bump for help.

 

[Boogiebabies]

I would think that LDR #5 is bad and not shorting the GEQ to ground. With no ground reference, the circuit is just off. If you have test leads, you can take the GEQ circuit side of the LDR and clip it to ground and see if it comes on.

 

[bpm91]

I would think that LDR #5 is bad and not shorting the GEQ to ground. With no ground reference, the circuit is just off. If you have test leads, you can take the GEQ circuit side of the LDR and clip it to ground and see if it comes on.

Hmm... guess I'll have to find a tech.