TS808 "no Gain" problem. Help Please!

[sevenisthenumber]

I got a TS808 reissue that the gain knob does nothing on.
Volume and tone work but the gain knob acts like it isnt there. Seems to be as if it were all the way down.

Heres what ive done.

1) Replaced the chip.
2) checked all solder joints/traces
3) replaced gain pot a500k
4) screamed!
5) replaced the two 1n418's just in case.

[petemoore]

  Do all the reading and writing involved with the Debugging page.
  Test for Short in the PS, take voltages at least, sometimes just the voltage measurements narrow down the problem..
  Application of RG's method should reveal the problems location quickly and that will help us find a solution.

[oskar]

Ok. You've changed the diod's so it's probably not them shorting the feedback. It's either a short in the feedback or an open connection in the 47n/4k7 net ( on the tonepad drawing ) going to Vb. I think the latter.
Most because of the dramatic effect if I guess right.   

[reverbie]

+1 to oskar

[R.G.]

"What to do when it doesn't work"