No power to a TS9 Tube Screamer

[alange5]

Hello all,

  I inherited a 1983 TS9 in rough shape from a friend and I'm trying to bring it back to life.  I can't get power to the pedal, and no signal is passed whether engaged or disengaged.  Here's what's been done to it, that I know of...  One electrolytic cap replaced, one film cap replaced, new jacks, new IC chip, new battery clip.  All replaced parts appear to be correct values and installed with proper orientation.  I used my DMM to test for continuity and found no obvious issues in the traces and wires.  I figure the problem is in the input and/or switching.  I hooked my DMM to a battery, put a plug in the input, and began to check that voltage was making its way through.  I can read the battery's voltage on all components except at the input jack tip, the spot where the input reaches the board (yellow wire), and the first leg of the .02uf film cap attached to the input.  Pressing the switch causes no change in my readings.  I've done a lot of research but the FET switching of the tube screamer is beyond my comprehension...  Based on this info, and the pics below, does this point to an obvious problem?  A bad switch perhaps?  Incorrect switch wiring? A bad FET keeping the switch from flipping?

Any help would be greatly appreciated.

[slacker]

A bad switch would just leave the pedal stuck in bypass so you would still get a signal. I guess it's possible that a bad component somewhere in the switching circuit could result in no signal passing, I don't think it's very likely though.
When you say you can measure the battery's voltage what do you mean? What voltages do you get on the all the pins of the IC for example?

[alange5]

I was using the battery to test continuity, following the voltage through the circuit and making sure I was getting a reading.  I stuck a probe in with the + terminal and poked around with the other.  The battery was putting out about 7.5 volts, which I read across all the traces, except where the input jack tip meets the PCB.  I have not checked the voltage at the legs of the IC.  I am trying to wrap my head around the current flow from battery to LED (which is not lighting up), but I don't quite understand it...

[aron]

Keep going - I bet you will find the problem soon.

[alange5]

woo!  got it.  after much trial and error.... diode next to the 9v jack was no good, and the switch leads were reversed.  man oh man this thing was giving me a headache

[duck_arse]

that would be the protection diode. plenty of debate hereabouts as to the benefits of this type protection diode, as everything has been replaced anyway. they often indicate their failure with lots of scortch marks on the pcb and surrounding parts.