Help debugging a super-low output Thor.

[StereoKills]

This one's been sitting on the shelf for months waiting for me to debug. I figure today is the day.

Project: http://www.runoffgroove.com/thor.html
I etched my own pcb using the supplied layout by Pablo.
I don't think I made any substitutions.

Works great in bypass mode , but when turned on, the output is really really low. If I crank the Thor's volume all the way up, I can start to hear some nice distortion.

Voltages using a One-Spot power supply. Measurements taken with gain set to 50% and both bright and bottom switches on.

V+: 9.16

Q1 (2N5457)
D: 6.39
S: 0.43
G: 0.01

Q2 (J201)
D: 4.71 (Instructions say to bias this to 4.5, but adjusting the 20k trim seems to have no effect?)
S: 0.22
G: 0.00

Q3 (2N5457)
D: 9.16
S: 5.10
G: 4.15

Q4 (2N5457)
D: 4.65
S: 0.45
G: 0.00

U1 (TL071)
1: 0.74
2: 8.52
3: 4.28
4: 0.00
5: 0.73
6: 8.52
7: 9.16
8: 0.00

The very quiet distortion I can hear has me super pumped to get this working! I know this is going to scream when it's done!

[slacker]

Something's wrong round U1, pins 2 and 6 should be about 4.5 volts. I'd check all the connections and components round there, maybe pin 6 has partial short to pin 7?

D: 4.71 (Instructions say to bias this to 4.5, but adjusting the 20k trim seems to have no effect?)

If it does nothing then the wiper probably isn't connected.

[StereoKills]

Something's wrong round U1, pins 2 and 6 should be about 4.5 volts. I'd check all the connections and components round there, maybe pin 6 has partial short to pin 7?

I'm not seeing any possible shorts. Maybe the IC is bad? I ran out of sockets just before this project so it's soldered in (grrr).

If it does nothing then the wiper probably isn't connected.

That was my thought too, but I figured it was probably close enough at 4.7 to not bother with it?

[StereoKills]

Turned out to be a bad TL071. Got a new one in there and I'm basking in Marshall heaven.

Thanks Slacker!

[B Tremblay]

Glad to hear you got it working!

[StereoKills]

I've gotten it to work and it sounds great.
A bit of a curiosity though... When I use my bridge pickup, I can adjust my guitar's tone knob and the gain of the Thor to 'tune in' a high frequency/feedback tone. Shows up when the gain is between 50-90% and is loudest at 70%. Turning my guitar's tone knob up increases the volume of the frequency. Doesn't show up when I use both of the humbuckers, just the bridge one.

[StereoKills]

Apparently it's only an issue when it's the only pedal in the chain. In between my wah and delay's buffers, it's not there.