GGG EA Trem debug

[Plinky]

I have searched every thread concerning the EA Trem, and most of them are about the ROG version and few on the GGG version of this pedal, and not many successful outcomes (a lot of incomplete threads).

Here's the link to the circuit:

http://www.generalguitargadgets.com/index.php?option=content&task=view&id=108&Itemid=138

What it's doing, etc. - Pedal bypasses properly. When it is engaged, LED lights ok, only a clean signal boost is detected; no tremolo effect, depth(1M) and speed(25k) controls do nothing, level(25k) control works ok.

Voltages:

Q4 (2n5457)

D - 8.34v
S - 5.38v
G - 3.82v

Q1 (2n3904)

C - 5.83v
B - 1.37v
E - .739v

Q2 (2n5457)

G - varies ( < 1v)
S - 0v
D - 0v

Q3 (2n5088)

C - varies (up to approx. 8v)
B - .5v approx.
E - 0v

All the pinouts for the transistors appear correct. I etched the PCB myself using the transfer on the GGG site and double-checked it for broken traces (none that I can find).
Any help would be greatly appreciated.

[Plinky]

Please guys. If there's some place I haven't looked, at least point me in the right direction. Can't blame a noob for asking.
I've modded enough pedals and amps and such, I thought this would be no different, but I have been proven wrong.

[Seljer]

I'd check the orientation of Q2, those JFETs like to tease you with their pinouts

[Plinky]

That's what I meant by the transistor pinout (sorry for my misinterpretation). I double checked and triple checked the orientation with data sheets on the web.

[Pushtone]

Q3 (2n5088)

C - varies (up to approx. 8v)
B - .5v approx.
E - 0v

I opened mine up and took voltages. Pretty much what you have there with the exception of Q3 collector. Mine swings from 2V to 4.7V.
From the voltages it seems your LFO is working. Check the path from R5 to Q3 thru Q2 and the depth pot wiring. Check C3 for polarity.
As I recall the SPEED pot should be a reverse audio taper.

Thats all I can contribute, not much sorry,  good luck.

[Plinky]

I'm not sure what I did, but it's working right now.


I started checking at the emitter of Q1 (about .737 volts), then traced it through R5 (.679 after) & R6 ( .679 in, 0V out) to C3 ( .679 at the + lead, nothing out, orientation correct). I lifted one lead from both R5 & R6 and checked resistance - all within specs (about 177 & 1.18 ohms).  I decided to replace C3 and resolder the resistors back in, and it started working. My voltages did didn't change all that much (I would say maybe .02 of a volt). My only guess is I might have had a cold solder joint that wasn't quite visible (just enough continuity, but not enough for the proper signal). Thanks for the help Pushtone. Now if I can get my ITS8 from frying batteries, I'll be on top of the world.