GGG EA Tremolo Debugging (Help!)

[coelacanth]

Kit: General Guitar Gadgets EA Improved Tremolo
Problem: LED works. Volume pot works. A very nice clean boost, but no pulsing effect at all.

Q1 and Q4 voltage values are very similar to what's in the GGG's documentation.

Q1:
E: 0.96
B: 1.44
C: 6.13

Q4:
D: 9.25
S: 4.75
G: 3.08

It says in the doc that the voltage of Q3's Collector should be variable (Speed Knob). However, I always get 0 regardless how the knob is set (0, half way up, or maxed). I have checked the wiring digrams several times, and I can't see anything connected incorrectly.

Has anyone here experienced a simliar problem? I'm fairly new to this whole pedal building stuff. I have successfully built a few tube screamers in the past, but I'm totally stuck with this one at present.

Thanks a lot in advance.

[coelacanth]

More info to be added;

Every part I used is what  comes with the kit.

Q1: 2N3904
Q2: J201
Q3: 2N5089
Q4: J201

The pins of the transistors are connected correctly from what I can see. I'm just wondering if there's any obvious mistake I've made.

Thanks.

[maarten]

Your problem is in the right hand part of the schematic; voltages on Q1 and Q4 won't help here.
No voltage on collector of Q3: are you measuring at Q3? Maybe there is a voltage at R18 --> bad connection between R18 and Q3. If there is no voltage at the other side (connected tot the supply) either, then connect R18 properly.
If there is +9 volts at one side of R18, and 0 volts at the other side then there could be a shortage somewhere. From R18 to ground there are several routes (the 470n cap, the 5089, 2M2, 1 uF: disconnect each of these a a time and measure the voltage at R18 again: this should give you a clue to isolate the problem; if necessary proceed methodically...

Good luck, Maarten

[flintstoned]

Check for continuity between Q3 and speed knob with your meters continuity function

[coelacanth]

Your problem is in the right hand part of the schematic; voltages on Q1 and Q4 won't help here.

Thanks, good to know.

No voltage on collector of Q3: are you measuring at Q3? Maybe there is a voltage at R18 --> bad connection between R18 and Q3. If there is no voltage at the other side (connected tot the supply) either, then connect R18 properly.
If there is +9 volts at one side of R18, and 0 volts at the other side then there could be a shortage somewhere. From R18 to ground there are several routes (the 470n cap, the 5089, 2M2, 1 uF: disconnect each of these a a time and measure the voltage at R18 again: this should give you a clue to isolate the problem; if necessary proceed methodically...

Good luck, Maarten

R18 you mentioned is the R18 in this document as well? http://www.generalguitargadgets.com/pdf/ggg_eat_lo.pdf?phpMyAdmin=4a28f86a515b7883e7bc35a68d4e7b6d Sorry, I should've posted the link in the OP.

If so, from R18 to grounds, R18 (15k), C4 (470nF), Q3, R9 (2M2), C6 (1uF) and R10 (15k), am I correct?

I'll measure the voltage of the R18 on both ends and report back.

Thanks for the help guys. Really appreciated.