Problem with Thunderpuss

[mjcyates]

So I built a Thunderpuss which should be one of the easiest builds ever, however, it is not working. Bypass is fine however no signal when engaged. I did probe around on the back of the board and whenever I touch the board with my finger in the area where Q1 R3 D1 and C2 line up I get signal. Seems like a grounding issue of some sort but I can't figure out what is going on. Any ideas?

[jimilee]

got any pics?

[mjcyates]

I will try to post some pics although not sure it will help much.

[jimilee]

I will try to post some pics although not sure it will help much.

Just by your post it sounds like it's not grounded well, but it could be anything. Check your values, and reflow everything and then see what you have. It's just helpful if you have pics to make sure you're not chasing your tail.

[mjcyates]

My camera is not the greatest so the pics aren't that good but here you go. I have looked pretty close and there are no solder bridges.

[wgc]

Solder joints at bot right of top picture look a little questionable.

And there's some spatter.  Cant see the jacks but could be a problem there too esp if you didnt use a wired ground and havent boxed it yet. 

Reflow everything and also check the tranny socket in the event it's too loose.

Good luck

[mjcyates]

Yes it is a little messy from replacing components. The joints look questionable in the pic but I have re-soldered them all and I think they are fine. My next step was going to be to remove the transistor socket all together and see if that might be the problem. Don't believe there are any problems with the jack and switch wiring.

[midwayfair]

Voltages?

Try sticking a regular transistor in there (2N3904 or some such). Does it work then?

Audio probe, make sure your sound is getting past the gate?

[mjcyates]

I am at a loss. Got rid of the socket. No dice. Tried 2n3904 no dice. Re-flowed all joints. Nothing. Whenever I touch the leg of C2 that connects to D1 with my finger it works.

[wgc]

Yes it is a little messy from replacing components. The joints look questionable in the pic but I have re-soldered them all and I think they are fine. My next step was going to be to remove the transistor socket all together and see if that might be the problem. Don't believe there are any problems with the jack and switch wiring.

Fyi Not trying to be critical, just want to help...

You might have a bad pcb.  I built a sho nuff v2 not long ago with pcb mounted switch.  Spent more time troubleshooting than building.  Didn't work at first at all.  Traced it to a defective diode, but it didnt work in BYPASS.  ended up being a bad trace between jack out pad and the switch.

It could also be a bad wire, so test that too, and easy enough to replace.  But wherever you have intermittently working things with pressure your problem is not far away.

[midwayfair]

It's not that big of a circuit -- go through and test every component for continuity to every other component on the board, and check against the schematic. Sometimes this is the only way to find a problem.

What you're describing when it works would bypass the transistor ... it would work because you're creating a connection from the input cap to the output cap.

Again: Can you take voltages? Jack Orman's site has the expected voltages for this circuit.

[mjcyates]

Ok I feel really stupid now. Since I could not get this figured out I decided to whip it together on vero. Dang it if I didn't have the same exact problem. I looked around on the amz website to see if I could figure something out. No luck. My last thing to try was I knew I had substituted a 68k resistor for the 62k resistor because I did not have a 62k so I thought I would tie some resistors together to get 62k and see if that would make a difference. Well guess what, it did. That didn't make much sense to me so I decided to check the 68k with my multimeter and low and behold it was 6.8k. Doh.... Thanks for your responses and wgc I didn't think you were being critical thanks for your input.