Zvex Wooly Mammoth Clone Debugging

[natron_mn]

I posted about perf/vero builds being impossible. Folks asked for pictures/more info. Now that I've (unsuccessfully) finished another vero build I've got some more detail.

I used the following layout: http://tagboardeffects.blogspot.com/2011/02/zvex-woolly-mammoth-vero.html

I probed the back to ensure the traces were fully cut, and that each row wasn't connected to another row (save for the jumper). That is, I checked for solder bridges, and didn't find any.

I am getting V+ (9.8V) on all pins of the transistors (2N3904s), with the exception of the collector of Q1, which measures slightly less than V+ (about 8.5V). If each pin on the transistors is measuring the same as the input voltage, what does that suggest? Obviously that is very incorrect.

I also hear a pretty audible pop when I bypass the effect.

[vigilante397]

You may have fried your transistors. Did you verify the orientation before soldering them in? That can often be bad news.

I would also recommend renoving it from the box and disconnecting the switch for debugging. Not that I don't trust you, it just helps sometimes to renove a few variables. Double check off board wiring (especially anywhere ground is supposed to be connected) and I would recommend wiring your in/out jacks straight to the board (just for now).

I've built this pedal before with this layout, so I can promise you it works. We'll get to the bottom of it!

[antonis]

I also hear a pretty audible pop when I bypass the effect.

Place a 1M - 2.2M resistor between In & GND and wire your 3PDT switch as shown left below - wire also indicator LED as show right below just in (rare) case of LED popping..
(your OUT doesn't need a pull-down resistor 'cause is already grounded via the 10k Pot..)

[Slowpoke101]

Check the ground wire going to the board. If you are reading 9V (or so) on the all the transistors there is a good chance that this wire is not connecting to the power ground. It is a bit difficult to trace the wires from your pictures so I can't really see where you have got it connected. I think that it may go to the stomp-switch board. Remove the wire from this board and connect it directly to the DC connector's ground connection and check your voltages again.

[antonis]

If each pin on the transistors is measuring the same as the input voltage, what does that suggest?

Short-circuited transistors AND open GND way..
(although that's unsual..)

In case of only open GND, you shouldn't read anything on Emitters (BJTs in off region) and in case of only short-circuited BJTs you should read a voltage proportional to their Collector/Emitter resistors ratio..