Fuzz face troubleshooting

[thetruthisgood]

I've been building a fuzz face with BC108B's according to the layout here on the right. http://www.pigeonfx.com/layouts/layoutff.html

*The bottom of the board is drawn like these 60's FF's http://www.freestompboxes.org/viewtopic ... 19&t=11697

When I plug the fuzz in to play, I get like a dead box. I pulled the pots out to make sure they weren't shorting, and eventually the whole circuit, but still no music to my ears through this box. I've tested with the Fluke MM and it's shown solid solder connections throughout, the resistors are in a decent range of where they should be, the battery works...

When I connect a black lead to ground and a red lead to the various pins of the transistors, C, B and E of Q1 (That's the one near the top of the board in these layouts) and Q2 all read out to 0VDC. From what I read, this is a problem.

Some things I suspect:
Faulty footswitch? I ripped it out of a rangemaster clone which similarly just didnt work (dead)
-If so, how do I check?

Transistor dead?
-How do I really check an NPN silicon transistor for proper function with a fluke 110? I've got four of these BC108B's, and I bought them listed at ~217hfe, their bags are marked at 216-217 hfe.

Improper grounding?- I don't have a FF enclosure with a bolt to the pedal enclosure at ground, so I ran a wire from the ground point to some copper foil tape adhered to an area of the enclosure which I'd nicked up.

[thetruthisgood]

[img]http://www.diystompboxes.com/pedals/DPDT.gif
[/img]

* I've also noted that the Diy stomp boxes page marks the proper DPDT wiring as this, which differs from what's listed on the pigeon layout..

[spaceace76]

you can't test transistors with a multimeter unless it has a transistor tester built in. more than likely your transistors are fine.

so you just get no sound at all, in either bypass or with the effect on? if your meter has a continuity check, it's very easy to check out a switch. does this circuit have the same symptoms as your rangemaster? if so i would suspect the switch.

what are the voltages at each leg of each transistor? if you're getting 0v at each pin then the transistors aren't turning on and won't pass audio. either your wiring is bad or your battery is bad. since no voltage is getting to the transistors, figure out how the voltage gets from the battery to the transistors and look for an issue there. at minimum you should be able to read something at the collector of each transistor, since there is only a resistor network between that point and the battery. since you're reading nothing, i'd guess that your traces are no good or something along those lines.

can you post a picture of your build?
you should hard wire the effect until you can be sure that it's working. worry about the switch later

[spaceace76]

the pidgeon layout has an input grounding true bypass switching scheme, whereas the DIYSB one is a straight-up true bypass scheme. the input grounding scheme is commonly used with louder circuits that have lots of gain, such as this one. either one will work fine.

[thetruthisgood]

Update: I found a bad solder link at the footswitch. Pedal is still on the fritz though. With a refreshed solder joint, the footswitch tests out OK. However, when the pedal is plugged in, I don't get the bypassed guitar signal when effect is off; when the effect is on I got a trebly oscillation and the guitar signal didn't register until the fuzz volume control was turned up. The guitar signal was then weak.

I then tested the transistor pins: black lead of multimeter to aluminum pedal chassis and red lead to C,B,E of Q1 and Q2. ~0VDC for all transistor pins. In fact, I could not find a DC voltage anywhere in the pedal except for on the battery itself. THank you for the reply.

[spaceace76]

sounds like you have a couple issues happening here. if you still aren't getting sound when in bypass then you likely have either a bad switch or you've wired it incorrectly. as i said before, try hard wiring the effect (board input comes right from the input jack, and board output goes right to the output jack) so that you can work on it without worrying about the switching just yet.

your transistors still aren't getting voltage for some reason. that's the first thing to figure out. you should be able to read something at the collector at the very least. your connections after the battery, leading up to the transistor's collector pin, have some issue. maybe a resistor is open or a solder joint is bad. i might be able to spot something if you can provide pictures.

also you should be able to read the battery voltage at the junction of the 330 and 33k resistors. if you get no voltage reading here then the problem is anywhere between your battery snap and this resistor. you can take the reading from the left side of the 33k resistor, provided the traces are the same as the 60's version and you followed the layout above.