Help Please !!! - Marshall SUPA FUZZ

[TIMBO]

Hi guys, Had some time to kill and thought i'd try a pedal build.I found a FUZZ FACE schem on FUZZ CENTRAL.Looked easy enough. Hit the net to find some info on the transistors. Got all i needed from the local shop.Made up PCB (trace provided by Fuzz Central)and loaded the board and added a true bypass.Even used a clip on the Transistors for a heat sink.Used PNP transistors and positive ground and a final trace.Pluged it in and WELL the bypass works but nothing else???
Checked all the joints, Nothing

Had another thought, maybe it was that it was because i had it as a POSITIVE GROUND.
Rebuilt it as a NEGITIVE GROUND and used NPN transistors
Rechecked all joints
Plugged it in and DEAD QUITE but the bypass still works


Can anyone help, Thanks

[plexi50]

I have built a few Fuzz Face box's. Make sure you have the bias trimmer adjusted to 4.75 volts or near that range if you have used a pot in place of the 8.2K resistor

Also there are some fake transistors out there especially on Ebay. There are so many different schematics that i dont know which one you have built

Do you have any pics of the board and pot wiring?

[Cups]

If you're getting no sound when effect is engaged you probably wired something wrong. Can you post pictures of your build? A bias for a fuzz face can be anywhere really and you'll still get sound.

[TIMBO]

Hi guys, sorry for the delay.I've tied a few things and its all been a bit confusing.First of all i need to find out if it is ok to build this with a positive ground. As i see it if it is a positive ground would plugging the lead to the amp that is grounded just short the 9v supply straight to ground. I did find some AC128 transistors and would like to use them, but they don't like you to use them in a negative ground circuit. I'm trying two fuzzs an ARBITER FUZZ that is similar to your schem and is wired as a + ground, Traced over it and no joy. The other is the marshall, schem below. I didn't think this was going to be so difficult. Thanks

[sluckey]

As i see it if it is a positive ground would plugging the lead to the amp that is grounded just short the 9v supply straight to ground.

Don't think of it as if you're shorting out the battery. All you're doing when you plug in is to connect the + battery to ground, just as if you had turned on a switch.

You can't just flip the ground system between positive or negative by changing from PNP to NPN. There are other considerations too. You must look at the schematic and determine if you need to reverse the polarity of any electrolytics and diodes.

There's nothing wrong with using a positive ground. Most of my pedals use positive ground. Just stick to your original circuit and transistor type and find the problem (most likely a wiring error or transistors not connected properly).

If you have switched battery polarity with transistors in circuit, it's likely that the transistors are now shot.

[TIMBO]

Thanks Sluckey,I used some cheep transistors for these first builds because i was unable to get the ac128 over the weekend,also this way i could get it up and running and then change them over.I'll do up a full schem because there is a true bypass and i'll will be using a wall wart PSU.There is also a few extra components been added, so i'll strip the board and start again.Thanks

[TIMBO]

Hi guys, Two schems just to make sure were on the right track. Thanks