Fuzz face clone problem HELP please!

[caseyf]

As a first pedal build I put together a Silicon NPN Fuzz Face clone following this schematic: http://fuzzcentral.ssguitar.com/fuzzface/fuzzfacenpnschematic.gif

So I put it all together But when I plugged it in to test it all I get is a hum. If however I put my finger on the point where the negative of the 9V battery is soldered to the ring I get the a clean guitar sound coming through the under but still under the loud hum. There doesn't seem to be any fuzz and the fuzz pot doesn't change anything, onl the volume does.

I wasn't sure about what to connect the input and outputs to so that might be the start of the problem.. anyone?

Casey

[LucifersTrip]

to help, we'll need, at bare minimum, the transistor voltages (hopefully you have a meter)...and clear closeup pics will definitely give others a good chance to spot an error.

did you breadboard it first to see if it worked?


good luck

[caseyf]

to help, we'll need, at bare minimum, the transistor voltages (hopefully you have a meter)...and clear closeup pics will definitely give others a good chance to spot an error.

did you breadboard it first to see if it worked?


good luck

Thanks for that link, I just found this site. I'll check the voltagesme or my dad cant figure out the problem I'll come back with pics. Thanks.

[joegagan]

just remember, whatever is wrong, you can figure it out. follow logical steps, read the guides, you can do it! if you get frustrated, take a break but keep your eye on the finished result. it is so exciting when you finally get to hear something you made yourself roar

[caseyf]

Measured voltages

Voltage at the circuit board end of the red battery lead = 8.86
Voltage at the circuit board end of the black battery lead =0

Q1
C =8.55
B =0
E =0

Q2
C=8.7
B=8.5
E=

and just after this, I checked the voltages of the others again and they're all 0, not sure what happened. Maybe faulty meter.. but didn't manage to get emitter of Q2

Also, I changed the 20uF capacitor to a 22uf because I couldn't find a 20. And the layout of the PCB is very much thrown together according to the circuit diagram, couldn't copy one because of the sort of circuit board I used

[caseyf]

Will upload pics when i find camera

[PRR]

Fix your meter.

Q1 B should be like 0.6V, not zero.

Likely causes: short near Q1 B, reversed input cap, not-really-connected 100K, or not-connected Q2 E to FUZZ pot.

[caseyf]

Fix your meter.

Q1 B should be like 0.6V, not zero.

Likely causes: short near Q1 B, reversed input cap, not-really-connected 100K, or not-connected Q2 E to FUZZ pot.

Okay, meter wasn't broken, when put across the battery it shos 8.8V, then when probing the transistors that were 8.5V or something volts before, they are now between 0 and 0.05V

As far as I can tell, all those likely causes are fine. Apart from a short near Q1 B, not sure how to tell if that's the problem

[LucifersTrip]

 still, post all the correct voltages when you get a chance...

[caseyf]

still, post all the correct voltages when you get a chance...

Well I measured them all, but now they all appear to be 0V as if a wire came loose, but everythings exactly the same..

[joegagan]

ok, go back to the troubleshooting guide. track every trace, test each one for correct connection, and also test for things connecting that should not connect. this is where the problems are. forget voltages for a minute til you do this. something is shorted or not connected right.

[PRR]

> As far as I can tell, all those likely causes are fine.
> now they all appear to be 0V

If it was "fine", it would be working and showing reasonable voltages.

Electrons are VERY fussy little things. If everything is right, they are forced to do what we built; but one little thing not-right.....

[caseyf]

ok, go back to the troubleshooting guide. track every trace, test each one for correct connection, and also test for things connecting that should not connect. this is where the problems are. forget voltages for a minute til you do this. something is shorted or not connected right.

Checked everything for connection, but haven't tested things connecting that shouldn't be, probably the problem, thanks

[caseyf]

Okay so the meter problem is fixed, and same measurements, VERY little voltage on the base of Q1 but not 0V as I said before. Same again, The 100K, Fuzz pot and 2.2 cap are all connected properly. I will try replacing Q1 with a new one and see what the voltage is then.

[petemoore]

  Not to be overly picky, but what's the value of the fuzzpot ?
   Count the number of connections at 1 node [pick node 1 to check on], and note the polarized markings of the schematic of any components with a lead to that node.
  Use the DMM to count the node connections on your board, observe polarity wherever there is a marking which 'doesn't turn around like TOT', ie if one side has an arrow or a line or a _ or a + marking...count it as as relevant as anything.
   Starting at the battery clip node might be a good place, see that every node past a battery pole [note polarity] actually makes a connection to, or 'through to' the board...trace each side of the PS through whatever it goes through [shown on schematic].
  Measure every resistor [they help set up/adjust DC bias], I used 470k instead of 470 in a few FF's.

[caseyf]

  Not to be overly picky, but what's the value of the fuzzpot ?
   Count the number of connections at 1 node [pick node 1 to check on], and note the polarized markings of the schematic of any components with a lead to that node.
  Use the DMM to count the node connections on your board, observe polarity wherever there is a marking which 'doesn't turn around like TOT', ie if one side has an arrow or a line or a _ or a + marking...count it as as relevant as anything.
   Starting at the battery clip node might be a good place, see that every node past a battery pole [note polarity] actually makes a connection to, or 'through to' the board...trace each side of the PS through whatever it goes through [shown on schematic].
  Measure every resistor [they help set up/adjust DC bias], I used 470k instead of 470 in a few FF's.

The fuzz pot is an A1K pot. Sorry didn't understand much of you're advice about nodes :/. I just measured every resistor and they are what they should be according to the schematic, are you recommending I need to replace the 330?

[chromesphere]

Hi Caseyf,
I made this video a few weeks back.  Its part of my "how to build a guitar pedal" series of videos and is aimed at newcomers to the diy stompbox world.  Its some of the troubleshooting steps i use to fixing effect problems, both wired up inside an enclosure, and circuit testing.  Anyway, check it out, i hope it sets you on the path to solving the problem!
Paul

DIY Guitar Pedal Tutorial 9 - Fault Diagnosing
http://www.youtube.com/watch?v=JnD4-_Fhd90

[caseyf]

Hi Caseyf,
I made this video a few weeks back.  Its part of my "how to build a guitar pedal" series of videos and is aimed at newcomers to the diy stompbox world.  Its some of the troubleshooting steps i use to fixing effect problems, both wired up inside an enclosure, and circuit testing.  Anyway, check it out, i hope it sets you on the path to solving the problem!
Paul

DIY Guitar Pedal Tutorial 9 - Fault Diagnosing
http://www.youtube.com/watch?v=JnD4-_Fhd90

Hi, thanks I probably need to watch all of them

[caseyf]

Okay, I just made a completely new one, new board and components because I had spare. New boards much more neat and laid out better than the last one. EXACT same problem. Not enough voltage on the base of Q1(there is 0.1V). So if I managed to get the exact same problem when making it twice does that mean the schematic isn't correct? Like I need to change some components??

[LucifersTrip]

Okay, I just made a completely new one, new board and components because I had spare. New boards much more neat and laid out better than the last one. EXACT same problem. Not enough voltage on the base of Q1(there is 0.1V). So if I managed to get the exact same problem when making it twice does that mean the schematic isn't correct? Like I need to change some components??

that schematic is good, so sadly, it seems you're making the same mystery mistake as before.

I just realized (unless I missed it) that you haven't told us what transistors you were using...or whether you measured their gains.

...and we still need all voltages for both transistors....and of course, pics always help.

good luck