I'm trying to trace down a problem with my fuzz face I just built - I'm using a signal tester to see where the sound stops- but I'm not exactly sure where there should and shouldn't be sound.
I'm using this curcuit
(http://fuzzcentral.ssguitar.com/fuzzface/fuzzfacenpnschematic.gif)
I was just wondering if someone could tell me how the sound travels so I can check to see where it stops? I know this is a pretty simple curcuit, but I'm still learning to trouble shoot pedals any help is appreciated :)
THANKS
Hi, post your voltages at E B and C of Q1 and Q2. Also, which transistors you used.
Someone will tell you where the problem lies from them.
Have a read of the debugging thread too.
Good Luck
thanks for the response, I'll do that. I took a look on the way out the door and noticed that the 8.2k didnt look right I looked at the pack and there are two different resistors in the pack( even though it says 8.2k)- 8.2k and 820k, and I used the 820k. I jsut grabbed and didnt measure. Ill swap that and see if it fxed it.
ps. spelling brought to you by smartphone ;)
I just finished repairing my clone and tried some 2N956 metal can silicons with a gain of 100 and 115 hfe. I've now nailed the early 70's David Gilmore tone from Dark Side and Obscured By Clouds. May sure you can bias your Q2 to taste, I added an external 10K pot to make it easier and usually do it by ear.
I've built many fuzzes over the last year but the Fuzz Face is my favorite go to rock pedal.
Chris
Quote from: teletroy on September 24, 2008, 07:56:32 PM
I was just wondering if someone could tell me how the sound travels so I can check to see where it stops? I know this is a pretty simple curcuit, but I'm still learning to trouble shoot pedals any help is appreciated :)
Substituting an 820K would definitely quiet things down...
To answer your original question:
1) Probe both sides of the 2.2uF capacitor before Q1. You should have sound at both points.
2) Probe both sides of the 100K resistor between Q1 and Q2. You should have sound at both points.
3) Probe the junction of the 33K and Q1's collector. You should have sound.
4) Probe the junction of the 8K2 and Q2's collector. You should have (loud) sound.
5) Probe the junction of the 8K2 resistor, 330 Ohm resistor, and 0.01uF cap. You should have (loud) sound.
6) Probe the junction of the 0.01uF cap and lug 3 of the volume pot.
thanks for all the replies, I'll hopefully be able to swap the resistor tonight. If it doesn't work after that I'll follow circuit with the probe!
I currently have NTE123 (bc108 equiv) in it, I'd like to nail the Gilmore tone too- once I get it working maybe I'll try some 2n956s too :icon_mrgreen:
It should work with the the correct (8K2) resistor.
I believe now that stage is biased at cutoff right now.
It works so much better with the 8k2 - yeah! ;D
thanks all
Nice..I was pretty sure that was your problem.
Might still wannareplace that resistor with a 15K trim pot though so you can bias the stage to your tastes.