Hey guys. So I built this yesterday, it's my first build. I used oc75 transistors, and substituted a 25kb pot for the balance control. It makes fuzz, but there's a drastic volume drop when engaged, and the fuzz is very gated and scratchy sounding.
I've checked continuity everywhere and it all seems fine, except I have no voltage at Q3. Does this mean I have a dead transistor? I know I should have used sockets, but I was quick with the iron but do you guys think I killed it?
Voltages:
Q1
C -3.5 v
B -1.6 v
E -1.5 v
Q2
C -3.3 v
B -1.5 v
E -1.4 v
Q3
No voltage :(
(http://tapatalk.imageshack.com/v2/14/11/26/6464ef6c1086bcc24fb6898f9998e4bf.jpg)
(http://tapatalk.imageshack.com/v2/14/11/26/394b47dc3c386acd79d0d1adb56c9b11.jpg)
i'm looking at a PDF of the PCB. are your electrolytics in backwards?
Hi,
your electros are all in the wrong way, as mentioned by dont-tase-me-bro. Also, Q3 gets it's base and collector voltage via the balance and sustain pots. If you have turned them fully counter-clockwise, you won't get any voltage there...
correct the electros first and try again. most likely, that's the cause. Also make sure that your sustain pot is correctly wired (not visible on the pics)
if it doesn't work, report back. How are you supplying the -9V? are you using a road rage? if so, and the problem persists, show us some pics of that pcb as well.
Wow I feel silly. Flipped the caps around and it sounds much better, less gated and whatnot.
However the balance control doesn't seem to do anything, and there is still a volume drop compared to my clean signal. Is that normal for this circuit?
I'm getting the -9v from a battery. It also works off an isolated output from my voodoo labs pedal power using their 9v clip adapter.
Thanks for the help guys :)
So, a check with my meter shows no voltage to Q3 still, regardless of knob position. I'm wondering if the balance pot is bad, since it seems to do nothing?
I also forgot to mention that when I first completed the build I had the transistors backwards, could that have killed any components?
Your voltages on Q1 and 2 look correct, so I don't think you killed them. :)
Q3 on this circuit will not have much bias voltage on the collector, even with the balance pot cranked all the way up--it would probably be less than 1 volt depending on the transistor's leakage (0.8 or so?). I think your best way forward would be to swap out the balance pot for the correct value first. That way you can rule it out since 1) that pot does influence Q3 bias and 2) you won't have to go de-soldering that transistor again! ;)
I have a Buzzaround built on tagboard rather than the Bumblebee board, and it gets really loud quickly depending on how the timbre knob is set.
Yay, it works! In all my bumbling around and soldering/desoldering I had lifted the solder pad for lug 3 of the balance control. Fixed that and it's nice and loud. ^-^
Thanks for all your help, you guys rock!
Glad to hear it! It's one of the best fuzz circuits for sure.