This is my first experience with ge tannies. My zombii works and gets ok gain if it's set just right but the sustain doesn't seem to be there and I can't get any kind of oscillation out of it. I used a 68hfe for q2 and a 113 for q3. I have no idea where to start tweaking, was hoping someone could point me in the right direction... I don't have any buffer in front of, just straight into the amp. I've tried humbuckers and single coils into a traynor ycv80 and a blackheart handsome devil.
Do I need a higher gain on q2 or can I adjust a resistor to tweak the gain?
Or is a bias issue? I haven't had any experience with biasing yet. What I got in researching for a fuzz face is you bias at the collector of q2. Does that hold true for this circuit too?
http://www.madbeanpedals.com/projects/index.html (http://www.madbeanpedals.com/projects/index.html)
It's the zombii (I can't link to the pdf directly)
Thanks for any help!
> I can't link to the pdf directly
http://www.madbeanpedals.com/projects/Zombii/docs/Zombii_ver.5.pdf
Please review the debugging page (http://www.diystompboxes.com/smfforum/index.php?topic=29816.0).
Did you use a pre-made PCB or roll-your-own?
What voltages on each transistor?
This wacky zombii has an added complication, the "STAB" control. First check with this turned one extreme, then the other extreme.
Thanks for the direction (i.e. debugging page) and sorry my info was so incomplete! I used madbeans pcb and made no mods or part swaps. These are the ge trannies I used-http://transistor-spravochnik.ru/description/2sa221/8484 (http://transistor-spravochnik.ru/description/2sa221/8484)
Voltages-
Q1 c-1.75 b-.68 e-0
Q2 c-8.48 b-8.78 e-8.85
Q3 c-8.38 b-8.48 e-8.83
9v in 8.86
I watched and played along with the setting using in the pro guitar shop demo video of the fuzz factory so I went through all the settings and played with the full range of all the controls. It just really lacks gain and sustain and I can't get anything remotely close to feedback or oscillation.
Does turning the "COMP" and "GATE" pots change Q3 collector voltage?
Frankly, as I understand the circuit, there's THREE "bias" adjusters (GATE COMP and STAB) and I don't know how to even get it to "work", much less work as desired. Much less debug it for wiring errors.
I'll check that out tonight. Does the '0' on the Q1 emitter seem normal? I thought that was odd...
> Does the '0' on the Q1 emitter seem normal?
Look at schematic, or peep the PCB. Q1 emitter is directly connected to ground.
Just wanted to let you know I finally got this working. I just needed a different set of ge's. Sounds awesome now! Thanks for the tips. :)