Trotskydrive troubles

[cheeb]

Built a BAR Trotskydrive. However, when bypassed signal passes fine; when engaged, the LED turns on but no sound. I installed a 2n3904.

I've checked and rechecked my switch and jack connections, looked everywhere for cold solder joints, and I don't know what's wrong.

When it's engaged, when I turn the knobs I get a scratchy sound and sometimes an extremely low guitar signal.

Any recommendations?

[Meanderthal]

 Didja check the tranny pinout? I believe the Russian tranny it was based on had a different pinout, but I might be wrong...

[dano12]

Hi Cheeb, like Meanderthal said--double check the pinout of the 2N3904 against the BCE pins in the schematic. Did you perf it or build it from my layout?

[cheeb]

I built it from the layout. Ninety bucks the pinout is wrong. Stupid me soldered it in though, because i was clean out of sockets. Now I have to take everything apart to get it out to try it. Thanks.

[ambulancevoice]

2n3904's have different pinouts to the russian
and use sockets, all the time, heat fries transistors
but, if you want to look professional, put an unwired crocodile clip or use that heat sink compound stuff on the leg bettween
the top of the pcb and the transistor and solder (DO EACH LEG AT A TIME, not all the same time with one clip)

[cheeb]

Okay I ripped a socket out of another build and fixed the pinout. All I'm getting is a loud SSSSHHHHHHH which is controllable by the knobs. In my frustration, I accidentally bent the socket over and the legs broke off and are now stuck in the solder pads. Any advice for getting those out and why all I'm getting is a SSSHHHH? AAARRRGGG!!

[ambulancevoice]

bent the socket?

[cheeb]

Not so much bent as just pushed it over too far and two legs broke.

Not a common occurrence by any means, I know.

I guess all I can really do is use my little pocket hand drill and hope I can drill them out.

Anybody know why all I'm getting is a volume/gain controllable SSSSHHHH?

[ambulancevoice]

did you use a 2n3904?

[ambulancevoice]

if you did, you gonna have to bend the legs of the 2n3904 to match the layout
http://www.covingtoninnovations.com/noppp/2n3904.gif
thats the pinout of the the 2n, which is c-b-e
and on the pcb, its layed out for the russian, which goes b-c-e

[cheeb]

Yeah I did that. That's when I got the SSSHHHH instead of no sound.

[ambulancevoice]

hmmmmmmm
try another socket
and make sure when you bend the legs that they dont touch
try the 2n2222

and keep in mind that it might not be the transistor

[cheeb]

I thought about that, but I don't know what else causes a SSHH. I've never experienced this before. Sorry to keep bothering.

[burnt fingers]

I sounds like you have white noise being amplified by the circuit so that is probably a good sign.  Check the input wiring, maybe you have a bad solder joint or something is cross wired.

Scott

[cheeb]

It works. I can't wait to test it on my Fender Bronco. I just resoldered the input and carefully soldered in a new 2N3904 and voila. Thank for all the help guys! Stay tuned for pictures on the pictures thread.

-Cory