Shin-ei FY2 problem?

[drewl]

So I built a Shin-ei Companion Fuzz FY2 yesterday and the output looks kinda funky.
Haven't tried it with a guitar yet, but the signal on the scope is looking pretty bad with not alot of output.
So far I've tried some 2n3904 &  2n2222 transistors hfe~200 or so.
I know the output filter lowers the amplitude, but I'm also getting -2.8v on the base of Q2.
Anyone know if that's right?

Edit:   Both stages are amplifying, but when the signal is mixed at the pot it's getting screwed up somehow.
          Also the output after the filter is definitely lower than the input signal.
Maybe I have a bad cap in there.

[Mark Hammer]

Verify the pinouts.  Keep in mind that sometimes what can be very common transistors, according to their number, can have different pinouts than you thought.  Datasheets can help, but there is sometimes no substitute for sticking the darn thing into the transistor socket on your meter and seeing that you get an hfe reading of 234 when you insert it as ECB but not when you insert it as EBC.

[drewl]

Heh, don't worry...they're correct.
Removing the .1uf cap to ground in the filter raised the output as I had read in some other posts, so I think I'll put a trimmer in between it and ground.
Of course I'll have to actually play guitar in it to tune it properly.

[gigimarga]

I have the same problem as you: only 2.9V on the Q2's collector instead of 6.6V claimed in the GGG's building instructions.
I i didn't find any solutions yet...

[drewl]

Is that negative (-) voltage on Q2's collector?
Mine is.

[Gus]

Good read about biasing
http://en.wikipedia.org/wiki/Discrete_Bipolar_Transistor_Biasing



Now this link has more predicable bias. You should be able to use 2n2222as, 2n3904s, 2n5088 etc
http://fuzzcentral.ssguitar.com/schematics/foxeylady2k.gif

[drewl]

Is that negative (-) voltage on Q2's collector?
Mine is.

Actually that's -2.9v on the base.
Anyway I boxed this thing up and tried it....whew is it fuzzy!
Compresses in a cool way, produces some weird sounds.