Fuzz Face problem

[Craig V]

Yet again, I have a sort of working FF.  I hope someone can see what's wrong.


I measured the voltage on Q2 as C - 2.55, B - 3.4, and E - 2.55.  I used BC109C's for both.  I am positive the caps are reversed and the battery hookup is opposite of the PNP germanium version I have.  The tab coming out of the can of the transistor would mean its the emitter, right?  That's how I have it, BTW.

When I plug in to a guitar and amp, it gives a really wierd sound.  It takes a very hard strum on the Neck pup to get this really farty clip.  

I know the transistor voltages are off, does anyone have any idea why they are off?  Any solutions.

I thank you in advance.  

[R.G.]

Just offhand, the simplest explanation for the collector and emitter being at the same voltage is that they may be shorted together.

[Craig V]

I went through the whole circuit looking for shorts, and found none.  I swapped out the transistors for sockets (something I should have done in the first place) and different transistors, and still got the same readings.  Well, the collector is .01v higher than the emitter now.  I have been looking hard for shorts, do you have any ideas that I wouldn't have thought of?

Thank you very, very much.

[Rob Strand]

Sounds like Q1 is completely off.  Did you reverse the electrolytic cap polarities as well?  - you need to do that if you are working off a PNP ckt.

[Craig V]

Yes I reversed the caps so the neg side is the opposite as the PNP.  I have been messing around with my FF this morning, and I found this:

The fuzz pot, from about 1-8 or 9, produces the same amount of fuzz no matter where it is in this range.  Above this range starts the wierd clip only if you really strike the strings.  I think some people call this the noise gate effect.

I am still getting the E and C of Q2 almost the same, and the B is .6V higher than them.  Shouldn't it be lower than the C?


On a different Ge FF, the fuzz pot works until I get to past 3 oclock, it just cuts out the sound.  Do you think there might be something wrong with these pot or how I wire them?

Thank you all.

[Rob Strand]

All the symtoms you mentioned stem from the fact Q2 is held on - it's kind of cutting the audio out, like a gate in fact.

I think the problem lies with Q1, it appears to be completely off.  You would get this type of behaviour if you are using the wrong pin-out eg. E and C are reversed, or perhaps if any of the leads aren't connecting properly.  Maybe post your Q1 voltages.

[Craig V]

Thanks for replying.


I measured Q1 at C - 3.3V and B - .6V and E is grounded.  I have swapped out the transistors for sockets, and tried a number of NPN transistors.  Those seem off, very off.  Aren't all of the measurements supposed to be under 1V except the collector of Q2?  The battery was at 8.9V.

Just to make absolutely sure, the tab does mean the emitter?  That is how I have them in, but who knows, it might be different for NPN Silicons.

I used the PCB from Fuzz Central, and have gotten a FF working using this design.  

I'm beginning to think that if I can't get a FF right on the first try pedal building might be something beyond me   .


Thank you.

[gez]

Are you sure the collector resistor for Q1 is the right value?  

Don't give up by the way, I'm sure you'll get this one up and running!

gez

[Craig V]

IT'S ALIVE!!!!!!!!!


Here is what was wrong.  I had the 330 and the 33K resistors in the wrong place, not because I read the values wrong, but because I wrote down the placement wrong.  For some reasong I switched them around.  If you look at Fuzz Central, the Silicon board has them the way I had it, but it must have used a different layout than the one I used.  

I'm kind of embarassed it was that. :oops: ..but at least I get to use the cool smiley...

You guys have no idea how much I am in debt to you.  Both of you knew something was wrong in Q1, which turned out to be the voltage applied to it.  This was a big confidence boost in my pedal abilities, and it's time for me to move on to the Octavia.... so be expecting a post in a day or two about that....

It sounds just like it should.  I can't wait to use it at band practice when I can crank the amps.  


Again, thank you very, very much.  Without this board I would have been done with pedal building months ago.  

Have a nice day.

[smallbearelec]

Craig--

Congratulations! I'm glad you're stoked. Now a suggestion: GET a solderless breadboard! You need not buy it from me; Radio Shack and other mail-order vendors carry them as well. You can set up a circuit and make it work, then tweak it till it sounds the way you want it to, all without picking up your iron. It's helpful even when working with well-characterized circuits, and it's absolutely essential when you get into cooking up your own ideas.

Regards
SD