ARBITOR FUZZFACE!!!! Help needed.

[fuzzchuff]

yup its me agian i cant get this damn thing working! The fuzz pot on my fuzz face doesnt change the fuzz level ive swapped out the pot for a different one and that didnt fix it. Im using ge transistors/and the resistor values given from smallbear their are no solder bridges or anything its very clean
ives checked the grounds and all the wireing a zillion times im out of ideas with this thing. Cry

q2
c2.10
b10
e0

q1
c2.76
b1.68
e.45

hese the shcematics i used
http://fuzzcentral.tripod.com/fuzzface.html

[guitar_199]

Okay,  I'll give this a stab..... but be sure that you understand....  I am going to be asking some simple questions and it is not my intent to be insulting.... I am going back to the very basics and starting all over again.

First, you reference that particular schematic and it is about as good a reference if not the best of any.

1) You do mention Ge transistors..... are they for CERTAIN PNPs? Can you goive the number.
2) Are you setting it up for positive ground like the original?
3) Where are you placing the black lead for you measurements?

The reason I am starting here is that, the voltages you report at the top indicate a couple of things...

a)  Q2 emitter = 0 volts...... that thing isn't biased up at all.  It is flat "not" turned on.

b) All of your voltages are shown as positive.  If this is a positive ground circuit andyour black lead is fo sure on ground.... the voltages should be negative.  I realize that this MIGHT just be an oversight in writing down the voltages, but it is important, because....lets look a bit closer at Q2.  Q2 E is 0v.Q2 B is +10 volts.  If I accept those two values and that Q2 is a PNP..... that B-E junction is biased HARD off and THAT is a problem.   On the other hand..... if the voltages actually negative then you have a -10 v reading from the B-E of a PNP transistor and that can't happen unless that junction is completely open....or at least that is how it looks to me.

Therefore the first thing I'd like to do is a) verify that the transistors ARE what you believe them to be/what they SHOULD be, then, b) that the battery is hooked up correctly in terms of polarity.

Next did you socket your transistors or solder them in ?  If they are socketed, perhaps we could pull them and make some resistance measurements with you meter just to verify electrically speaking that the PCB is behaving the way it should and that the pots are behaving the way they should, particularly that fuzz pot since it is crucial to the biasing of Q2.

Ride with me a ways, and I bet you'll be posting "success" pretty soon!!!!  That is y goal!

Nothing on earth feels better.

Bob

[petemoore]

  Q2 B and Q1 C need to be connected.

[guitar_199]

Looking closer..... I'll bet your Q2 and Q1 are reversed in your voltage list.

Q1's emitter should read 0v because it is grounded!

But even so there is still a problem because , assuming the following...

Q1 C = 2.10v
     B = 10v
     E = 0v

The B-E is reverse biased to the tune of 10 volts, there should be no current flow through the transistor there fore the collector should be full batter voltage.  Also.... if this is pos gnd, the voltages should be negative.....but if they are.... again.... the B-E junction is forward biased to the tune of 10v and that does not bode well for your Q1 transistor.

Also....

assuming that

Q2   C = 2.76
       B = 1.68
       E = .45

The first thing I notice here is that, Q1-C and Q2-B are tied together directly by copper....they should show the exact same voltage ....but they don't.  Same thing here goes for the polarity of the voltages.  If these really are positive.... then Q2 is biased OFF by 1.2v which should have the transistor OFF and the collector should be measuring full battery voltage.

Think about these few things, maybe re-check your voltages  ( again.....tell me where you are putting the black lead from your meter.... to do these measurements!), and get me the info on the transistors.

[fuzzchuff]

here is the transistors i used along with the values sent to me:
Transistor Pair - The Fuzz Face PNP
http://www.smallbearelec.com/Categories.bok?category=Germanium+Transistors
to test the voltage of the transistors im puting the black probe on ground and touching the pos. probe to trasistors pins, the pins are solderd to the pcb here are my new readings it should say - becouse it pos ground right? im also a newb at electronics, so my questions may seem stupid.thanks for all your replys.

vs. 8.77v

q1
e 0, but sometimes 6.32 i tried wiggling some wire around to see if one was loose.
b -.10
c -.98

q2
e -.47
b -1.06
c  -2.58

petemoor, your saying my q2 tranasistor should be tunred around? becouse its emiter is connected to the base of q1

[guitar_199]

When you are making an earnest attempt to "learn by doing" nothing is considered stupid.  I've worked in electronics/computers since 1977 and you see the "basics" I am going back to!!  Okay.....let's go!

1) those are the same transistors that I have in mine.....bought from exactly the same place.  So we are talking PNP Ge, although I don't know exactly what gains yours are.

2) yep, pos ground.  So your black lead COULD go on the red wire from the batter clip, the emitter of Q1, or the bottom of the FUZZ pot which should be wired back to the same ground point....... not to black battery .... but to red since that is groung.  Don't laugh.... I saw it done...... on MINE!!!!!!!!!!!

3) when you scour the web for info on Fuzz Faces, one of the most oft suggested mods is to replace the 8.2K  resistor in the Q2 collector with a 10K trimpot and adjust this trimpot until Q2-Collector is at about half of the battery voltage.  Did you, by any chance do that? Or are you working strictly with fixed resistors?  Steve sent me my transistors with suggested values as well, but I just opted to stick with the standard circuit EXCEPT for the 10K trimpot.  It worked just like the "infamous THEY" said.  I hooked it up and tweaked the pot, and walked it right to 4.55 volts.  It made all the diff on mine.

4) one thing you brought up concerns me...... that "glitchy Q1-E reading that you got that would be 0v sometimes..... and -6.32 others. That one really bothers me because that emitter should be tied to hard ground.  And the "glitch" would make me think that the ground on that transistor and MAYBE the whole FF may have a problem.  And, see, if the bottom of that Fuzz pot is NOT getting good ground..... MORE importantly, the capacitor, then you wont see any effect when you turn the pot.  The pot is not being used as a variable resistance...at least not in the conventional sense....not for DC.   The pot is a 1K  and ties the emitter to ground.  The wiper is tied to ground through a polarized electrolytic cap.  (be SURE that the  - sign on that cap is soldered to the wiper and the + end to ground.  Electros do wierd things when reversed.  So, if the cap is doing its job correctly, rotation of the Fuzz pot will NOT change the voltage at the Q2-emitter.  TRY THAT!   Meter black to gnd, red to Q2-emitter, and sweep the fuzz pot.   The voltage should not change.  If it does, I would think the 20uF cap is either backwards, or shorted.

If that doesn't show anything,  I would examine the off-board wiring REAL well.  Like I said, when I did mine, my "standard audion thinking brain" said......."GROUND is BLACK!!!!!     Well.....no it aint.  Not in this case.  My fuzz pot  pot was tied back to the battery and it was pretty bizarre.

So I would next make sure that.....

1) the red battery lead, the bottom of the Fuzz pot, the +side of the 20uF cap, and the bottom of the volume pot, and the emitter of Q1 are all tied together AND to nothing else.  Look for solid wiring at each point.   Remember, that "glitch" on the voltage of Q1-E is a problem!   It should be solid ground. always and ever.  While in the area, make double sure that the 20uF cap is soldered in with the minus to the wiper of the fuzz pot and the plus is soldered to the ground group.

2) the black battery lead should go to the junction of the 33K and the 470 ohm resistors.....and nowhere else.

3) if you haven't put a trimpot ( 10K ohm ) in place of the 8.2K resistor, I would think about it.
  This makes the circuit a little more tolerant of transistors that arent right dead on the money.  And if you know ge transistors....THAT describes pretty much all of em.



(one more note on that ground glitch!!!!      if you can make it do it on the Q1 emitter again...... check the other ground points at the same time.  ( bottom of fuzz pot, bottom of 20uF cap,  bottom of volume pot.  The red wire from the battery clip is supposed to be your hard ground.  If the other points are spiking to -6.32v, then something is loose causing them to do it.......  if it is just one thing, or if several of those points do it.... it might give you a clue as to where the problem is..... and I'm betting this is it!)

Good luck!

[fuzzchuff]

ok...
#1 check
#2 check
#3 i didnt do the trim pot thing, the first fuzzface i made i used the original values for the resistors and my transistors were mis-biased. my pedal didint work at all,  so i used the values from smallbeal and it worked great, so i just did the same thing for this pedal.
#4 the voltage at the Q2-emitter does not change when i move the fuzz pot. i also re-solderd the grounds to make sure they were good.
ive  also checked all the offboard wireing/ rewired the whole thing then after that didint fix it i checked all the wireing agian..few..
"the red battery lead, the bottom of the Fuzz pot, the +side of the 20uF cap, and the bottom of the volume pot, and the emitter of Q1 are all tied together AND to nothing else".
im gonna go through all this agian for the millionth time im missing somthing 

[guitar_199]

Trust me, amigo, I understand the frustration.....because I have been here many times.

One other thing that might be interesting........  black meter lead to ground.....red meter lead to the wiper terminal of the fuzz pot.    Move the fuzz pot....  ThAT voltage SHOULD vary..... from ground to the minus voltage found at Q2 emitter.

Be double sure the transistors are soldered in good...particularly Q1.

THat -6.32 v jump on Q1 emitter seriously bothers me......

Out of curiosity....... do you have .... or have access to.... a digital camera...where you could shoot a good close up pic front ond back.....  both sides of PCB and all wiring visible...and post it here???   Just a thought....

[fuzzchuff]

yes ill put up some pics, but it wont be tonight becouse i have to charge the bateries 

[petemoore]

#4 the voltage at the Q2-emitter does not change when i move the fuzz pot. i also re-solderd the grounds to make sure they were good. 
  It looks like fixed resistance to me, the connection between Q2E/100k and ground always goes through the potwafer [lugs 3 and 1] so should be whatever the pot value measures, unless I'm misreading, it's late.

[fuzzchuff]

i swaped out all the caps one by one with the caps of a working fuzz, it still has the same problem so im gonna rule out any of the caps being bad
here are some pics i got to take better ones of the wireing

[fuzzchuff]

quick question cuz im a litte confused. becouse this is a + ground circuit the -9v(pin4 on the curcuit board schimatic) would go to the +pin on the ac jack, along with the black battery wire. now the + red battery wire would go to the -pin on the ac jack,and that 3rd pin on the ac jack would have a wire going to the input jack sleeve. correct? becouse i have the working pedal wired the oposite and it works, but that would mean that my pnp pedal is running on - ground power,and its working! are my making any sence

[fuzzchuff]

now i found diagrams for pnp, negetive ground, and pnp negative ground, whats up with this wich do i use? right now i have it wired to pos. grnd.
ive used different pots, caps, pcb's, wiring diagrams, and i still have the same prob so the only thing left are the transistors could they be cause of this problem?

[petemoore]

now i found diagrams for pnp, negetive ground, and pnp negative ground, whats up with this wich do i use? right now i have it wired to pos. grnd.
  If you're using PNP Ge' transistors, use a PNP Pos Gnd. circuit, like the first one near top of page at Fuzzcentrals FF page.

[fuzzchuff]

ok its all setup for pos.grnd, would somthin wronge with the transistors cause my fuzz pot not to work, the setting its stuck on sounds real good i just cant change it. ive swapped out every part in the thing except for the transistors.

[guitar_199]

Hey, FC.......

Sorry I've been absent a bit.....



I just wanted to focus attention on a couple of areas.  Bear in mind..... the photos were a little on the fuzzy side and, while they did provide a rough look it was not possible at least for me... to follow the wiring from the PCB to the off board components.  If your cam has a MACRO setting...that is great for these.....

In any event.... addressing the areas one by one....


A)     this is the area where the fuzz pot wires in.  The top pointer should get wired to the top of the fuzz pot.  The next one down (should be the PCB trace to the MINUS side of the fuzz pot cap) should be wired to the wiper of the fuzz pot.   The bottom point actually ties 2 or 3 things together.... offboard, one pad should go to the bottom of the fuzz pot, the other should go to the red lead from the battery snap on. Just inside the edge pads is a component pad that should be the positive side of the fuzz pot cap.  Then...a trace goes over to the emitter of Q1 directly.   The last section described here is the entire ground network on the PCB.

(note: I should have marked it but didnt.... the pad right under the top one (that goes to the top of the fuzz pot) should get the black lead from the battery clip.  Now, I must say, I did not use a power jack on mine since, on FF, I prefer a battery.  The inclusion of one has to be done with care.  I will presume that....but it might be good to double check...

B)   I can't be certain from the pic as it is a little fuzzy.... but this point looks like it could be a bridge.... but maybe not.  If it isn't...good.  If it is.... it needs to go.  I included the PCB artwork just for reference.

C)  This one bears a close look.  It has been mentioned a couple of times by Pete, I believe.......      Q1 collector.... and Q2 base.... are tied together by a copper trace.  Yet, each time you have sent voltages...... the two are different voltages.  The last time you reported.... Q1-C was -0.98v    and Q2-B was -1.06.   On one hand you might look at the  difference as negligible but in my experience, it looks like it could be a problem.     At the least..... there might be something coating the joints that is affecting your measurement.  But they really should be identical.

Another couple of things that draw my attention in this area.....

Q2-b = -1.06v    and Q2-e = -.47.   That leaves a Vbe of -.59.    That sure looks silicon......

Q2-c = -2.58v.    In the little experience I have had,FFs just don't act right until they are biased correctly.....and for me... that has been closer to 1/2 the battery voltage.  Mine was way off in this direction once and I literally wound up so frustrated I made a NEW PCB,  re-worked to include that 10K trimpot, rebuilt it. tweaked the trimmer for about -4.7v on the Q2-c and it worked great.  The particular problems I hade were...... too trebly.....and it would NOT clean up.  YMMV....but you might want to spend some time in this direction.

D)    I point this gound net out because.... you mentioned that your Q1-e voltage was usually ground...but jumped to -6.32 v at times.   This really makes me itch.... given that it is a short copper trace from Q1-e to where the ground (battery red wire) attaches to the board.  I think you want to get to the bottom of this one too.


Just throwing it in there......  one of your pics shows the top of the board and the transistors.  Usually the tab is directly over the emitter.....but in your pic.... I just cant tell whether or not the tab is positioned where the emitter should be.  I'd ask that you just re-insure yourself of the pinout of your trannies and that they are in the holes correctly.

If nothing here pans out...... if you can....check to see if the camera you are using does have a macro feature.  I love mine.  It lets you get within a foot of the board and shoot a crystal clear pic.   If you can, a couple that clearly show the PCB edge where the wires are soldered ( top and bottom), the wiring to the pots and the wiring to the power jack might help us move along.