Transistor Voltages??FUZZ Circuit trouble

[analog kid]

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Ok Here's what I have now with the Multiface from ROG that I started far too long ago and firstly let me say that I appreciate the help I'm getting on this forum!
Bvolt. 8.05v
22uf Cap + = .7v
- = apprx. 2millVolts
Q1 C = 1.5v
B = .67v
E = 0

Q2 C = 5.79v
B = 1.69v
E = .724v

Major improvement from what I had before and ALSO I DO have it "WORKING" in both on and off positions. The big problem is that there's a POP when switch is turned ON but not OFF and the Effect ON Volume is MAJOR HOT  compared to bypassed signal and the Fuzz Control doesn't really affect the fuzz alot (it's just a steady Mild fuzz whether turned up or down)
NOTE: when the volume pot is turned down to about 1-2 the fuzz isn't that bad and the volume is even with the bypass signal . Otherwise it's just WAY LOUD

[R.G.]

Can you help us with the following? It'll go faster.

============================================

The following is a “how-to”, step by step procedure for getting the most help fastest when your newly soldered up effects circuit just doesn’t work. The material is copyright 2005, R.G. Keen, and is displayed on diystompboxes.com by permission. Permission is not granted for redisplay from other web sites without permission in writing from the author.

Gather the things you’ll need
A full set of information about what you built
1.Name of the project: Example: Neovibe, from General Guitar Gadgets.
2.Links to the source of the project â€" web site with the schematic or project, layout and wiring diagram. Example : Neovibe
3.Some candid admissions about how closely you followed the suggested layout, if any. If you just perfboarded it, say that, and if you can, include a picture of the board. Scanners do a GREAT job of making pictures of PCBs, by the way.
4.Any parts substitutions or modifications you made to the original. If you didn’t have any 10uF caps and used 22uF, say that. If you had to use a 2.7K resistor instead of a 2.2K, say that. If you used a BC109 instead of a 2N3904, say that. By the way, if you substituted any transistors, it’s a sure bet that the first question you get asked will be “Did you check the pinout of that transistor?” Delight the questioner by saying (truthfully…) “Yes, I did a google search on that part number and check the pinout against how I soldered it in.” If you can’t say that, chances are good that you’ve already found your problem, all by yourself.
5.Whether or not it’s a positive ground circuit like a PNP fuzz or a Rangemaster that has been hacked to work with negative ground. This is a special case, but a common one. “Positive ground” means that the positive/red lead of the battery clip is connected to signal ground. “Negative ground” means that the negative/black lead of the battery clip is connected to signal ground when the effect is operating.
6.What it does and does not do â€" how it works; partially or not at all. For instance, if it lets no sound through; or if it makes a harsh, distorted sound only when you strum hard on the strings at full volume; or if everything is really, really low volume.

An electronic meter capable of reading 0-20Vdc and with an ohmmeter scale. This can be analog, but digital ones are available for as little as $10.00. I’ve seen them as low as $2.99 here in Austin Texas in 2005. If you have to, borrow one. There is really very little anyone can tell you that would help if you can’t measure and tell them what voltages you get. It will be much easier if your meter has some way to clip the negative/black lead to circuit ground instead of having both leads with only points. Most meters do. If yours doesn’t, you could use a clip lead to do this, if you have a clip lead. Here’s a quick guide to how to use a meter in simple laymans’ terms. (to be added â€" RGK)

A non-dead battery. Measure the battery with the voltmeter. If it’s not over 8.0V, it’s going to gum things up and give you inconsistent results. Get a fresh one. Using a DC wall wart is problematical. What if it’s the wall wart that’s bad? Get a good battery.

A calm, open mind. I don’t like to admit this in open company, but one of the deepest episodes of rage I ever felt was when I had been flogging this one poor circuit board to death and even though all the hookup wires and parts were in the right place, nothing worked â€" for hours. I was almost speechlessly angry â€" until I noticed that I was debugging the bottom side of the board for access to all the solder points and had neglected to put the ICs in the sockets. The madder I got, the LESS capable I was of noticing the real problem. You gotta clear your head first.
Being absolutely certain that everything is correct and it still won’t work is not good preparation for noticing an errant solder thread, for instance. Mother Nature does not lie, but she is a stickler for details. If it was put together perfectly, it would work. It not working is Mother Nature's way of telling you that you made some tiny error, and it's no reflection on you if it's not perfect the first time.

When you have everything gathered, but before posting, get the specific information you’ll report.
1.Hook up the DC power to the circuit (no input signal or amp needed) and clip the meter black/negative lead to signal ground. Probe **every** pin of each IC, transistor and zener diode (if any), and also the battery at the clip and where the battery wires come onto the board. Make a written list of the voltages. Below is a helpful starter list of the minimum things to measure.
2.For extra credit â€" search the forum archives for problems with the same circuit. Someone else may have had exactly the same problem.

(d) Now post. Post all of your gathered information along with the list of voltages along with a request for help interpreting them. Chances are, someone will spot the section that’s not running correctly right away. Then a few more secondary tests will likely have it nailed. You’ll be posting it to a forum where most of the people there will have been through exactly the same situation. They want you to be successful, and they don’t think you’re stupid or not cool for having a problem with it.

(e) Learn. There are certain things that always determine what's working and what's not. Read the postings of others that have posted their voltages and find out what happened to them. That way, you get the benefit without having to make the mistakes. Search the archives for problems with the same circuit. Read the debugging page for the indicators about what voltages indicate about function. This last takes a long time, but it's the most rewarding. If I had had a similar forum to learn debugging in when I started this, I’d have wasted a LOT less time in my life.


That’s the procedure.

Here is the checklist to fill out:
1.What does it do, not do, and sound like?
2.Name of the circuit =
3.Source of the circuit (URL of schematic or project) =
4.Any modifications to the circuit? Y or N
5.Any parts substitutions? If yes, list them.
6.Positive ground to negative ground conversion? Y or N
7.Turn your meter on, set it to the 10V or 20V scale. Remove the battery from the battery clip. Probe the battery terminals with the meter leads before putting it in the clip. What is the out of circuit battery voltage? =>
Now insert the battery into the clip. If your effect is wired so that a plug must be in the input or output jack to turn the battery power on, insert one end of a cord into that jack. Connect the negative/black meter lead to signal ground by clipping the negative/black lead to the outer sleeve of the input or output jack, whichever does not have a plug in it. With the negative lead on signal ground, measure the following:
Voltage at the circuit board end of the red battery lead =
Voltage at the circuit board end of the black battery lead =

Now, using the original schematic as a reference for which part is which (that is, which transistor is Q1, Q2, etc. and which IC is IC1, IC2, C1, and so on) measure and list the voltage on each pin of every transistor and IC. Just keep the black lead on ground, and touch the pointed end of the red probe to each one in turn. Report the voltages as follows:

Q1
C =
B =
E =

Q2
C=
B=
E=

IC1 (or U1)
P1
P2
P3
.
.
.

D1
A (anode, the non-band end) =
K (cathode, the banded end) =

D2
A =
K =

Z1 (zener)
A =
K =

And so on until you get through them all. Having gathered the data, post a tidy list of it on the forum, and you’ll most likely have a working effect soon.

For extra credit, while you’re waiting for someone to tell you what they see, probe the pins of each of the electrolytic caps, verifying that the voltage on the (+) pin is more positive than the voltage on the (-) pin. If it’s not, that cap will eventually fail, whether it’s the immediate cause of the thing not working or not.

Yes, it is a pain. But it is a time tested, effective, highly productive pain.

[analog kid]

thanks for that instuction sheet , although I don't know what else there is to tell you besides this:  (I've already gave the only reading there are to take to start with at least and I'd have given the site and effect name had I not figured that EVERYONE here had probably already built one or at least seen it)
  1>  Multiface   fuzz face circuit
 
  2>  Runoffgroove   http://www.runoffgroove.com/multiface.html
 
  3>  I did the project on perfboard with a circuit writer pen and ALL circuit components are AS described .  The layout I used IS the one on the page of the link above. NOT the PDF link layout that's given
 Except that some things ( the Pots for Volume and Gain) did not list values at all so I used the norm which I thought  to be a 100k for Volume and 10k instead of 5k (lowest I had) for the Gain/ Fuzz control
Also the Transistors used here are various as you can see , several are used for different effect and I have Q1 and Q2 socketed as well as the Output cap (I ran out of sckts) SO.. I have tried several diff transistors ie; 2369's, 2N2222's , BC109c, 2N3904 etc.... And YES I've paid close attention to the pinout.
 4> The signal is present both ON and IN bypassed. as I said earlier the ON signal is MUCH MUCH louder than the bypassed and the volume pot has to be turned down all the way to about 1-2 to get it even with the straight signal . The FUZZ IS present but the Gain/fuzz pot does NOTHING to affect it .

The measurements I got are current , taken with the power connected and I will list them again:
Battery volt. 8.05v
22uf Cap + = .7v
             - = apprx. 2millVolts
Q1 C = 1.5v
    B = .67v
    E = 0

Q2 C = 5.79v
    B = 1.69v
    E = .724v

[analog kid]

Forgive me for getting anyone on the wrong troubleshooting road for this problem but I double checked the transistors orientation and had one turned backwards( been working on 2 projects with reverse layouts)
This thing IS fuzzing , the volume when turned up very much is STILL Way Loud! The FUZZ control IS affecting the fuzz but gets most of its 'major' gain at the last one notch HOWEVER>.........
there MUST be a problem with my trimpot , which by the way IS a 20k rather than 10k I forgot to point that out. What I noticed is , and I don't think this is normal , is that the trimpot is adjusting my Q2 Collector between .6 and 6.6volts then for some reason ALSO is affecting my Q2 EMITTER from 0v to 2.5v  and  Q2 Base from .68 to 1.3v
And  Q1's BASE from 0v to .641 ANNNDDDDD!! the Q1 Collector from .6v to 1.3 vlts  
WHY IS THIS HAPPENING ,or am I just crazy thinking this isn't normal ? I didn't notice it on my other fuzz circuit.
I also JUST noticed that the Volume pot is tapering BACKWARDS and although the Fuzz pot is 'fuzzing' harder when turned all the way up  it brings on a "Transistor Squeal ' if you know what I mean , at the end of the FULL gain taper.
 take your time but HELP is greatly appreciated

[petemoore]

Forgive me for getting anyone on the wrong troubleshooting road for this problem but I double checked the transistors orientation and had one turned backwards( been working on 2 projects with reverse layouts)
This thing IS fuzzing , the volume when turned up very much is STILL Way Loud! The FUZZ control IS affecting the fuzz but gets most of its 'major' gain at the last one notch HOWEVER>.........
there MUST be a problem with my trimpot , which by the way IS a 20k rather than 10k I forgot to point that out. What I noticed is , and I don't think this is normal , is that the trimpot is adjusting my Q2 Collector between .6 and 6.6volts then for some reason ALSO is affecting my Q2 EMITTER from 0v to 2.5v  and  Q2 Base from .68 to 1.3v
And  Q1's BASE from 0v to .641 ANNNDDDDD!! the Q1 Collector from .6v to 1.3 vlts  
 Using a 10k gain pot'll do that...
 20k trim should be fine for Q2 collector, just set it for around 1/2 supply Voltage. The bias of Q2 with 5.79V at the collector looks good to me...
WHY IS THIS HAPPENING ,or am I just crazy thinking this isn't normal ? I didn't notice it on my other fuzz circuit.
I also JUST noticed that the Volume pot is tapering BACKWARDS and although the Fuzz pot is 'fuzzing' harder when turned all the way up  it brings on a "Transistor Squeal ' if you know what I mean , at the end of the FULL gain taper.
 If you want the Volume control to work inversly, invert the pots lug 1 and 3 connections.
 You're using a 10k gain pot, squeal is on Par I think.
 take your time but HELP is greatly appreciated

...so....it Fuzzes, boosts, and both pots are doing something....sounds like it's working to me, but I'd try to see about getting some pot or pot circuit around 1k-2k2 range for the gain pot....heck for fun, try a 2k2 across the 10k gain pot you have...should work with better taper that way anyway...I think the gainpot is supposed to be linear,...but worth checking that before ordering...

[analog kid]

Yes  Pete I know what you mean, I would say its working too .. Even with the HUGE volume difference and all IF IT WEREN"T FOR that the FUZZ / Gain pot (which I  have already altered the value of by placing a 10k resistor on it before your last post I guess we're on the same page there, It brought it to just under 5k ) anyway it's giving just an awful " like touching transistors" squealing  when you max to full. Where usually your best sounding fuzz in a fuzzface circuit IS!!  SO SOMETHING has to still be wrong somewhere
So that's normal for the trimpot to affect ALL of those different Transistor Legs in this particular crkt??

[Ivana]

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...
Q1 C = 1.5v
...
Q2 B = 1.69v

Yes, it is a big problem!!!  :lol:  :lol:  :wink:

[analog kid]

OK? Could you (or anyone) elaborate on that? WHY that's bad , if it is.. then what could POSSIBLY be the problem? And What should my target voltages be ?   I still haven't got an answer on whether or not it's normal for 4 of my 6 transistor voltages to be affected by my trimming the bias pot that I thought was there for Q2 Collector.
  Also those vltgs were before I biased that to 4.5v apprx.
They are now:  Q1 Collector  1.28v
                       Q2 Base  1.3v
Still not good I suspect?

[petemoore]

First what is a circuit pen.
 Second the 22uf '-' pole is supposed to be at 'exactly' ground...if you're reading a voltage potential FROM ground to where ground is suposed to be there's a problem.
 Third I think Ivana is pointing out that Q1C and Q2B Are to be Connected, [looks like a good 'catch'] reading anything but continuity between these points, or any voltage potential differences is also a Problem.
 I'm suspecting cold solder may be a culprit here 'n there.

[analog kid]

Ok first .. A Circuit WRITER , ya know a circuit writing Pen with conductive ink for drawing circuit traces! It's alot easier and quicker to use when working on this perfboard than tieing components together with leads and such. I mean it dries to PURE continuity so I wouldn't point to that for the problems. which should also rule out the cold joints but I didn't use it everywhere so There may me one.]
Second ,  The Q1 c  and Q2 B Are tied together as they should be (if you read back you see that I took that reading before I realized that I DIDN"T have them connected. the problem has changed since then)And they BOTH show EXACTLY 1.20 Volts
Third  I guess what you meant about the 22uf cap POLE tied to ground was that the NEG of it is at ground. WHICH IT IS since I thought I said but might not have, that the + side reads .784v and the - is 0 volts or like .001 millv

THE Problem with this thing is just the HUGE volume where the POT has to be at about 1 or 2 to be even with bypass. Anything after is Speaker Blowing! AND that the FUZZ pot can't be turned to full do to a horrible sputtering sound like Transistors being touched from underside of the board.   If you move the pot or the leads to the FUZZ pot it will cut out sometimes but I can't find the short!!!

[petemoore]

Well all the reviews I've read about circuit writer [yours is the only]...I'll stick to soldering parts...let me know how that goes, sounds like it's easier to use than soldering parts.
 Have you used the 'writer' for other projects ?
 I don't know where the continuity checker draws the line for low resistance to equal a continuity beep, but does the Dmm beep when you go from ground to - on the polarized cap?

[analog kid]

Yes I have used the crkt pen for other projects and trace repairs (it's uses on the package do show Making Prototype circuit boards) NO problems
and yes it BEEPS when I go from NEG (22 Cap ) to Ground BUT I NEVER "JUST" check for the cont.beep when looking for a connection , I also Set to RESISTANCE and Make sure I get as close to 0ohms as possible which I notice sometimes I'll get as high as .4 ohms with some of the traces it makes but I'm sure that 's from me not making a good, heavy enough trace with it. (and yes it'll still beep, but up to what I don't know either)
PLEASE GO TO my post about HELP with USING the AUDIO PROBE. I used the example of my trying the one I made, on the Muliface that we're trying to figure out and as I explained there , I've found someting VERY INTERESTING that may lead to the culprit of the Freaky Deaky Squeal!
http://diystompboxes.com/sboxforum/viewtopic.php?p=201058

[Triffid]

Hi, i would try 2 things in this order...

1. get the q1 c voltage down to about .5 volts..  Do this by altering the "33k ohm" resister into the collector.  Bias your q2 c down to 4.5 volts by altering the 8.2k ohm" resister.  

if that doesn't work

2. alter the c "470 ohm" resister to try to lower the volume.


If those don't work, get a hold of some better transistors, from small bear or something

[petemoore]

Ok you've got a beep at ground...that's what I use to satisfy myself for ground.
 I don't know where the meter stops beeping resistance wise, I've never had a problem after getting beeps from all grounds, if that's any consolation, I think grounds are made when the meter beeps on 'em.
 The gain pot affects gain as do the transistors and other matters mentioned in post above this. Squealing FF's are not uncommon.
 What type of trannies are you using?
 Cool thing about the MF is you can try different tranny's and bias them easily, but some added voiceing may also help matters. If you have enough high end, a little HF rolloff may not reduce it more than you want, and allow higher gain settings to occur without it 'actin' funny.
 two places you might want to try rolling off highs a touch...
 Something like or bigger than a .001uf from inside the input cap to ground.
 Similar sized cap from Q2 base to Q2 collector, or collector to ground.
 I found 2n2369 to be very well behaved in Q1 position, Q2...Si NPN like 2n3904, BC xxx...Hfe's of the Q's make it work different.

[analog kid]

All good ideas
Here's an update on what I'm getting using the probe and tell me if it's normal:
 when I leave the volumes at a level that doesn't bring on the 'squeal'>
(and one more time to clarify THIS IS NOT a Feedback/Gain Squeal! it's a high pitched electrical "sputtering transistor" type noise
 I get the effected signal throught the probe amp when touching  the OUTPUT cap, Q2 Emitter, Collector and Base  , and Q1 ONLY the Collector
  notice NO SIGNAL at all from the INPUT Cap , Q1 Emitter AND Base,  22uf cap + or -  OR the +9v area , which may be norm.
           DOES THIS OPEN ANY EYES OR EARS to ANY POSSIBLE CAUSES?

[analog kid]

Sorry  but  on my probing results I went back and tried it again turning up past the NOISE point and found that there IS in fact A SIGNAL albeit a very LOW signal at the +9volt, Input Cap, Q1 BASE , and that side of the R3 100k resistor , as well as the 22uf cap + side. The signal is so low though that the amp had to be cranked AND the volume pot which is super loud when up anyway!  Making Probing the previous areas that had signal almost impossible w/o blowing up a speaker.
   Just thought this would be important
OH , BTW(In case RG is looking) this project is done on perfboard !!

[analog kid]

Ok I have this working well enough at least except for the terrible vol problem (not being able to turn the v. pot to more than 3 w/o a feakin Meltdown!) and the weird noise is not there now as long as i keep that volume there around the same as the bypass signal or a bit more , EVEN IF the Fuzz pot is maxed out. Like it should be able to be!! that was my biggest problem.
However it was suggested to me (by Triffid I believe it was) to try to get the Q1 C down to around .5 v  by adjusting the 33k (100k?) RESISTOR
Is this really a good idea , or recommended Since the rule of thumb for Silicon 'trans. is that the Base should be AT LEAST .5v higher than the Emitter And for the Collector to be 1Volt or more higher than the BASE.
If this is true then this doesnt sound smart to get the COLLECTOR down to a half a volt! that would be putting the Base down extremely low , definitely not leaving room for it to be .4 to .7v above emitter.

[petemoore]

Well maybe in your application this would make difference enough.
When I trimpotted Q1C on FF's, I think around 10k or something the transistor began 'not functioning' well. IME anything between 33k and 100k sould work pretty good...IME. I have no qualms about which I use...47k, 39k, 33k there..whatever value catches my eye first actually.

[analog kid]

I'm sorry but were you referring to the 100k resistor that's between +9v and the Q1 collector , that you replaced with a 10k trim?? I was just making sure it wasn't a mistype that you reffered to the 10k trimpot that's on the Q2 emitter and biases the Q2 collector.  because I've never heard of a trimpot being put on any other transistor leg?

IME anything between 33k and 100k sould work pretty good...IME. I have no qualms about which I use...47k, 39k, 33k there..whatever value catches my eye first actually.

SO are you talking about a trimpot value here or a resistor?? and where ?

If I could find a way to change the way that volume pot is " behaving" it would totally solve the problem. From 3-10 it's totally unusable and THAT"S what brings on that horrible tranny squealing I think. Once I strarted keeping the volume of the effect rather even w/ the bypassed, it never did it even when the fuzz was full on.
I assume that just changing the value of the vol.pot would bring down the amount of gain that it allows during rotation.  What would do that!