Signal with Effect ON But NO BYPASS Signal??

[analog kid]

I have a strange problem with the MK11 tonebender clone I built. I at first had no effected signal at all but there was bypass, due to a power supply problem (bad ground coming off the input jack), which is not too unusual. However after getting it straightened out I now strangely have effect signal but NOTHING AT ALL when switched into Bypass!!
I've looked and there is NOTHING about this ever being a possible situation in any of the Troubleshooting FAQ here or GEO. So what would be the most possible probability for this?? I'm using one of the Blue 3P switches and it's of course a PNP pos ground crkt.  
Thanks

[R.G.]

It ...might... be a switch wiring problem. Just a guess.

[analog kid]

Just an update on this problem with No Bypassed signal . Whether is pertanent to the problem OR just another problem altogether I don't know. But I only assumed when I got effect signal and it sounded pretty good with the guitar volume up all the way that there was no problem. I found that when I lightly plucked the string and/or cut the volume back the fuzz sounded very mis biased and sputtered. I took voltages on Q1-Q3 and found the ONLY legs with a voltage reading of More than 100mA was the Collector of Q1 and Q3 (both around 7vlts) everything else was 0 - 70mA so there is definitely a problem in the circuit!!

[analog kid]

I got rid of the bypass problem so I do have signal both on and off. But the Fuzz is just really low volume compared to Bypass and sputtery. I still can't find a mistake or miswiring in the circuit . And the transistor voltages as I said are really non existent.
Q1 collector is now the ONLY one that has a Voltage(6.18v) Q1 and Q2 Emitters are at 0.00 And all the rest are right around 50-60mV!!!
Is there anything in particular that will TYPICALLY pull these down to this extent?? I did use an old 47uf Elec.Cap which in this circuit is tied (-) to -9vlt and (+) to Q1 and Q2 Emitters and Protection Diode.  Could it being bad cause this type problem??

[R.G.]

Q1 collector is now the ONLY one that has a Voltage(6.18v) Q1 and Q2 Emitters are at 0.00 And all the rest are right around 50-60mV!!!

Could you provide the info as requested in the sticky "What to do when it doesn't work"?

[analog kid]

Ok I'm sorry Icouldn't locate that Sticky post that had the form to fill but here's the best I could do by memory:
project:  MK11 Tonebender
source for layout /schematic:  Fuzz Central
http://fuzzcentral.tripod.com/benderII.html

type of build: Perfboard design

Substitutions/Deviations from layout: .082uf polystyrene cap in place of .01 Capacitor off of + of .47 input elec.cap.
and 5k fuzz pot

Symptom:  Effect works both in FX on AND Bypass position. But the effected signal is extremely "gated". Only passing signal (Fuzzing) when the strings are attacked a bit harder. If they are just lightly plucked No Sound will come out!! this is Obviously a bias problem but I can't find the cause

voltages:
Battery 7.89 which I know is a bit low but trust me I've tried with the same results with fresher batteries. this just happento be in therenow
Q1:E 0 B 60mV C 6.08v
Q2:E 0 B 48.5mV C 64.2mV
Q3:E 7.29v B 71.4mV C 76mV
these are all showing up positive voltage with the Red meter lead to Ground and Black to Transistor leg, I don't know if they should be Neg in these cases?
and this all shows there to be Obvious trouble with enough Bias getting to BASE but I don't know what is a possible cause. and if there is more to it than that with all the ultra low voltages showing  up. (I would rather see NONE Ithink) So I hope maybe one of you will know exactly where to look! Ihave already tried reversing the protection diode ,it's as it is on the layout. and all caps look to be properly oriented

[petemoore]

I see alot of different PS hookups on the basic TB circuit on that page...
 Just as a rule [for me] I leave the black lead in a black hole of the DMM Red in + or red...
 Then clip the black lead to ground.
 For PNP Pos Gnd, I'd be looking for neg or - Voltage readings...course if the red battery lead is Gnd'd, that's what you'll get...it's the 'intervals' of voltage were looking for...as long as its PNP Pos Gnd and your battery clips red to ground and black to 'up' the - or + you see on the DMM is of no consequence, it's the decimal point and the signifigant figures [digits] you need to look at. Mixing the leads up or the + and - indicators...just look to see above is striaght and they don't matter.
 For the last Q in a FF or TB, the emitter should be a small number, and the collector should be around 1/2v.
 If you socketted, pull Q3 and test Q3's Collector resistor [did you use a trimpot?], that would be Red and Black DMM leads across Q3C Resistor in 200k range reading.
 You can do the same for other resistors, if you see a value lower than a resistors code mark in circuit, look for the alternate current path...then disregard or go figure...might mean some math to figure out whif the low reading makes sense...
 I just go through the circuit in DMM R mode, then DMM continuity [beep mode]...and continue applying that meter every which way I can figure...then compare the readings to the resistances shown on the schem...dogmatic, but it's worked for me...

[analog kid]

I'm sorry I should've specified on the Version of the Tonebender I made. At the bottom of the page where it gives layouts, parts list.etc...
This is the layout design that I used
http://fuzzcentral.tripod.com/benderII/mkIIlayout.gif

And I have went through the circuit with the continuity feature looking at the schematic and everything looks right. I don't know if it could be a wrong resistor value somewhere but I will check those again too.

[petemoore]

Tha'ts a PNP Pos Gnd. MkII TB.
 Red batt lead to Gnd.
 Using PNP [probably Ge...] transistors.
 We know how these things are, when you keep at it, we think you're bound to find it, because it HAS to be there...and couuld be anything...
 I did find a bad tranny during a recent TB build debug...
 I use PNP Si's to 'pre test PNP circuits...
 Relaxing, not drinking coffee for a few hours, then trying to find the new 'angle' on DMM to Board...may help/
 Those voltages are very low, I'd first keep looking at resistances and continuities....
 No Battery, Hook beep moded DMM black to ground, check all grounds as marked on schematic, then check that no ground has gone where ground shouldn't be...poke red probe all over the board
 check that all transistor socket lugs or leads Don't have continuity.

[analog kid]

to Pete. Yes I did use the Trimpot for Q3 Trans. so when I pull Q3 as you said and check the resistance on it's resistor. I just get whatever it happens to be set at (0-20k) and as far as checking all the other transistor resistors.I guess the fact that they goto -9v OR Ground respectively Together on some of them I don't seem to be able to get proper resistance readings for them except for the 470ohm(I get about .486k) and I didn't mention I used a carbon Composition for that.
And as far as applying the meter , poking the Red lead everywhere .. There's only so much I know to look for and have done most of it. That's why I posted for help. If it's not an easy to see problem,Mistake in layout or bad connection/solder, wrong value.... I may not be able to find it. I can check contin. everywhere but for Resistance readings I DON"T know what to look for !!! except on resistors of course OR when looking for Infinite OR Zero resistance. Anything more complex I'm just poking around and reading jibberish.
IF a Ge'  is tested gives good leakage and hfe CAN IT STILL BE BAD???
ONE OTHER Question : Why does it look like on the schematic that the +9v battery goes to the Jack TIP and not the RING with the INPUT going to RING instead. Isn't that what that schematic says? or am I just stupid?

[petemoore]

to Pete. Yes I did use the Trimpot for Q3 Trans. so when I pull Q3 as you said and check the resistance on it's resistor. I just get whatever it happens to be set at (0-20k) and as far as checking all the other transistor resistors.I guess the fact that they goto -9v OR Ground respectively Together on some of them I don't seem to be able to get proper resistance readings for them except for the 470ohm(I get about .486k) and I didn't mention I used a carbon Composition for that.
And as far as applying the meter , poking the Red lead everywhere .. There's only so much I know to look for and have done most of it. That's why I posted for help. If it's not an easy to see problem,Mistake in layout or bad connection/solder, wrong value.... I may not be able to find it. I can check contin. everywhere but for Resistance readings I DON"T know what to look for !!! except on resistors of course OR when looking for Infinite OR Zero resistance. Anything more complex I'm just poking around and reading jibberish.
 >>>If one lead of a resistor is a 'terminus' ... say the only thing one side would connect to would be a transistor, and you pulled that from the socket, then you can measure it in circuit and should get a value reading close to the code marking on the Resistor. Others may need to have one end pulled to measure them [only] and not an alternate current path through the circuit some way...pulling resistors leads from circuit is rather invasive, so I tend to either skip those with an alternate current path [besides through that resistor only] or do ballpark math to figure out why the meter says what it does [always the 'extra' path will cause a lower reading if anything] and if the info it gives bears out as 'good'...nasty technique...filled with gotcha's and exceptions...but I like it. Now if you measure across a resistor in circuit and get a higher reading than what's called out in schema, you'll need to adress that issue...replace with correct value. An alternate current path CANNot cause a higher reading than 'that' resistor.
IF a Ge'  is tested gives good leakage and hfe CAN IT STILL BE BAD???
ONE OTHER Question : Why does it look like on the schematic that the +9v battery goes to the Jack TIP and not the RING with the INPUT going to RING instead. Isn't that what that schematic says? or am I just stupid?

I'll try to get a copy of schem on task bar and then type a bit...

[petemoore]

http://www.generalguitargadgets.com/diagrams/tonebender_m2p_sc_pn.gif
 Here;s the one I just used, to build a PNP pos Gnd TB...should be close to what you have there...compare and contrast...I think maybe only a little cap value change ... probly the same , anyway for kix...
 Take R2 for Ex:
 Pull Q1 and Q2, there IS only one way for DC current to travel [  ]through this reisitor...you should read ~10k on that one
 Same deal for R1...~100k  
 Sans transistors R2, R3 and R6 should read stated values when measured in  circuit
 You might as well add all the resistors to that test, if they don't read about 10% + or - the stated value, then fix it or post the difference.
 Start touching on a black dot ... Node ... with a beep mode DMM lead > touch at all points to connect to that node...say...C1, R1, and Q1 ...for ex: these three components and these three only connect to what I'm gonna call here 'node #1'...repeat this procedure for all the nodes.

[petemoore]

http://www.generalguitargadgets.com/diagrams/tonebender_m2p_sc_pn.gif

[analog kid]

Pete Moore Said:
Take R2 for Ex:  Pull Q1 and Q2, there IS only one way for DC current to travel [ ]through this reisitor...you should read ~10k on that one
same for R1...~100k
ON THIS DO YOU CHECK FOR RESIS. WITH THE CIRCUIT OFF (like normally with resistance) OR ON OR DOES IT MATTER  WITH Q1/2 pulled?

Also I HAVE been doing what you said ( picking one "Node" on the schematic/board and making sure that it connects everything it's supposed to and nothing it shouldn't EVEN INCLUDING the OFF-Board Stuff. ) This doesn't mean that I haven't MISSED the problem though. And I'm sure it doesn't hurt anything to keep going through the crkt back and forth, so I'll try it some more and compare my schematic with this one

NOTE: I have also been using my audio probe On this circuit to find the problem. And before I was ONLY getting audio at all parts connected to the Input cap and maybe just a couple transistor legs. but I'm not sure what I'll get if I run it now. Is there any Particular area YOU would be listening to? going by the info/ readings I've given here?[/quote]

[petemoore]

I like to divide and conquer, I find it's alot easier to find a problem when it's isolated, and so I never mess with jacks 'n switches until I know the board works. Cuts down on worn wire and shorts too.
 Tip almost invariably goes through switch to circuit input [True Bypass].
 If you're reading reasonable voltages then your PS connections are probably correct.

[col]

I had this last weekend. It was due to a faulty switch, and I only found it by checking along the signal path with a multi meter. I fixed it by putting a blob of solder on the offending part which was at the bottom of one of the connecting posts on the bottom of the switch. Now the two parts are bridged it works fine.

[analog kid]

Divide and Conquer huh?? did you explain what this "technique " is to me already?? As far as the No Jacks no switches... I assume you are  verifying the circuit is working properly by ONLY checking Voltages, signal at output,etc... . Well the problem with that is AT this Point i pretty much don't know what to look for along those lines from circuit to circuit to TELL ME that it is working. UNLESS I'm TOLD what to look for! So me actually being able to Hear the circuit and use a meter seems the only way I can go. And I have followed the GGG layout for a 3PDT PNP crkt with Battery only.  Leading me to anohther question:
Does it DEFINITELY mean that there is a Bad Or Wrong connection WITHIN THE CIRCUIT when having a bias problem like this with these ultra low voltages on the emitter and base of the transistors. ??
Or can it be as "col" stated with his prblm. that a Bad switch or jack connection could cause this problem?
i've been over this circuit and offboard stuff over and over (maybe not enough to find a hidden prblm  but enough to ask for some help in where the problem is LIKELY to lie!!)

Also col,  what do you mean that you "had this" problem , was it a fuzz, a tonebender?? and was it the exact same problem?? were you using a DP or 3P switch when you found a bad one.? I believe I've already tried bypassing the switch completely but It is worth trying a different one.

[analog kid]

well I ruled out a bad switch (if that could cause it anyway)  Same thing with a brand new one!
Anyway I've been through the connections and layout of this circuit and I'm stumped. I've still got the Only Voltages on Q1 Collector and Q3 collector / Zero vlt. On Q1 Emitter and Q2 Emitter / And nothing over 75millivolts on every other leg!
So just ASSUMING that there are no mistakes or bad solder joints in the circuits path,  Are there any Particular and if so What Component(s) being Bad would cause this. ??
The only thing strange in there is that the 47uf 16v electrolytic cap is an old used one from a scavanged circuit and for the .1uf cap running to the Q1 collector and 10k resistor is one of the BIG 100vlt Orange Drop type , that I've never used before but I thought I'd seen them in some of the Arbiter F.F.'s            Someone please point me in a Direction!!!!

[analog kid]

well , all this struggling to find what was "wrong " in the circuit. And I remembered someone (maybe Pete) saying that they used a PNP silicon like 3906 when testing their crkts that use Ge's .
So Just to see , I put a 3906 in Q2 and Q3 and of course had to leave the Germanium in Q1 since it won't tolerate anything else in a tonebender.
And What do you know!!??? All of a sudden I am getting "more Normal" voltages on those two transistors
Q2 E -0  B  .600v C 1.2 V
Q3 E  .656   B 1.28 C (5.6V) the trimpot NOW works but won't go any lower than this with the PNP silicon
I plugged in and the FUZZ worked with NO GATED misbiased sound!! of course not very smooth and very harsh sounding

So not understanding what was going on I stuckthe  germs back in and I don't know HOW but even though the Voltages all went back to ultra WEAK the Gated blatty fuzz was gone with them in there too!!!! Though still Not the greatest sounding fuzz but it works and cleans up when the volume knob is cut back.  Though the trimpot WON"T work with the Ge's in there but DOES when replaced with the silicon PNP's! what gives
I should clarify . .  The transistors I used are the AC188's I bought from Jack Orman. They all tested at less than 275uA leakage and Gains respectively  78, 95 and 105.    is the leakage possibly still too high and causing all this problem?!
It's worrying me now what I WILL be able to run in this ( and I don't want to have to buy a matched set from Steve Daniels!) I do have some hfe selected AC128's coming from Banzai electronics.. and some NOS OC75's and AC125's THAT I'd like to be able to select for the circuits I want to use them in!!! Using the Steve Daniels or RGKeen methods . It obviously did me no good on this one though!
what to do with this thing