One Knob Tonebender help please?

[somasix]

After carefully following the One Knob Tonebender tutorial in Dragonfly's Veroboard Gallery, it doesn't work.  When the effect is bypassed (via a 3DPT switch) the guitar sound comes through loud and clear, but there isn't the slightest glimmer of fuzz (or any sound actually) when switched on, not even when I try to complete circuit with my body. 

I have a working DMM, but I don't know how to use it and it didn't come with a manual.  I took a cautious month with this project, invested in a new soldering iron, bought better quality parts, and learned an enormous amount in the last four months and I have still failed on three out of four projects.

Does anyone have any idea how to debug this very simple circuit?  I feel like I've fallen into the pit of despair along the learning curve.

[petemoore]

  Read and follow the instruction in the thread "What to do when it doesn't work", and apply it.
  Test for battery Voltage, note it.
  Test for *NoN-continuity between circuits battery clip..or V+/V- [red and black]. If the meter buzzes you'll need to find the short, otherwise connect battery.
  Then Clip or connect black DMM lead to ground of circuit.
  Touch the red probe to each transistors C, B, and E pins, noting each voltage measurement [difference to ground, which is 0 V.].
   Post the voltages and everything else called out in the "WTDWIDW" post.

[somasix]

Thanks Pete.

So, I metered all the various components with my red wand on + and got the following readings:

1M = 4.42
.1u = 4.42
150K = 8.17
100u = 8.79 on the negative side and 0.00 on the positive
220p = 7.48
1k = 8.17
10K = 0.00
Q 1 (BC 109) = 7.48
820K = 0.00
10u = 8.17
2K2 = 8.12
Q2 (BC 108) = 8.16
220 u = 8.13
Center lug of pot = 5.90

Because of my own inexperience, I'm not entirely sure which of the posts on the transistors is C,B, and E.  There was not schematic provided with the tutorial, just the stripboard layout.  Nonetheless, here are my speculative readings for the transistors.  These could very well be backwards.  (These were taken with the black wand on the ground and the red on the legs of the transistors.)

BC 109
C = 0.00
B = 0.54
E = 0.61

BC 108
C = 0.73
B = 0.70
E = 0.61

I noticed a bad solder joint on the 10K and redid it.  Although the fuzz did not come through, I got a signal with the effect on.  When I dug into my guitar, a crackle worked its way into my signal.  There don't seem to be any other glaringly sloppy solders visible, but I'm going to give a couple pads a touch.  Any perspective on the above readings?  Thanks.

Jason

[petemoore]

  Gnd is Gnd whether it is a Pos Gnd or Neg Gnd.
  First thing is show whether it is a Pos Gnd or Neg Gnd Build you're attempting, and that the appropriate transistor type [npn or pnp] is to be used.
  Second is to get a data sheet on the transistor you're using to determine it's pinout [which is C,B and E.
  The transistors pinouts have to match the connections shown for each transistor pin on the schematic. recheck pinout...
  then retake the voltages.
  The voltages you've shown aren't within the operational limits, Q pinouts are a common miswire, did you socket the transistors?

[somasix]

I got the data sheets for the BC 108 and BC 109.  It says that they are NPN transistors.  It's measurements are as follows:

BC 109
E = 0.00
B = 0.54
C = 1.30

BC 108
E = 0.61
B = 1.30
C = 0.61

Testing with the red wand on the + of the 9v and the black wand on the leads of the transistors:

BC 109
E = 7.56
B = 6.86
C = 7.42

BC 108
E = 6.80
B = 6.20
C = 7.44

I did not use sockets, but each of the transistors are placed with the emitters facing as per the tutorial directions and a heat sink was used on the leads to redirect direct heat away from the transistors while soldering. 

[petemoore]

  I find myself reading through lots of 'stuff' and still wondering if I missed what exact circuit you're building.
  Because there may be a language barrier, and we're trying to sort that out at the same time, a link to the schematic is much needed, Imo.
  please indicate which readings correspond to which transistor ... Q1 and Q2.
  Include the measured battery voltage.
 
 

[somasix]

Here's the link to the One Knob Tonebender tutorial.

http://aronnelson.com/gallery/album21

The transistors are, as follows:

Q1 = BC 109

E = 0.00
B = 0.54
C = 1.30

or

E = 7.56
B = 6.86
C = 7.42

Q2 = BC 108

E = 0.61
B = 1.30
C = 0.61

or

E = 6.80
B = 6.20
C = 7.44

Again, sorry I'm not sure which of these reading are right.  As before, the first group of readings (the .0's) were with the black wand on the ground and the read on the transistor leads.

The other, seemingly more hearty readings are with the red wand on the 9V positive coupler and the black on the transistor leads.

Which of these numbers seem right to you? 

[petemoore]

Here's the link to the One Knob Tonebender tutorial.

http://aronnelson.com/gallery/album21
  This is a Neg Gnd FF, Fixed Gain and Bias, and uses NPN transistors

The transistors are, as follows:

Q1 = BC 109

E = 0.00  This ones connected to ground, ok.
B = 0.54  .. .. should be .6v above the emitter
C = 1.30   ...is connected to Q2 Base, and shows same V...good.
  The Black DMM lead Goes to Ground to do these tests, I assume ^ is a measurement taken W black to ground.
or

E = 7.56 and this measures between the pins and V+ supply, IWCase they're moot
B = 6.86   for debugging because we're using ground as the reference voltage...0v.
C = 7.42 

Q2 = BC 108

E = 0.61
B = 1.30  Not too sure about these but lets look at:
C = 0.61 the collector should be @ 1/2v or so, with a battery measureing 9v that'd be reading 4.5v, also it is lower than the base...not biased,
  Try other stuff...suggestions welcome.
  Disconnect the battery, and measure resistance:
  Between Q2 collector and V+ [note and post]
  Between Q2 emitter and ground [rotate gain pot and see whatappens]
  Between Q2 emitter and Q1 Base
  While you're at it[and you are there.. I'm not] check the schematic values and compare to the measurements.
  Something is pulling Q2 collector to a low voltage..misbias.

or

E = 6.80
B = 6.20
C = 7.44

Again, sorry I'm not sure which of these reading are right.  As before, the first group of readings (the .0's) were with the black wand on the ground and the read on the transistor leads.

The other, seemingly more hearty readings are with the red wand on the 9V positive coupler and the black on the transistor leads.

Which of these numbers seem right to you? 

[somasix]

All right,  I took those measurements again to double check, and they seem to have changed slightly.  The current measurements are as follows:

Q 1 (BC 109)
E = .oo
B = .59
C = .68

Q 2 (BC 108)
E =.59
B = 1.28
C = .60

I'm not sure how to measure resistance.  When I tried the measurements you requested with the battery removed the ensuing readings were a continually  descending scale of numbers that ended at 0.  These measurements were attempted with the knob of my DMM set to 20 DVC.  Is that correct?  I felt like there were specific numbers you were looking for beyond 0 that I was not getting on these tests.

My own concerns were that my 10u Elec. Cap. and 820K Resistor were reading 0 also (these were not along the ground signal path).  Could that be a problem also?

Thanks for your patience.

[petemoore]

The current measurements are as follows:
  ...you mean the most recent voltage measurements I surmize.
  Your voltmeter should have a number of settings related to resistance, or...'R', set the dial to an R range on the DMM, it probly starts with '200', that'd measure 200ohms and less, set it to 200k if it has that, or something above 100k ...[since that's the largest resistor on the board], grab a resistor, read and decode the color coding stripes on it, measure it to verify you are indeed measureing resistances and getting 'reasonable, readable, measurements, your readings should fall 'close' to the resistors marked value.

[somasix]

So, I disconnnected the battery, which is getting  8.9 Volts, by the way, and used the 200K setting on my DMM under the Ohm symbol heading.  The readings I got are as follows:

1. From the Q2 Collector to the V+, there was no reaction whatsoever from the DMM.

2. From the Q2  Emitter to the ground is 0.09 when potted up to 0.00 when potted down.

3. From Q2 Emitter to Q1 Base the reading was 146.2.

As far as comparing the schematic values against the DMM measurements, I'm not sure how to do that, as there was no schematic with the tutorial (just the layout) and I've never seen a schematic for this circuit, or actually come across any other mention of it then this thread.

Also, something else I discovered, when the guitar is plugged in, and the effect is switched on, the pot seems to run as an overall volume knob.  As it is potted down, the signal seems to drop out completely. 

[petemoore]

So, I disconnnected the battery, which is getting  8.9 Volts, by the way, and used the 200K setting on my DMM under the Ohm symbol heading.  The readings I got are as follows:

1. From the Q2 Collector to the V+, there was no reaction whatsoever from the
DMM. 
>>The schematic shows a 10k resistance between these two points, and I see no other way for current to flow between them than through a 10k, perhaps there is an open connection there?
2. From the Q2  Emitter to the ground is 0.09 when potted up to 0.00 when potted down.
>>Perhaps turn the DMM to a smaller R range [like 2k?], then take the reading...I suspect that decimal point might mover over one space and make this look more like the 1k pot your adjusting/measuring AShown OT schem. I forgot there is preset gain, no gain pot...the 1 knob TB...
  Carefully read the color code of Your gain resistor, shown on schematic as 1k [brown black RED]. It is easy to mistake red for brown, the reading here, @ 10x to small resistance draws suspicion to the gain resistors value.
3. From Q2 Emitter to Q1 Base the reading was 146.2.
>>should be 100k [brown Black Yellow], this looks like a reading from a 150k [Brown Green yellow].
  As far as comparing the schematic values against the DMM measurements, I'm not sure how to do that, as there was no schematic with the tutorial (just the layout) and I've never seen a schematic for this circuit, or actually come across any other mention of it then this thread.
  You've pretty much done it, just read a *resistor off the schem, find that on the board, measure the *resistor on the board, compare the two numbers. Note what I said about 'alternate current path through the circuit', when measuring resistors in circuit, there is sometimes an alternate path, which will lower resistance, hence you can't trust every measurement...you have to figure 'can it go this way through another path'...measured resistances higher than the schematic resistances Do Show a misvalued board resistor.
>>This is a way to just apply the DMM and look at board components from a R point of view, I've often fairly quickly found misvalues and also 'open connections' [misnomer, alluding to "Looks Connected/Is Not actually Connected].


Also, something else I discovered, when the guitar is plugged in, and the effect is switched on, the pot seems to run as an overall volume knob.  As it is potted down, the signal seems to drop out completely. 
  It is a volume knob. The gain of the 2 transistor feedback loop amp is preset by the 1k resistor.
  I find it's much more linear and...easier to type about when looking at the schematic...the vero board is 'color by number' and because the circuit is twisted, mental confusion abounds when I view one for reference, it is extremely easy for me to view a schematic of a FF, and use that for referring to, like a map it is alot quicker and less confusing to type about.
  http://www.generalguitargadgets.com/diagrams/fuzzface_sc_nn.gif
  Notice the small differences, gain knob...whatever, it's real close and same topology.
  Input goes through DC blocking cap [which Blocks input DC and rolls off lows Depending on size]
  ->Q1B amplifies, needs the bias resistor on the C to work 33k-100k'll ;work'...
  Q1C's amped signal Feeds input to Q2.
  Output cap from Q2's C resistor blocks output DC and rolls off % if valued to
  The 100k takes some of Q2's 'wiggle' and feeds it back to Q1 base, minus what the ~1k shunts to ground.
  Another trick is set the DMM to beep mode for checking continuity and check continuity points chosen from/while looking at the schematic, this and the resistor testings...
  Anyway, some of the resistances notes looked off, could be a misnomer reading or something, try looking there for the color codes, triple check anything you don't think needs double checked, apply the meter using V, R, and beep settings...you're looking for something that isn't shown on the schematic...but...DOHH...I always build on perf and follow the schematic is real easy/straightforeward...from now on and when I typed 'schematic', substitute 'layout'....
  BTW you did drill out the red squares to break the necessary traces where shown?

[somasix]

I do appreciate you teaching me how to use my DMM.  It has helped.

Please find below, my most up to date reading of the resistors against their identities on the schematic and the setting I was using on my DMM.  Starting from the input end of the circuit:

1M = 984 @ 2000K Ohms setting on DMM
150K = 146.4 @ 200K Ohms setting on DMM
1K = .97 @ 20K...
10K = 9.93 @ 20K...
820K = 814 @ 2000K...
2K2 @ 2.17 @ 20K

This time when I took the measurement from Q2 Collector to V+ I got:  817 on the 2000K setting of my DMM.

When I redid my measurement from Q2 Emitter to the ground I got 983@ 2K when the pot was positioned hard right and hard left. 

I still got the same value from Q2 emitter to Q1 base: 146.2.  Why should it be 100K?  The only reason I ask is because there's a 150K along that same strip of copper.  The only thing that's between it is the 220p.

I did resolder a joint on the 10K as during one of my first debugging attempts.  Do you think I should do it again?

Unfortunately, my DMM doesn't have beep sound.  How do I check for continuity in this circumstances?

Thanks again.

[somasix]

Oh yeah, and I did drill out the traces, dutifully making sure there were no shreds of copper that might mess up the circuit.

[somasix]

So, I resoldered that 10K and the farty, crackle noise seemed to come through a bit more.  I resoldered the potentiometer, and now any effected signal is GONE!   I do not understand why every attempt I make to debug any of these projects pulls me further and further away from my goal of successfully completing more than one project in four months.  Now the only time when I get any hint of guitar signal through the effect is when I hold the input and the output.  In that case I feel like I'm completing the circuit and it's bypassing the pedal altogether.

Here are some new questions that have arose as the result of my highly successful attempts to fix this very simple circuit:

Could I have burned out the pot?  What about wires?  Could this be the product of a burned out wire?  I replaces the wire from the circuit output to the pot, now I'm wondering if I fried my board (which hasn't really happened since I got my new iron) or maybe the .22u capacitor.

Before I wanted the effect to work.  Now I miss the moments of expectant enthusiasm provided by that long lost crackling noise.  For all I know the crackling noise was a well placed mistake anyway that my resoldering just pulled out of the way, but it's so hard to feel like I'm getting anywhere. 

[petemoore]

Could I have burned out the pot?  What about wires?
  Doubtful, but the pot can be tested by measureing it while turning it, you may need to disconnect it to do so, but I don't think so in this case, measure from wiper to each side, turn it and look for dead spots.
  Could this be the product of a burned out wire?
  can be measured, I doutbt it
   I replaces the wire from the circuit output to the pot, now I'm wondering if I fried my board (which hasn't really happened since I got my new iron) or maybe the .22u capacitor.

[somasix]

Thanks for the advice.  I checked the pot and it doesn't seem to have any dead spots. 

I've learned an enormous amount about my digital multimeter as a result of this circuit.  Firstly, I should probably get a better one, huh? 

I would like to get this circuit going.  While the tutorials have been nothing if not helpful when it comes to the builds, and my style has gotten much better, it's the debugging process that seems the hardest for me to wrap my head around, especially when I look down at my circuit and all the pads of sodder are neat and shiny, I heat sinked every component before soldering, followed the directions to a T.  Please, where do I go from here?

[petemoore]

Thanks for the advice.  I checked the pot and it doesn't seem to have any dead spots. 

I've learned an enormous amount about my digital multimeter as a result of this circuit.  Firstly, I should probably get a better one, huh? 
  Yes, you've learned more than you realize already, debugging a circuit is easy or hard, beyond 'classic debugging techniques' it's luck of the draw type affairs. Between the audio probe and the bias checks, the stage with the problem can generally be located quickly.
  Thing about the FF being an amp stage, and having 2 transistors is it's bias is a little more complex than a 1 transistor stage, Q2 mostly sets the bias for the circuit.
  I would like to get this circuit going.  While the tutorials have been nothing if not helpful when it comes to the builds, and my style has gotten much better, it's the debugging process that seems the hardest for me to wrap my head around, especially when I look down at my circuit and all the pads of sodder are neat and shiny, I heat sinked every component before soldering, followed the directions to a T.  Please, where do I go from here?

Tuff nuts break easier after a 'while'...
  Hopes high and expectations...low...I sezz, you can count on certain things, as you may well have noted, debuggingagainagain and again are more than a few of them, I'm workin' an Opamp circuit that is...plain wrong...it's refusal to follow logic astounds me...it's ability to sit on the bench and illicit no fondness in me is nearly infinite. It most likely will recall bad memories, and will become a scavv item.
  Let it sit.
  Did you try coppin' a reading with DMM on R range[s for every resistor on the board?  I used to get the decimal point off on the 470ohm ... off by a factor of only 1000x, I'd grab 470k's...did it on a few FF's for a short period....finally figured that one out...
  I use a testjig, and no switches and jacks to test and debug my boards, it has it's advantages.
  I like perf opinion, I find just following the dern schematic makes on the board topology [placement of parts and connections for the most part] makes following the schematic and comparing it to what the board has on it is alot easier, debugging a Vero, IMO, especially when you don't have a FF schematic burned into your brain [schematic of FF to perfboard builds did that to me], following the connections...well not too bad...just use the Ver0 Layout...
  Look at each node, start with node '1'...the input cap, 100k and Q1 base all connect....that's 3 connections which can be verified with DMM...I leave probe room atop the board [a little 'extra resistor lead there] so that I can check things.
  Anyway count the connections at each node.
  We didn't talk about capacitor orientation...important...
  Transistor pinout, we did talk about, but that's a long story best re-verified...how many times...a real gotcha again when you were Sure thing/
  Q1E, the 1k's outer lug, the 22uf, the Black Battery lead, and the volume control should all 'beep' the DMM...these ground points all connect.
  Battery + goes between 33k and 470ohm.
 

 

[petemoore]

  Any Luck?
  Perhaps a suggestion...
  Do one up on a chunk'o perfboard, leaving leads atop board of resistor legs for probe access, or even mods...that way they're 'right there' and easily identifyable...also if you pretty much follow the schematic...you have a much more 'linear' build, making it much easier to follow the lineage of it.
  Socket Input Cap, Output cap, both transistors, replace Q2Collector resistor with a 10k-20k trimpot, be extra careful and measure every resistor just prior to installing it, count every node before soldering...
  It might sound like the long way around, but could also be the shortest route to a 1KTB.

[somasix]

So far no luck.  I'm going to have to order new transistors if I'm going to build this thing again.  I fear the most frustrating thing about this is someone local with the a bit more experience could probably look at my work and show me whats wrong.  It's not that I want someone to do my work for me, it's just not necessarily intuitive though.  Although I learn something new every time I fail at another project, I would like the growing pile of dead circuits on my workbench to actually work.

Interpreting the One Knob TB for perf would probably help my understanding of laying out a project.  Give me a day or two to look over the layout and I'll scan a potential hand drawn schematic for your perusal, how about that?  It would definitely help me to have someone to verify, for me, what would otherwise seem to be a wild stab in the dark.

Do you recommend me buying a breadboard?  There's a few spare dollars at the end of the week and I think it might be cheaper to figure out how things work without spending tons of dough on parts that will be stuck to a non-working board.  Although I gather from the forum that just because it works on breadboard doesn't mean it's going to work on perf.

Having never worked with trimpots, I would be interested in finding out which trimpot I should purchase.  Any recommendations?

What's a node?

Which resistor is the Q2 collector resistor? 

As nice as it was to have an introductory tutorial to stripboard, without the schematic I definitely feel like I was just painting by numbers without a big picture perspective on what the various components on stripboard do.

I will definitely measure every resistor on my multimeter prior to installing it.  What setting should I use to measure capacitors and transistors on a DMM?

I'll work on my layout for the perf and submit it as an image to this thread for you take a look at by Thursday.  Chances are the build won't actually start till next week though, cause I have to get the parts from Small Bear.  Thanks for your help.