DIYstompboxes.com

I just finished building a ToneBender MKII with parts from SmallBear and a PCB from GGG...


Well...it works...but I don't know if this is how a ToneBender is supposed to sound:

http://www.voxblues.com/guitar/mk2.mp3

As you can hear, the fuzz fades out as the signal gets quieter. It's almost like there's a threshold that activates the fuzz...above that you get distortion, below that you get a clean guitar. I recorded direct, so the ringing guitar sound you hear between fuzz intervals is actually a clean signal passing through unaffected...the fuzz has cut out entirely, but the signal continues to pass.

Any suggestions? I've been mostly plug-n-play up to this point (a couple of paint-by-numbers DIY kits and some True-bypass conversions), so treat me like a newbie. I just got a multimeter, though, so I'm ready to dive in and start learning how to debug...

Thanks in advance...

Definitely read through the FAQs and tutorials on debugging, that sounds very much not right. In particular, take some voltage readings from the legs of the transistors and post them here (if you're doing a PNP circuit clip the black (-) lead of the meter to the leg you want to test and the red (+) lead to ground)

It sounds badly, badly mis-biased. Did Steve send recommended resistor values and did you use them. Also, are you sure you used the transistors in the right sequence, i.e. 1 thru 3 as I know he labels them?

RDV

Yep, it was all from Steve...I put the trannies in as labeled, and when I placed the order, I told him that it was for the MK2, and that I needed the proper resistor values.

He sent the same resistors that were listed on the GGG layout.

What voltage reading are you getting on Q3's collector?  It usually sounds best to me when it's approximately half the supply voltage.  Replacing the Q3 collector resistor with a 25K trimpot is a common mod that allows you to dial in a good sound.

HTH!

Jim

Sorry for the newbie question, but how do I measure the voltages on the transistor?

I know I would put one of the test leads on the part in question (like the Q3 collector)....But where does the other lead go?

The other lead goes to ground. Use the ground pad on your board, or if you're sure your wiring is good, use the ground on your jack. Set your DMM for 0-20v. Turn on the pedal, and plug a patch cable into the input jack.

And post the voltages from all your transistor leads. Also, post the voltage of your battery. List them something like this:

Q1: E
     B
     C
Do that for all three transistors. Also, double check your tranny pinout orientation.

My battery reads 7.48V

Q1
C: .25
B: 7.07
E: 7.15

Q2
C: 5.8
B: 7.01
E: 7.15

Q3
C: 5.99
B: 5.81
E: 6.00

Try a fresh battery!

It does it even with the 9V power supply plugged in.

Ditto, the battery is too low to gauge your voltages.

Quote from: mrsageIt does it even with the 9V power supply plugged in.

Does what? You get the exact same voltages with a power supply? Using a fresh battery helps alot since we don't know how much your power supply is putting out.

How is this wired? pos ground or neg ground? What are the trannys, PNP or NPN?

Did you double check your tranny pinout's?

It's a PNP, negative ground wiring, per the GGG layout. I triple-checked the pinouts on the trannies.

The effect (or lack thereof) is the same using the power supply. Here are the voltages with it plugged into a wallwart (I can't find my fresh batteries):

Q1
C: 0.30
B: 9.42
E: 9.50

Q2
C: 7.80
B: 9.35
E: 9.50

Q3
C: 7.99
B: 7.80
E: 8.00

Those voltages are way off, more than a misbias problem. Time to check for cold solder joints, bridged (touching) traces, and correct component values. Whip out the magnifying glass and double check the traces on the board to make sure none are touching.

Another problem that may come up when all else is checked, is that sometimes (not all the time), a pnp tranny fuzz will not cooperate when wired neg ground. When this happens, the only fix is to go pos ground. Battery life is very good anyways on these.

Ballpark, once you start getting voltages in the ballpark, use [and post] the supply voltage as a reference to what the other voltages should be %age wise.

Well, I think I'm in over my head.

I re-wired it to positive ground, per the diagram on GGG, and now I'm getting no LED and very low (or no) voltage readings.

Q1
C: 6.96
B: 0.05
E: 0.00

Q2
C: 1.34
B: .014
E: 0.00

Q3
C: 1.16
B: 1.34
E: 1.15


That's with the same 7.4 V battery.  I probably messed up the capacitors or something, but I don't have any spares to swap out, so I can't be sure.

Thanks for the help...looks like this is getting shelved for a while.

:cry:

You're a lot closer now. The emiters of Q1 & Q2 should be at zero. Q1's collector looks much better. Q3's collector is low, it should be half your battery.

Hmm...okay....

I'm a little less depressed about it now.

What else should I look for to help the Q3 collector be all he can be?

And why isn't the LED coming on anymore?

Try dropping R6 (8k2 from Q3's collector) down about 2k, to somewhere between 5-6k.
http://www.generalguitargadgets.com/diagrams/tonebender_m2p_lo_pp.gif

Quote from: mrsage
And why isn't the LED coming on anymore?

When you rewired it for pos ground did you remember to turn the LED around (neg flat side of LED).

Pos-ground: neg (flat) of LED goes toward resistor
http://www.generalguitargadgets.com/diagrams/tonebender_m2p_lo_pp.gif

neg-ground: neg (flat) side of LED goes toward switch
http://www.generalguitargadgets.com/diagrams/tonebender_m2p_lo_pn.gif

No real progress...

The only resistors I had laying around were 4k7, so I tried one of those:

Q1
C: 6.68
B: 0.06
E: 0.00

Q2
C: 1.43
B: 0.13
E: 0.00

Q3
C: 1.29
B: 1.43
E: 1.24


And I double-checked the LED...I definitely flipped it and wired it as shown in the positive ground diagram.

Quote from: Fret WireTime to check for cold solder joints, bridged (touching) traces, and correct component values. Whip out the magnifying glass and double check the traces on the board to make sure none are touching.

You already rewired for pos ground. Did you thoroughly check the above? That also includes polarity of caps too. Assuming the LED is good, there's also a wiring problem. At this point, it's best to remove all off board wiring from the pcb. Just hook up the battery only, and check voltages. Then you can be sure if the problem is on the board, or the off board wiring and components.

Yeah, I checked the traces, and it doesn't look like anything's out of the ordinary. Caps are pointing in the right direction and all component values are correct...

Okay...I unhooked the board and wired a battery with the negative going as shown on the diagram and the positive going to ground (I assume that's the way to do it?)

Q1
C: 6.94
B: 0.05
E: 0.00

Q2
C: 1.75
B: 0.15
E: 0.00

Q3
C: 7.07 (with original 8k2 resistor reinserted)
B: 1.75
E: 1.73

what's your battery voltage?

Same battery... 7.4 V

I'm getting some fresh ones tomorrow...Should I re-test and report then?

Yes, it will be more accurate with a fresh battery. Also, now you need to go higher on the 8k2 (R6). Believe it or not, it is coming together.

Those are some strange readings even with a low battery like that. What value do you have at R5?

RDV

Quote from: RDVThose are some strange readings even with a low battery like that. What value do you have at R5?

RDV

1K

Okay...fresh Battery: 9.39 V

Q1
C: 9.07
B: 0.05
E: 0.00

Q2
C: 2.23
B: 0. 16
E: 0.00

Q3
C: 9.11
B: 2.23
E: 2.19

What value is in R6 right now?

8k2

Q3's collector needs to be at half your supply voltage (about 4.7 with your battery), so try around 10k and check all the voltages again.

I recently bought the mkll transistor set from Small Bear and the board from GGG. I did test the board with my meter and noticed that two of the traces were bridged by the copper around one of the mounting pilot holes. This was no big deal since lightly scraping some of the copper around the mounting hole with a razor blade quickly rectified the problem. The sheet that came with my transistors listed the same (stock) resistor values as well. My transistors have the following gains: 65, 81, 130. What were yours like? I am seriously thinking about following the great advice given on this forum and replacing the 8K2 resistor with a 20K trimpot just to be sure I will be able to bias it correctly when I finish building it. This is a newbie question but I was wondering what type of trimpot should I use for this board and where can I order one? I am about ready to place an order with Digikey and would like to order the correct part from them if possible. All of the trimpots I have found appear to have three legs and will not fit my board in place of the 8K2 resistor. Can anybody give me any suggestions, part numbers, etc? I will keep you posted on my progress. I appreciate all of the good advice.

Thank you,

Todd

You probably won't find a trimmer to fit without drilling the pcb. What you can do, however, is wire up a 25k pot in place of the resistor. In other words, a pot or trimmer with long wires running to the resistor pads. When you are done setting the bias, unsolder the pot/trimmer without disturbing the pot, and then measure it with a DMM. Then put the closest value resistor in, and you're all set. This way you can use any pot or trimmer laying around to set the bias.

Thanks Fret Wire. I too was considering that option but I just thought the trim pot would be more convenient. That fact that the trim will not fit changes my options  :D . I was under the impression that the resistor values supplied with the transistors were tested in an actual circuit. After hearing the trouble that Mr Sage is going through with tuning his, I thought I better bias it myself instead of sticking in the values provided.

Thank you,

Todd

Those values he gave you may just work fine. Probably will. The other ckt isn't done yet. If it doesnt respond to a bias change, then it's a component or solder problem.
Fuzz type ckt's are harder to debug, because in addition to all the normal problems a ckt can have, it can add more problems with gain, matching, and leakage problems. Which can mask other problems, and make it a mess to debug.

Okay...Battery: 9.38 V

R6 = 10k

Q1
C:  9.04
B: 0.05
E: 0.00

Q2
C: 2.19
B: 0.16
E: 0.00

Q3
C: 9.07
B: 2.18
E: 2.16

Something else has to be going on...The voltage barely changed...And it was nearly the same when I still had that 4k7 in there, too.

Should I reconnect the rest of the wires? Would that make a difference? I'm still testing with just the battery hooked up...

Something more than biasing. You did hook up the battery correct for pos ground right? Time to check the traces and components again. Do you have a strong magnifying glass? You need to see if there is the slightest copper or solder bridging any traces. Plus you need to check the traces to make sure none have a small break in them. You need a mag glass for this, you eye alone won't see it.

I can't see anything wrong with it. I checked the traces with a magnifying glass, made sure it was all wired properly, double-checked component values.

It's just not working. Not sure what else to try...

Uh...when you turned this all back to positive ground, did you turn the electros back around?

I know it doesn't seem like it right now, but if the PCB was right, and the layout was right, and the parts were placed correctly, then it would be working right now.

I've certainly been through this sort of thing....to the point where I had to put the circuit in a plastic bag, throw it in a drawer and come back to it again some other fine day.

Those voltages tell a tale of unrestrained DC all through that circuit, which is why I asked about the electrolytics.

Good Hunting

RDV

Time to take a break for a day or two, and come back with a fresh mind. No sense in wiring up any offboard connections till the board is straight. Then you can concentrate on the jacks, pot, and switch.

Sometimes the harder ones go together easy, and you get one like this that mystifies you. Walk away then come back, and it will go together. We'll be here to help.

Those last set of voltages look much better than the first page set does. The voltages are closer, but don't respond to biasing. Sometimes a tranny doesnt respond to biasing when it is leaking heavily.

I still think theres a solder or component problem. The voltages are off, but proportional to each other. And Q1 & Q2's emitters are at zero. Something is staring us right in the face, and we're missing it.

Quote from: RDVUh...when you turned this all back to positive ground, did you turn the electros back around?

Those voltages tell a tale of unrestrained DC all through that circuit, which is why I asked about the electrolytics.

I turned them in the correct directions when I rewired. One needed turning, and I needed to move the jumper from one place to another. The other two caps kept their original orientation (according to the layout on GGG, anyway...let me know if that's wrong...)

I'll take a break for a few days. I need to play more guitar anyway.  :D

On the bright side, I got a vintage Big Muff working again. Found it on eBay for like $35, and it turned out to be a simple fix. That's always nice. I'm going to try a tremulus lune next...maybe I'll order that and get it going while this one is resting.

Thanks for the help thus far. I'll check back in later!

:)

Tremulus Lune? Are you going with Tonepad's layout or Commonsound's?

Commonsound's...are they significantly different?

No differences, really. Commonsounds is where it originated. Their DIY link has a host of mods. Tonepad even links to it. The Tonepad layout is nicely done. You could put it in a 1590b box sideways with 16mm pots.

Okay...I'm ready to try again.

I just desoldered everything and I'm going to start from scratch.

I have an HFE tester on my multimeter...what values should I be looking for on the trannies? Are there any other things I should be testing other than hfe?

I want to make sure they're okay before I put them back in. I'm thinking I might have fried at least one of them and that's why it hasn't been working right.

Measure Q1 thru 3 and post the readings.

RDV

okay, here's the values from the hfe tester.

Q1: 75
Q2: 106
Q3: 168

bump

What are the transistor pins and battery voltages on the rebuilt one?
 I think the gains are in the right order for Q's 1, 2, and 3...

Quote from: mrsageOkay...I'm ready to try again.

I just desoldered everything and I'm going to start from scratch.

I have an HFE tester on my multimeter...what values should I be looking for on the trannies? Are there any other things I should be testing other than hfe?

I want to make sure they're okay before I put them back in. I'm thinking I might have fried at least one of them and that's why it hasn't been working right.

Because of Ge leakage, the readings from your DMM won't be accurate, but they will tell you that you have the pinout right, and that they still work.

If you haven't started rebuilding yet, check the unpopulated board for broken traces with a magnifying glass. Then, check the value of each component before you put them in. When it comes to electro caps, make sure polarity is right before you put them in. As you solder each component in, check the solder joints with the magnifying glass to make sure they aren't bridged before you go on to solder the next joint. When the board is done, hook up the battery and check voltages before you do the off board wiring. You also might want to check your switch with a DMM before you trust it again.

So I reconnected everything and I'm still getting 9 volts on that Q3 collector, regardless of whether it's an 8k2 resistor or a 10k.

What should the voltages be at each end of that Q3 resistor without the resistor in place?

What I mean is, if I remove that resistor I've been changing the value of, what should the voltage be at either of the ends where it was connected?

I'm getting about 2 volts on the transistor end and 9 volts on the other end...does that sound right?

bump
:D

Okay...I'm getting the feeling that people are pretty much done with this topic this time around.

Any last suggestions before I order a whole new set of trannies and parts? Is there any way to test the capacitors other than just replacing them?

:(

I doubt it's the resistors or capacitors. It's probably a wiring mistake I would guess. Either that or some bad solder joints and a combination of wiring and solder.

I assume you went through this page:

http://www.diystompboxes.com/pedals/debug.html

Yeah...I went through the debugging.

I even desoldered everything, checked the board over very carefully, removed all excess solder from the board, examined the traces, then carefully re-wired it all.

I seem to be having the same problem as before, even after all that. I guess it's possible that I wired it incorrectly twice in a row, but it doesn't seem likely...especially since I was doubly careful the second time around.

What layout, what schematic?

It's a PCB purchased from General Guitar Gadgets, and I'm using their layout for the PNP positive ground version.

Reading schematics is probably the next hurdle I need to tackle, but this is only my second full DIY build...

Hello Hello--
   Don't give up!   I still have times when I've gone over everything 3 times and it's PERFECT but still won't work.  Give it some rest and then slowly start again!
Good luck--
Brian.

>It's a PCB purchased from General Guitar Gadgets, and I'm using their layout for the PNP positive ground version.

Oh commercial product. Hmmm, have you contacted JD????

Aron

Yeah. He said that for $20 (plus any parts) I can send it to him and he'll get it working...then send me a summary of what went wrong.

I'd rather fix it myself, but that might be my best option at this point...

It may be something simple you've overlooked both times around. Sometimes when debugging, you can read the layout the same way incorrectly through several re-builds. It can be fustrating like all hell. That's why people get advised to make sure the board is correct before adding the off board components and wiring. It makes later debugging easier. A bad switch, jack, or wiring with an internal break,  can drive you mad as you keep rebuilding over and over again. Then one day, you cannibalize those same parts for another build, that also doesn't work, and it hits you. It can really be dis-heartening.

A fuzz type ckt can add even more problems to the usual list of things that can go wrong with builds. Gain matching, bias, and leakage with Ge trannys can cause their own problems as well as mask other pcb or wiring problems. Add to the fact that a Ge tranny usually won't survive the soldering from several rebuilds (sockets prevent this), which will again lead the person to believe something else was wrong.

We all get that pedal that absolutely defies our best efforts to run. When it's the first or second pedal you've build, it's a pisser. But... it will come together, no doubt.

I'm sure it will come together.

It's just frustrating because I've put quite a chunk of money into this project (parts, enclosure, etc). And I'm not in it for the money or anything, but it's frustrating to know that I could have spent just a bit more for a pedal that works!

Any other suggestions? Or tips on things I could try testing to figure out where my problem lies? I could take a picture of the PCB if that would help. It's kind of messy at this point (lots of scratches where I was making sure there were no traces jumped and whatnot), but if that would help doublecheck that my wiring isn't messed up...

[sigh]

Thanks again for the help, by the way. I'll bet you guys are hoping I get this sussed out as much as I am at this point! :)

Well, I let this sit for a while, then I broke down and bought all new parts for the board. I hadn't used sockets before, so I wanted to make sure I hadn't fried anything. The resistors all tested okay, and the caps were cheap...the only expensive part was the trannies.

They came in from Small Bear today, and I tried socketing them.

Nothing new. The collector on Q3 is still way too high. So I tried putting in a 25k trimpot for R6. When I turned it up to 25k, I noticed that the value on Q3 collector went down...a bit....

It was still at 8+ volts even at 25k.

So I tried a 100k trimmer.

Same deal. I got the value of Q3 all the way down to 7 volts, but that was with 100k on R6!!!

What's going on here? Should I just keep increasing the resistor value until I get around 4.5 volts? Because the voltage is decreasing...just not as fast as you guys make it sound like it should...

And if the value is decreasing, that means there aren't bridged traces, right? Because if there were the value wouldn't change at all, right? Because voltage would be running free?

So the only things "stopping" the full voltage from reaching the Q3 collector are R5 and R6...and I can't change R5 because that connects to C3. So should I just increase R6 indefinitely?

Maybe this is a good time for a quick electronics lesson, too...

I was playing around with just a 9v battery, some resistors/trimpots, and a multimeter.

I connected a 1M resistor to the battery and measured the voltage from one terminal to the end of the resistor, and it didn't go down that much. From 9.3 volts to maybe 8.5 or so.

What am I missing?

Is the elusive "I" in V=IR?

Because I'm wondering what other factors could keep my Q3 voltage from dropping as it's supposed to. Does it matter that I have the battery connected directly to the 9V(-) input and Ground, with no offboard connections?

Argh. This is frustrating.

mrsage - I feel your pain.  I have built a number of effects and gotten them to work after much frustration by stumbling over this and that, replacing this and that.  I am by no means all that savvy when it comes to the theory of electronics, but will offer this.  I just built the 3 knob TB version off GGG and it doesn't work period -  :evil:   but that will be another post...

Before that I built the PNP Neg Grnd MKII and it does work!  Not to insult your intelligence, but the layout your looking at from GGG is the right one, right?  4 different versions - 2xPNP and 2xNPN.

Now for something that might be helpful.  From my tonebender thats working, here are the readings off the trannies:

Battery=9.42

Q1
C=0.61
B=9.13
E=9.25

Q2
C=8.06
B=9.08
E=9.24

Q3
C=1.04
B=8.05
E=8.19

That is with the trim pot in a range that works (a 250K because that's all I had.  How do you have that hooked in there?)- if I adjust it to the point it drops out, voltage on Q3-C jumps to 8+ volts.  So this is how a functioning MKII Q3 behaves.  What it all means?  Well, I'm not  technically savvy enough to explain it intelligently, but I hope this info helps by giving you some comparison - and if anybody with more knowledge is willing to elaborate - fantastic!

Good luck and I'll keep an eye on this thread...

Those voltages seem different from what other people have said...and different from what the Fuzz Central project has listed:

Vin
9.65V

Q1 Vc (hfe=70)
8.11V

Q2 Vc (hfe=70)
1.10V

Q3 Vc (hfe=100)
4.5V


Everyone has been telling me that the voltage on the Q3 collector should be about half of the battery voltage. I just can't get it that low!!!

If someone has already said this to you, then please forgive me, but you've obviously made a wiring or parts placement mistake. There's no other explanation. It's not that hard of a circuit to get going.

RDV

If it were a parts placement error, wouldn't it have to be either the R5 or R6 resistor, though?

Because there's nothing else between the 9v (-) and the Q3 collector!

And I've been over it a thousand times to make sure the values and placement are correct...Is the layout for the PNP positive ground MK-II on GGG correct?

Because I followed that to a T.

:(

Hello Hello-
     I don't know if anybody else made this suggestion, but I've had similar problems and went through the circuit and re-soldered all my connections.  This solved the problem for me.
Just a quick thought..
Brian.

d;lkj

if you could post some decent pics of the board~
i think it might help.
just a suggestioin..

I have been where you're at. It was the transistor Obsidian. I wired it up on perf during a football(american) game, and had probably not paid complete attention to either. It didn't work, and the problem elluded me for more than a month. I had a cold solder joint.

RDV

:roll:

Somewhere around page 2, someone suggested removing all the offboard wiring and just hooking it up directly to a battery.

So I was testing it without any of the other offboard connections after that point...no pots, switch or jacks.

Well, I just now decided to hook everything back up and give it another whirl.

I got about 6 volts on Q3. That was my closest yet, so I tweaked the trimpot, and sure enough: I got it to 4.5 volts pretty easily.

The LED still didn't work, but upon closer inspection, the General Guitar Gadgets layout has both ends of it going to ground (through the switch, of course). I wired up one end to the 9V connection and it worked.

Then I hooked it up to my amp and everything was all good.




So....

Can someone explain why attaching the offboard connections made such a difference? Is it because there is significant current flow through the circuit, and I was getting too much current flowing directly to the Q3 collector? So that wiring everything else up lowered the current, which lowered the voltage?

If so, why would you want to test without the offboard connections?!

By the way, thanks for everyone's help.

I appreciate your hanging with me through this.

Hello Hello--
     More connections  =   more chance for mistakes  [cold solder joint????]
Brian.

Quote from: mrsage:roll:

Somewhere around page 2, someone suggested removing all the offboard wiring and just hooking it up directly to a battery.
 >>>I always use the test jig, [a stack of two boxes, one with 2 mono 1/4'' jacks, the othr just forms an insulated tray for the circuit to sit on. 3 wires with alligator clips are also part of it, they connect to:
 RED: input jack tip
 BLUE: output jack tip
 BLACK: ground on both jacks [sleeves]
 Not much more to it than that, I flop the circuit to the top box 'tray' clip to it red blue and black...plug the guitar in the input jack and amp to the output jack...Im ready to test the board, battery clip, pots, basically everything that's on the 'bare bones' schematic is on my boards, nothing else until the second testing stage which doesn't begin until the circuit passes the first testing stage..which includes
 "decent Voltages at certain points like OA and  Q  pins from ground, and V supply points from ground.
 'normal' Sound comes from output when input signal is present
 The knobs work 1/2 right...seem to do some of what the function of their label specifies or illudes to.
 So I was testing it without any of the other offboard connections after that point...no pots, switch or jacks.
 >>>Most of these circuits need their pots or something where the pots go 'hooked up'' to operate, it's easier to use pots than to figure out how not to.
 Well, I just now decided to hook everything back up and give it another whirl.
 I got about 6 volts on Q3. That was my closest yet, so I tweaked the trimpot, and sure enough: I got it to 4.5 volts pretty easily.

The LED still didn't work, but upon closer inspection, the General Guitar Gadgets layout has both ends of it going to ground (through the switch, of course). I wired up one end to the 9V connection and it worked.

Then I hooked it up to my amp and everything was all good.




So....

Can someone explain why attaching the offboard connections made such a difference? Is it because there is significant current flow through the circuit, and I was getting too much current flowing directly to the Q3 collector? So that wiring everything else up lowered the current, which lowered the voltage?
 First of all I can't picture the circumstance well enough, second...no make this first...you've got the signal path part of the circuit working?
If so, why would you want to test without the offboard connections?!

I find it's just easier to eliminate 'all that garbage' till you need it. By veryifying that the actual 'circuit' [ I wish there were a name for a bare' bones' circuit other than 'bare bones' circuit...the effect part is always different] the offboard wiring is nearly always following a similar pattern...depending on the options"
 battery switched off at I jack
 Jacks [instead of wires coming out saw an old 'old in this case actually means 'old' factory unit with wire/plug that comes out and wrapped around it]
 LED indicator
 LED indicators
 All this stuff adds more to figure out. having a circuit that works makes it easier to figure out what else isn't working. Remember it only takes 1 thing...having a buncha unverified garbage adds confusion.
 Debugging a circuit that has all of the above, or is even already in the box is just plain silly, and the liklihood that ANother problem breaks out as a cold solder that got pulled on, a wire coming loose from being pulled on, wires touching and burning stuff up because it has turned into a gangly mess...
 Unelss I'm missing something here, testing circuits, plugs, jacks, switches, switching arrangements, LED indicator, etc etc etc. is easier when each section hopefully already works. Without initial testing of sections, it is impossible to know this, not that I ever made a mistake.
 Mistakes seem much easier to find and adress one at a time.
 If I have two sections of a circuit, neither pass signal, I also have a combination lock...I may then spend days finding the combination.
 The Tonebender alone being a combination lock. All three transistors must be biased and everything must be right for it to work.
 Testing your box's bypass and on mode should be easy enough. N/P to do with a wire that has an alligator clip at either end and a DMM. I can type more about this if you like.
 Testing the LED should be N/P with a battery and a resistor. The switching can be debugged for this, the Tonebender doesn't need it to function. I can Type about it later too.
 If You're planning on doing some circuits, the 5$ test jig, and the 20 minutes to set it up is worth the effort in time saved. I used a RACO large for the bottom box cause it's heavy, and any cardboard to make the top tray. Test it by plugging a cable to input and test for continuity from other end cable tip to input alligator clip, repeat for output jack, then test that both jacks are grounded to the ground wire clip. mark them at jacks and where wire comes through cardboard or...