My journey to the Tone Bender Mk II (so far)

[newjackruby]

Hey guys,

Noob here. Been at this for a few months now. I was familiar with how to solder and do wiring stuff before I started, but building things is new.

I decided to start with a Tone Bender. Maybe too advanced for a beginner, but what the hell.

I ended up starting with a Mk III PCB from General Guitar Gadgets. I went through a month or so and two boards (due to being too rough while desoldering mistakes on the first one and just charing it) and finally gave up after a ridiculous amount of time troubleshooting. I finished the second one, but could never get it to work. After some further reading, I think I probably had  some issues with the transistors. I didn't know anything about matching or biasing, and was just using three random transistors. Didn't realize there was more to it. Both of those fully populated PCB's are living out the rest of their days at the local landfill. 

I then decided to try something easy to see if I had any skill for this at all, and I am happy to report that I successfully completed a Screaming Bird using a PCB from Tayda, and  it worked on the first try. 

Now, I have returned to my original dream of building a Tone Bender. Decided to go with a MKII this time, because Jimmy Page. So, I got myself a nice set of Flying Dutchman transistors from Small Bear, a PCB from Aion (the Deimos) and forged ahead.

I started working on it yesterday, but I think I've made a wrong turn again. I must have made a mistake ordering parts, because look at how those caps (don't really at all) fit on the board. A bit crowded in the club. Also, I (of course) didn't notice until AFTER soldering them on that these transistor sockets do not match up with the configuration on this board. That ain't gonna work! 

So mainly, just wanted to share my adventures and ask what I did wrong with the parts. Clearly the 10n and the 10uf Electros were not made to be used with this board. I assume there are different sizes?

Anyway, thanks for reading. I'm not sure what I'm going to do now. Probably get the same PCB and try again, although this one seems rather involved and over-complicated for a Tone Bender. Any suggestions? What's the best TBMKII PCB out there?

Thanks!

[Rob Strand]

I decided to start with a Tone Bender. Maybe too advanced for a beginner, but what the hell.

You have done well to stick at it.

Both of those fully populated PCB's are living out the rest of their days at the local landfill.

You can pull the parts off.   Really though you could re-use the parts and the PCB and turn it into another pedal.  Use them to try alternate circuits.   You have nothing to lose.

So mainly, just wanted to share my adventures and ask what I did wrong with the parts. Clearly the 10n and the 10uf Electros were not made to be used with this board. I assume there are different sizes?

Caps have a number of parameters; type, capacitance, voltage and package.   Your problem is you have bought 400V electrolytic caps and the film caps are 300V.   When you go up in voltage the size of the package has a general trend to get larger.   Larger cap values also have a tendency to get larger.  While you can get different sizes even for a given capacitance and voltage the choice isn't infinite.  Each combination of type, capacitance and voltage tends to have a common size with some choice around that size.  As you stray from that size things get harder to find and more expensive.  Another quirk is you might find 10uF readily offered as 16V, 25V and 35V whereas some places might only sell 1uF at 50V.  The reason is 1uF at 16V or 25V is often the same size so they just don't bother stocking them.

[newjackruby]

You can pull the parts off.   Really though you could re-use the parts and the PCB and turn it into another pedal.  Use them to try alternate circuits.   You have nothing to lose.

Yeah, I should have kept them, but throwing them in the trash just felt so good after so much failure! 

Caps have a number of parameters; type, capacitance, voltage and package....

Ah, thanks! I knew there had to be a reason. Thanks for the reply!

[duck_arse]

we sometimes like to point out that newcomer builds fail because the caps aren't big enough.

you have to stick with this board, as I think it's about 95% there. first point - one of those 400V electros is backwards. doesn't matter now, cause you are going to cut those leads up under the caps, and then heat the solder one leg at a time as you pull the leg out of the board. this should prevent massive damage to the board, but I can't gaurantee, much like my spellink.

then get some 10uF 16V caps, or some 10uF 25V, or 35V, and solder them in, taking careful note of those polarity markings on the board. as for your funny transistor sockets, it looks as tho you only need to link across [you could use an old capacitor leg, maybe] the empty middle pad to the soldered peak of the triangle pad.

actually, maybe if you just use your meter to measure the continuity between those pads, there may be traces on all three transistors. I can't see anything in the docs about it, and can only see one linked on the pcb picture.

basically, stay with it, it should be good to go.

[newjackruby]

basically, stay with it, it should be good to go.

thanks

[fuzz guy]

Keep at it, things will eventually start to make sense.

I'm fairly new to this myself and I've had good luck buying full kits with a PCB and all the proper components. I'm sure it's less expensive to source everything individually, but the full kits make it a lot easier when you're just starting out.

Good luck with your MkII, it's my favourite classic fuzz circuit. My next build is going to be a more versatile silicon bender.

[newjackruby]

Update:

Things have really gone south on this project and I'm pretty close to giving up.

I have verified that my transistors, in fact, were fine. (Remember when you were new at this and tested a component using the WRONG SETTING ON THE MULTIMETER?  )

Anyway, everything is in place, and here's something weird: I hook up power and get ready to start biasing and all three pins on all three transistors  all measure FULL POWER! Like -9.43 everywhere! (Yes, I was using the right MM setting this time.) I take the Qs out of the sockets and get the same result.

Again went through the entire circuit and checked every component again and everything is golden.

I have no idea what would cause something like this. 

[Govmnt_Lacky]

Is there any reason you used BI-POLAR caps for C2 and C4?

[PRR]

> Like -9.43 everywhere!

Usually means you failed to connect 0V ground.

[newjackruby]

Is there any reason you used BI-POLAR caps for C2 and C4?

Is that wrong? Seems like that's what the build doc is showing.

[newjackruby]

> Like -9.43 everywhere!

Usually means you failed to connect 0V ground.

I'll check that angle. Thank you!

[Govmnt_Lacky]

Is that wrong? Seems like that's what the build doc is showing.

That is wrong.

Those positions call for a POLARIZED electrolytic capacitor. Notice the (+) on the layout. That is the way they should be oriented when installing them.

[newjackruby]

That is wrong.

Those positions call for a POLARIZED electrolytic capacitor. Notice the (+) on the layout. That is the way they should be oriented when installing them.

Wow. Okay, I think you're teaching me something here.
These are what I have in C2 & C4:
https://www.digikey.com/products/en?keywords=493-15041-nd

They do indeed say Bi-polar. Being a noob, when I ordered these I looked at them and though "They have one lead longer than the other. That's the (+). These are what I want."  Why do these have that longer lead on one side if they're not polarized?

I guess I need to pause for another parts order. Thanks for the heads up!

One of the many things I love about this new hobby is that I learn more and more about electronics with each new bungle. 

[bluebunny]

Why do these have that longer lead on one side if they're not polarized?

Habit. 

Aka, economics.  Why tool-up for three lead sizes when you can tool-up for two?

[duck_arse]

Why do these have that longer lead on one side if they're not polarized?

Habit. 

Aka, economics.  Why tool-up for three lead sizes when you can tool-up for two?

production economics. it's easier and quicker to get one lead [the longer one] in first than it is to try and align both at once.


why would bi-polar caps in polarised positions affect performance? how would it?

[Govmnt_Lacky]

why would bi-polar caps in polarised positions affect performance? how would it?

I cannot answer this question intellectually however, I would assume there is a reason. Otherwise, why would we have polarized capacitors at all? My assumption is that they are used for decoupling and/or to block AC/DC signals.

[PRR]

> why would we have polarized capacitors at all?

They are significantly cheaper.

[newjackruby]

Well, here's one last look at where I ended up:



I replaced those errant bipolar caps and still no go. Still getting full power on all transistor poles, so I'm guessing that my PCB is trashed somehow, which wouldn't surprise me as much bashing and wrangling I've done with it.

I'm gonna try to breadboard this circuit and see if I can make it work like that, and then if I manage to succeed, either buy another PCB or just Perf it.

Over and out. (for now)

Thanks everyone for the replies! I learned some valuable stuff in this thread.

[newjackruby]

Hey guys,

Back again with this project. Almost there! I've shed my previous problems and just have another biasing question.

Using the adjusted resistor values recommended by Small Bear for my transistor set (R3 22k, R4 91k, R6 8.2k) I'm getting close, but my collector on Q1 is reading low at -9.35v (should be -8.5v), which is of course affecting the rest of the Q values down the line. Is this a big enough difference to matter? I haven't done a sound test on this yet, just wanted to get the voltages to the right place.

There is an RX1 spot for an optional transistor to create more leakage. Should I stick something in there? I am no engineer, and have tried researching how much resistance I would need to increase this voltage by 1v, but running into a mountain of data I don't understand.

Any ideas appreciated. Thanks!