Tonebender MKII build not working. Please help!

[Major Sparky]

Hello, last week I started building a Tonebender MKII.  I was following the Tonebender Profesional MKII schematic at http://fuzzcentral.ssguitar.com/mkII.php with a few changes.  I used NPN silicon transistors (2N4401 for Q1 and Q2, 2N5089 for Q3) and changed the schematic so it had negative ground.  The 8k2 resistor was replaced with a 20k trimpot.  The 50uf and two 5 uf caps were replaced with a 47 and two 4.7 uf caps respectively.

I followed this wiring diagram, http://www.diystompboxes.com/smfforum/index.php?topic=970.0 (the one for an LED and DC jack) that's also how I added an LED and DC jack.  The way that I wired ground for the pots and jacks is the same as the diagram found here shows.  http://www.generalguitargadgets.com/pdf/ggg_tb_m2p_lo_ns.pdf

The first time I wired everything up it didn't work at all.  Then I rewired it a bit and resoldered some joints.  The bypass worked and the LED lit up this time.  I went back and redid almost all of the soldering and rewired it a bit and now the bypass works but the LED does not light up and theres still no sound when the pedal is engaged except for some very small kind of hum/buzzing if I turn the pots all the way up and strum hard.

Here are some pictures of the board.  Sorry for the image size.

[texstrat]

Start here, http://www.diystompboxes.com/smfforum/index.php?topic=29816.0

You have some of the information needed, but start checking voltages at your transistors and post those. Check your pots as well. Are you trannies in the right direction?

Post back your results.

[Major Sparky]

I'm getting 0.00 volts for everything.  my meter is working I know for sure.  All my transistors are in the right direction too.

[Major Sparky]

Can anybody help me out?

[jdub]

Well, getting 0 volts for everything would seem to suggest that either you are not checking your voltages correctly or that your circuit is getting no power at all.  Have you double-checked your offboard wiring according to a known good scheme such as those at Tonepad.com or General Guitar Gadgets?  Best bet is to go through the troubleshooting page and follow the steps, as texstrat suggested, then post your results.  Tried and true method.

[Major Sparky]

Well I rewired the power and now I'm getting some voltages readings on the transistors.  The LED is also lighting up now, and now when the effect is engaged I get no sound until I turn both pots all the way up and then I get static and if I strum hard I get some crackling sounds.

voltages:

Q1
E  0.00
B  0.00
C  9.03

Q2
E  0.00
B  .54
C  1.21

Q3
E  .62
B  1.21
C  8.81

Can anybody help?

[juansolo]

I have a feeling, maybe i'm wrong, but the first transistor stage in a tonebender needs to be a germanium transistor to work properly.
The second part of the circuit, the fuzz face part, should work with silicon transistors.

[Major Sparky]

I'm pretty sure they can all be silicon.  There's a silicon version at General Guitar Gadgets, http://www.generalguitargadgets.com/projects/73/84-tone-bender-projects

[juansolo]

It is different around the first transistor.

[Major Sparky]

What do you mean?

[juansolo]

Compare your schematic and the ggg silicon one, you'll see.

[Major Sparky]

I didn't use the schematic from GGG though, I used the one from fuzzcentral.  What am I missing?

[R.G.]

I didn't use the schematic from GGG though, I used the one from fuzzcentral.  What am I missing?

This is the *exact* reason I asked for the help-requester to post a URL to the schematic they actually used.

And js is correct; the schematic you used must have a germanium device as the first transistor.  Yes, it is possible to do one with silicon as at GGG, but you will notice that there is a resistor from collector to base on the GGG. This is to provide some current to the base to turn it on slightly. This bias current is needed for all amplifying transistors. Germanium is different in that as a semiconductor material, it has a leakage current about 1000 times that for silicon. So a germanium device will leak itself a small bias, and that is how it is used in the original germanium version. Silicon leaks so little that you must supply some bias current for it. This is why the GGG version has that resistor.

And at least one version why your circuit, as shown, won't work.

[Major Sparky]

I did post a url to the schematic I used. It's in the first line of my original post.  But thank you for telling me what I was messing up on.  I didn't realize that I had to change things when I went from geranium to silicon.  Thank you.

[R.G.]

Sorry I missed that. It is in fact right there.

[Major Sparky]

That did it!  I added in a 470k resistor between the base and collector of Q1 and now it works.  Thank you guys for the help!