Tone Burner: First Build Report

[ke4unr]

Tone Burner designed by Tobias Karlsson.

http://www.generalguitargadgets.com/diagrams/tb3tb_lo.gif

Except for a few minor issues listed below it works very well. I've got plenty of headroom and it sounds great!

I used JD's PCB and followed the layout pretty close.

I eliminated the Tightness switch (SW2) and instead placed a 10uf electrolytic cap on the board next to R6 and a jumper across to it.

I swapped the positions of the Volume and Treble pots (R13 & R20) for a more "normal" layout.

The String pot (R19) operated in reverse, so I swapped the wires on the outside lugs.

Instead of an SPDT for SW1, I used a 3PDT for True Bypass, to add a DC jack and LED.

I used sockets for the transistor set which came from Small Bear.
Q1 is a Hitachi 2SB77 with an hFE of 65, Q2 and Q3 are TI 2N404 at 75 and 131.

I couldn't locate the pinouts for these, but believe I have them oriented correctly.

Issues: The Mud pot (R7) goes from all the way off (no signal full anti-clockwise) to louder. But, otherwise I don't hear any tonal difference. Is this the normal function?

Also, I hear no difference when turning the Treble pot (R20) from one end to the other. The Bass pot (R11) seems to work fine. I have the dark blue wire from the Output at C9 going to the first lug of the Treble pot. Nothing is connected to the third lug. The center lug is wired to the center lug of the Volume pot, with the first lug wired to ground and the third lug wired to the center lug of the Bass pot (R11).

Using a battery measured at 8.68 VDC I get the following readings:

Q1
C = -3.02
B = -1.53
E = -1.45

Q2
C = -3.01
B = -1.45
E = -1.32

Q3
C = -3.38
B = -0.10
E = -0.00

D1
A = -0.10
K = -0.00

C3
+ = -0.00
- = -8.54

C5 (10uf mounted on PCB next to R6)
+ = -0.00
- = -1.32

This is my second build out of three recently. The others being the BSIAB II and a DOD 250 with "Gray" specs. This is my first post. I hope I gave enough information, but not too much. Please let me know.

Any help would be appreciated.

Thanks,
Ray K.

p.s. I'm attempting to post photos below.

[QSQCaito]

I don't know much, but i do know that in electrolytic caps the (+)pin voltage should be always higher than the (-)pin voltage. If im not wrong, you measured all your voltages with the DMM(+) lead connected to ground, thats why all your voltages read negative. If we change the sign too all of them, you are having higher voltages in the negative leads of the electrolytics than in the positive. Are they oriented correctly??


Bye bye

Hope it helps

DAC

PS photos still opening, i might guess they're pretty for the little i have seen.

[ke4unr]

I don't know much, but i do know that in electrolytic caps the (+)pin voltage should be always higher than the (-)pin voltage. If im not wrong, you measured all your voltages with the DMM(+) lead connected to ground, thats why all your voltages read negative. If we change the sign too all of them, you are having higher voltages in the negative leads of the electrolytics than in the positive. Are they oriented correctly??


Bye bye

Hope it helps

DAC

PS photos still opening, i might guess they're pretty for the little i have seen.

Hi DAC, this is a positive ground circuit. I measured with my meter's ground probe clipped to ground and poked around with the positive probe for the readings. This is the first positive ground circuit I've worked on, so I had to be extra careful not to get confused. The electrolytic caps are oriented properly according to the layout I linked to above.

Thanks,
Ray K.

[ke4unr]

Issues: The Mud pot (R7) goes from all the way off (no signal full anti-clockwise) to louder. But, otherwise I don't hear any tonal difference. Is this the normal function?

CORRECTION: Sorry, but it is the String pot (R19) that seems to do nothing much. The Mud pot seems to be functioning fine and adjusts the gain of the pedal very nicely!

Ray K.

[tungngruv]

Nice looking build Ray! I love the clip on GGG that Tobias played for this pedal!

[ke4unr]

Nice looking build Ray! I love the clip on GGG that Tobias played for this pedal!

Thanks for the kind remark! Yes, that clip hooked me the first time. I'm pleased that the pedal does the tones heard on it. I just need the killer chops that Tobias has, hehe!

Ray K.

[QSQCaito]

I would suggest you to recheck everything solder blobs etc... if it's all correct it should work.. there's little probably a cap or a resistance coming broken from fab

bye bye

hope it help

[ke4unr]

I would suggest you to recheck everything solder blobs etc... if it's all correct it should work.. there's little probably a cap or a resistance coming broken from fab

Yes, I retouched ever solder joint on the PCB and took a close look at the ones offboard several days before posting this report. Today, I changed the wiring of the Volume and Treble pot to how it is shown on the layout. It made no difference, the Treble pot still seems to do nothing.

Thanks,
Ray K.

[ke4unr]

A few things that I just tried:

Continuity check between Treble pot and C9 is good. I feel confident that my solder joints are fine.

DC measurements before and after C9 shows 0.0 Volts. Any clues?

I reversed the orientation of Q2 and Q3 (CBE to EBC) which seemed to have no effect on the way the pedal operated. Does anyone have the pinouts for these transistors, or can you point me to a source?

Thanks,
Ray K.

[tungngruv]

Hey Ray, I noticed on the schematic that c9 is a 2.2uf. I know you probably already checked but are you sure on your build that c9 is truly 2.2uf? I can't see from your picture and the reason I ask is 2.2uf caps around my area are all polarized electrolytic. Also, the wiring diagram shows two wires on lug 2 of the treble pot, one going to output and the other going to lug 2 of volume. Yours build has the two wires on lug 2 of the volume. It probably will not make any difference but you never know? I remember some of my builds had to be wired exactly like the diagram in order to work right. I think it was my Tube Reamer or AMZ OD pro. Sorry if this seems stupid but I'm just trying to help out.

[tungngruv]

I reversed the orientation of Q2 and Q3 (CBE to EBC) which seemed to have no effect on the way the pedal operated. Does anyone have the pinouts for these transistors, or can you point me to a source?

Aron's FAQ has a diagram and Jack Ormans got a great page:

http://www.muzique.com/schem/pinout.gif

[ke4unr]

Aron's FAQ has a diagram and Jack Ormans got a great page:

http://www.muzique.com/schem/pinout.gif

Many thanks for the link! The two TO-5 transistors I have are socketed correctly.

Thanks,
Ray K.

[ke4unr]

Hey Ray, I noticed on the schematic that c9 is a 2.2uf. I know you probably already checked but are you sure on your build that c9 is truly 2.2uf? I can't see from your picture and the reason I ask is 2.2uf caps around my area are all polarized electrolytic. Also, the wiring diagram shows two wires on lug 2 of the treble pot, one going to output and the other going to lug 2 of volume. Yours build has the two wires on lug 2 of the volume. It probably will not make any difference but you never know? I remember some of my builds had to be wired exactly like the diagram in order to work right. I think it was my Tube Reamer or AMZ OD pro. Sorry if this seems stupid but I'm just trying to help out.

tungngruv, thanks for trying to help! Don't assume anything! Well, I'm not sure what to think about the value of C9.

The schematic: http://www.generalguitargadgets.com/diagrams/tb3tb_sc.gif
and the parts layout: http://www.generalguitargadgets.com/diagrams/tb3tb_lo.gif
both show a 2.2nf (nano). This would equate to a .0022uf, which is what I used (I'll double check though).

But the materials text: http://www.generalguitargadgets.com/bom/tb3tbbm.txt
lists a 2.2uf.

I guess I need to check with J.D.

As for the wiring, I didn't think it would matter either, but just yesterday I wired it according to the diagram. There was no change. Oh well, it didn't hurt to try.

Thanks again,
Ray K.

[tungngruv]

Please at least keep me updated about how this turns out and what the cap should be.

[8mileshigh]

Your wiring is nice and clean, good job.  My pedals look like a dog's breasfast by comparison.

8

[ke4unr]

Please at least keep me updated about how this turns out and what the cap should be.

Will do! I sent J.D. a message today.

Ray K.

[ke4unr]

Your wiring is nice and clean, good job.  My pedals look like a dog's breasfast by comparison.

8

Hi 8, very nice comments - thanks! But, you'll notice I showed no pics of my desk/workbench...

Ray K.

[ke4unr]

Please at least keep me updated about how this turns out and what the cap should be.

J.D. reports that C9 is correct as shown on the schematic and layout - 2.2nf, or a 0.0022uf which I used.

He will correct the Materials Text to include the proper value.

He is not certain what the function of the String control (R19) is supposed to be. He will check on it.

Meantime, I decide to changed out diode (D1) to the NOS Germanium diode that was include with Q3 from Small Bear. I had initially used a 1N270 which sounded fine to my ears. But, the "matching" diode brought the pedal even more into "fuzz" territory! I have tons more gain, and at first wasn't sure I liked it. But after playing for about an hour through it, I just dialed back the Mud (gain) control more and found it pleasing.

I'll run it some more like this to verify, but I can always change back easily. Or, possibly add a mini SPDT to switch between the two diodes. Hmm, I just thought of that! It might be worth doing...or if the String control proves to be of little value, maybe I could use it as a variable control to blend from one diode to the other (?).

Anyway, if I can just get the Treble control working, I believe I will be very happy with this build. It already sounds really good to my ears.

I'm wondering if I should try swapping out the C9 cap just in case it is bad (?).

I also plan to use my audio probe again. I ran short of time a few nights ago, but I had signal to just before D1, and if I remember correctly, just after. But, I had no signal or at least noise at C9. That's why I'm suspecting it is the problem. I'll verify though and report back.

Ray K.

[ke4unr]

Anyway, if I can just get the Treble control working, I believe I will be very happy with this build. It already sounds really good to my ears.

I'm wondering if I should try swapping out the C9 cap just in case it is bad (?).

I also plan to use my audio probe again. I ran short of time a few nights ago, but I had signal to just before D1, and if I remember correctly, just after. But, I had no signal or at least noise at C9. That's why I'm suspecting it is the problem. I'll verify though and report back.

I ran my audio probe through the circuit last night and am getting signal throughout, including through C9 and to the Treble pot (R20).

I metered the 50k ohm pot and am getting 0 - 48.4k ohms throughout the sweep. I checked both sides, even though the third lug is N.C.

I did continuity checks at various points between the PCB and offboard signal points (pots & jacks).

I closely inspected, yet again, all solder points on board and off. I touched up one "suspect."

I compared the schematic against the parts layout diagram, and the logic seems identical to me.

I did not change out C9. I don't have a cap close to that value on hand. I guess I should try the closest one I have to see what results I get (?).

This has me totally baffled! If anyone has any suggestions or advice, I would greatly appreciate it!

At least the pedal sounds really good, to my ears. So, while I would love to have the Treble control working properly, I've pretty much thrown in the towel. I'll use it as is.

Thanks,
Ray K.