Tonemender problem. Please Help

[compuwade]

Hey there, I just finished my Tonemender using the PCB layout at runoffgroove.com. It functions well and sounds good, but instead of a volume boost, I have a volume drop even at full volume. I used all the stock values and a NE5532 for the opamp. I breadboarded the unit before I decided to build it and I noticed the same thing, but I figured I had something wrong with the breadboard wiring and thought that using a layout would fix the issue. But no luck.

If some one could point me in the right direction, I would very much appreciate it.

Thanks,
Wade

[compuwade]

Still having problems with this one. I really would love some help so I can box it and be done with it. I read somewhere you can get more volume by changing the level pot but there wasn't a value specified. Would 1M be the way to go?

Thanks

Wade

[oldrocker]

I was contemplating building one these.  I wasn't aware there was a volume issue.  This might not matter to me since I was planning on leaving it on all of the time.  R.O.G. does make the best DIY circuits IMHO.  I've loved all the projects I've built from them.

[B Tremblay]

There is no "volume issue" with the pedal.  There is an abundance of volume available.

To the original poster, have you followed the steps outlined in the debugging thread?

[anchovie]

Double-check the resistance across the outer legs of the volume pot and also R12.

[compuwade]

There is no "volume issue" with the pedal.  There is an abundance of volume available.

To the original poster, have you followed the steps outlined in the debugging thread?

Thanks for your reply...Yes I have followed the applicable steps in the debugging thread to no avail. I haven't built an audio probe but I am getting audio and actually it sounds very good. I decided to box it up regardless of the problem, and after playing with it last night, I found that depending on the settings, I get just a hair under unity at full volume. It's really not that bad and is very usable, but if it's not the way it's supposed to work, then I would love to fix it.
I had this problem once before with a RAT that I built, and I found that I had two resistors soldered together at one end. I fixed that problem and looked for the same type of issue with this circuit, but nothing is wrong with the soldering.

BTW, I've built the Condor, Thunderchief, and the Sili Face II, and I must say, all are awesome circuits that forever have a home on my pedel board. Thank you very much for the awesome projects!!

Wade

[B Tremblay]

One thing to keep in mind is that if all three tone controls are at minimum, there will be no output.

I suggest that you re-examine the offboard wiring first.

[compuwade]

One thing to keep in mind is that if all three tone controls are at minimum, there will be no output.

I suggest that you re-examine the offboard wiring first.

Yes, I figured that out shortly after I started testing it. I get just under unity with all controls all the way up. But everything works and sounds as expected. I checked all the offboard wiring and the only question I have is about the switch wiring. First, I didn't have a 200k resistor, so I used a 150k and a 51k in series. I tested the two together and I get 197k..I assumed this should be ok. Also, it wasn't exactly clear to me how to wire the switch. I used a DPDT switch and wired the square pad A&B to the center pole A&B, and wired the round pad A&B to the 1st switch position A&B. The second postion on the switch it not connected. The switch works and sounds as I expect it should.

After looking at the schematic again, I figure the only other things to try would be to replace the 1M resistor, the 47p cap, and the 4.7k resistor on the second stage to see if there is a problem there.

Oh, and one other thing...When I first wired the pots I assumed that the square tabs on the PCB were lug 1 on the pots. But when I wired them up that way, they worked in reverse. So I swapped the lugs 1&3...That worked.


Let me know if there is anything else you can think of.

Wade

[B Tremblay]

Do the IC pin voltages appear normal?

Also, here's a diagram for the Mid Shift switch wiring.  The switch is shown from the bottom.

[compuwade]

Do the IC pin voltages appear normal?

Also, here's a diagram for the Mid Shift switch wiring.  The switch is shown from the bottom.

Thats how I have the switch wired except I have the two green wires swapped. That shouldn't be an issue. I'll check the votages later tonight and get back to you.

Thanks again for all your help!

Wade

[B Tremblay]

The orientation of the wires does not matter, just that each half is separate.

[compuwade]

The orientation of the wires does not matter, just that each half is separate.

ok, I checked the voltages to the IC and here's what I got:

Vin = 9.11
Pin 1&2 = 4.57
Pin 3 = 2.26
Pin 4 = 0
Pin 5 = 3.14
Pin 6 = 4.47
Pin 7 = 4.37
Pin 8 = 8.77

Vin and Vref seems normal to me...I'm not sure about the votages to the other pins.

Thanks,
Wade

[compuwade]

OK, well...I'm not sure how this happened, but the 4.7k resistor mysteriously turned into a 270k without my permission!! 
I guess I was dyslexic the 20 times I looked at the circuit I thought I had the right one in there. I replaced the 270k with the right one and of course all is good now!!. And you are right...it has plenty of extra volume. What a great sounding circuit!!

Thanks again for all your help, I'm sorry I wasted your time!

Wade

[anchovie]

Don't worry, we all do something like that at some point!

[B Tremblay]

I'm happy to hear that you successfully debugged your build!

[oldrocker]

Great.  I knew you would figure it out.  Ok it's going to be my turn to try this project soon.