Tonepad tubescreamer - no output

[twabelljr]

With output it seems there is a problem in the clipping section. No power to board and refering to the Tonepad layout you linked to earlier if you set your DMM on diode test and touch the red lead to pin 2 of opamp and black lead pin 1 you should measure the turn on voltage of D1 (one diode drop). Reverse the leads,  red on pin 1 and black on pin 2 you should measure the turn on voltage of D2 and D3 (two diodes drop or approx. double your first reading unless you have D3 jumpered then one diode drop).  If that checks ok set your DMM to ohms and touching one lead to pin 2 and the other to the right side drive pad you should measure 51k ohms. Then from the right drive pad to pin 5 of opamp should  read 1k ohms. Make sur the traces between opamp pins 1 and 2 are not shorted together. If all is ok to this point remove the drive pot and substitute a 500k or 1meg resistor across the left and right drive pads at top of layout. If none of this leads to fix then I am stumped. (I hope I am correct with deciphering this layout) Best of luck! Add: I believe if you measure the resistance between pins 1 and 2 it should be no less than what a diode reads with your DMM on the ohms scale. If it is less I would suspect a short. I also think it should change as you rotate the drive pot.

[tasos]

try this....use a resistor from battery to the circuit's power...this would drop your voltage a little...try a 4.7k resistor or a pot....it has worked for me in anoher circuit..

[twabelljr]

Regarding above recommended measurements, remove the opamp from the socket. I don't think a high impedance DMM will damage it and I am not sure if the opamp will affect your readings so better safe than sorry right?!

[notid]

Thanks  for all of the ideas!

Results: .536/.538 with leads on pins 1&2. Seems correct, as I am using symmetrical clipping.

pin 2 - right side of drive pot = 49k  = seems correct.

pin 5 - *left* drive pad = 1k = seems correct. (I figured you meant left here based off the schematic).


I didn't do the last bit since I tested the drive pot and it seems to be correct (range o 1k-450k).

Major bummer. Any other ideas?
Bryce

[twabelljr]

(I figured you meant left here based off the schematic).

Oops!, sorry I did mean left. You caught my mistake. I was tracing out the clipping section on a printout trying to be discreet while at work. Like I said in my message I will take some measurements from my T.S. and see if I can come up with anything more helpful. So let me ask this again just to be clear on your issue:
With pedal engaged:
                            --you have boost or cut that responds to the volume control
                            --the tone control does change the tone as you turn it from low to high and high to low
                            --you do NOT have clipping that responds to the drive control  

I tested the drive pot and it seems to be correct (range o 1k-450k).

Did you check the drive pot range from the pads it is soldered to on the circuit board? (Silly question maybe, sounds like you know what you are doing)
This is a verified layout, I was hoping to hear more ideas from people who actually built the same pedal as you. Mine is a modded factory TS-9 but maybe I can help. I will crack her open when I get a little spare time. Hopefully soon.

[notid]

(I figured you meant left here based off the schematic).

Oops!, sorry I did mean left. You caught my mistake. I was tracing out the clipping section on a printout trying to be discreet while at work. Like I said in my message I will take some measurements from my T.S. and see if I can come up with anything more helpful. So let me ask this again just to be clear on your issue:
With pedal engaged:
                            --you have boost or cut that responds to the volume control
                            --the tone control does change the tone as you turn it from low to high and high to low
                            --you do NOT have clipping that responds to the drive control  

I tested the drive pot and it seems to be correct (range o 1k-450k).

Did you check the drive pot range from the pads it is soldered to on the circuit board? (Silly question maybe, sounds like you know what you are doing)
This is a verified layout, I was hoping to hear more ideas from people who actually built the same pedal as you. Mine is a modded factory TS-9 but maybe I can help. I will crack her open when I get a little spare time. Hopefully soon.

Correct to all 3 questions. The drive pot is doing something (subtle level changes), I'm just hearing no clipping. Could it be that my opamp is malfunctioning? I only have one of that IC, so I haven't tested with another one.

I will triple check the drive pot range and get back to you.

[notid]

Checked the pot on the circuit board. 1-400k ohms.

Would a photo help here? The solder side is getting uglier and uglier each time I remove a component to test. I'm also ordering a few 4558 chips from smallbear, since I'm wondering if this one is malfunctioning.

I'm wondering if this is one of those times when it's best to just start over.