Well, here we go.... or, "it don't work."

[Celery_Strat]

I tried my hand at a pedal using the tonepad tube screamer clone.  I have it built, wired, and in the box.  When it's off, the guitar can be heard as usual.  Turn it on, and the LED lights, and it goes silent.  No hum, no buzz, no nothing.  I've checked for bad joints and the usual mechanical problems.  I was wondering if this might be a "oh yeah, that's usually because ______"  kind of problem.  Maybe you guys can help me get it going.  She's a beauty, but right now, she's a doorstop with a light...

THanks

[Quackzed]

ive seen a few threads where the layout wasnt reversed to the bottom of the pcb and the pinout of the chip was backwards due to this...
check the pinout... also check the pinout on the transistors, what ic and transistors you used , any weird parts... check for board to box shorts...

[Celery_Strat]

Well I'm pretty sure the layout is correct.  All parts are as called for value wise, except for a 25k tone pot instead of a 20k.  and the .22uF caps are film instead of tantalum. 

[Taylor]

Aron has kindly made a link just for such an occasion! 

[oldschoolanalog]

...and Mr. Livingston has kindly provided a road map!
The good news is when something doesn't work at all it's usually some simple oversight or a DOH! moment.
Usually.
It's intermittent problems that are the the real pains in the keyster.

[Celery_Strat]

The schematic / layout can't be linked to, but it's at tonepad.com. It's the tube screamer.pdf.  The wall wart is fine, although it's voltage is a little high.
I used TS-808 specs, only changes are the .22uF caps are film instead of tant.  The tone pot is 25K instead of 20k.  

Q1
E 4.37
B 3.62
C 16.9


Q2
E 4.40
B 3.64
C 16.9

RC4558

1= 2.27
2= 2.15
3= 6.42
4= 0
5= 2.66
6= 2.18
7= 2.17
8= 17.08

D1
A 2.16
K 2.28

D2
A 2.28
K 2.16

D3
JUMPERED PER LAYOUT

Thanks

[blooze_man]

Are the electrolytics rated for that high a voltage?

[Jhouse]

Is this the layout?

Anywho, you should not be getting that high of voltages (pin 8 of the IC and the C leg of both transistors are connected directly to the power supply). You're using too strong of a power supply. What are you powering it with? It should be running at 9 volts.

Try turning the power down to 9 volts first. If the pedal doesn't work after that, check the voltage ratings on your parts. If their rating isn't more that 18, chances are that you fried them. Maybe not though. See how adjusting the power works for you first.

[petemoore]

  There's a well yea, and it's cause there's wide variety of possibilities, we're narrowing them down.
 Fair to assume PS is 16.9 or so also, which raises the question what is the rating of the capacitors, in particular the electrolytics.
 Although "HV" operation alters the circuit to some extent, all of the components are available in the higher ratings, so as long as none of them are overvoltaged or "AC'd'', 17vdc can work.
 A 7812 12v voltage regulator chip may be tried along the way.
 Starting with 9vdc battery isn't a bad idea, after checking +/- has no short.
Q1
E 4.37
B 3.62
C 16.9
 B/E diode: Base needs to be one B/E diode drop above emitter, check that the '510k' actually goes to the voltage divider resistor junction [two equal value resistors strung across the +/- rails] and that they are =, providing a 1/2v reference for bias.
Q2
E 4.40
B 3.64
C 16.9
 Often a common problem is a common solution, these transistor buffers are identical, both have common route to the Vbias reference.
 Measure the emitter resistors, the collectors seems connected to a supply that is guessedly approximated to be 16.9vdc or a little more.
RC4558
1= 2.27
2= 2.15
3= 6.42
4= 0
5= 2.66
6= 2.18
7= 2.17
8= 17.08
 This has Gnd. and has V+ [must be typo or the transistor collectors and pin 8 aren't common]. So the supply rails look connected and the inputs and output pins for each opamp are...offbias. These bias's are also referenced to/have resistor to Vbias [like the transistor bases].
 Measure the voltage and resistances of the voltage divider resistors, if using 16v capacitors they've been overvolted and toss them.

[Celery_Strat]

Wow....  maybe I'm not ready for this....  Anyway, the caps are all 35v and above.  corrected the voltage to 10vdc. 

[Jhouse]

(9 would still be preferable, but I think it might be fine) I don't think you'll have to replace anything then, maybe. I'm not sure about the transistors or the IC. Did you have any luck with it now?

[Celery_Strat]

Nope.  Completely transparent when "off".  Dead silent when "on"...   I have noticed that in most of the stories involving this design, the two .1uF caps (labeled "NP") look like the ones in this pic.   Mine are just regular film caps.  (think sprague) Would this matter?

[Jhouse]

.1uf NP caps? Was that a typo? They should be 1uf.

What are you voltages now that you have brought down the power supply?

[twabelljr]

Removed for Doh! factor

[Celery_Strat]

Sorry, I meant 1uF NP.  As seen on the schematic.  I was under the impression film caps were not polarized. 

Q1
E 3.20
B 2.79
C 10.6


Q2
E 3.20
B 2.79
C 10.6

RC4558

1= 1.97
2= 1.88
3= 4.89
4= 0
5= 2.24
6= 1.88
7= 1.87
8= 10.6

D1
A 1.88
K 1.97

D2
A 1.97
K 1.88

D3
JUMPERED PER LAYOUT

[Schappy]

All beginners must learn to use an audio probe.

[Taylor]

I agree - audio probing is a much more intuitive and quick way to diagnose a problem than measuring voltages IMO.

[Jhouse]

Removed for Doh! factor

If I had a dollar for every time I had one of those moments... .

I was under the impression film caps were not polarized.

They aren't. I had a "doh" moment too.

D3
JUMPERED PER LAYOUT

I noticed that I didn't see a jumper in the picture. That might make a difference.

Read Petermoore's post and check the things that he said in there. His advice is exactly what I would tell you. Also, an audio probe would help out quite a bit.

[Celery_Strat]

Mine is jumpered.  The pic is one i found to illustrate the different appearance of the 1uF "NP" caps.   Building an audio probe now...

[twabelljr]

Yeah, it needs to be jumped to complete the D2 circuit. Nice board pic. Can you post one of the back and maybe offboard wiring?