Snow White Auto Wah, no signal through board. Please help.

[Vic01]

Hi all, long time lurker, finally plucked up the courage to try my first simple build, a Bazz Fuss. It worked fine once I found a faulty bridge. Inspired I was, and boldly set out to build a Mad Professor Snow White Auto Wah.
http://tagboardeffects.blogspot.com/2013/04/mad-professor-snow-white-autowah.html

Signal is fine with bypass. Absolutely no signal through circuit board.

Parts substituted:
7K9 resistor replaced with 8K2
Q1 2n5457 with 2n5485

Wired up as positive ground.

Tried battery with guitar. Now using bench power supply to trouble shoot.

Have double checked for correct components. Found and replaced one res and one cap.

Triple checked component layout, links and cuts.

Quadruple checked orientation of caps, diodes, VR.

Used magnifying glass to check for false bridges and cold solder joints.

Of note is that the voltage on the input side of the resistor 47R which is second to D2 just in from 9v power, measures 8.19 volts, whilst the output side measures 1.13 volts. Replaced it, did the same thing.

Following are voltage measurements, with 9v from the power supply.

Q1
D = 1.16
S = 1.14
G = .24

Q2
C= .16
B= .28
E= .29

IC1
P1 .26
P2 .30
P3 .66
P4 .54
P5 .78
P6 1.13
P7 .78
P8 .30
P9 .21
P10 .63
P11 0
P12 .63
P13 .50
P14 .49
P15 .28
P16 .26

IC2
P1 .24
P2 .28
P3 .47
P4 0
P5 .30
P6 .47
P7 .47
P8 .35
P9  6
P13 .33
P14 .25

D1
A = .05
K = 1.13

D2
A = 8.93
K = 8.19

D3
A = .31
K = .24

D4
A = .24
K = .15

D5
A = .24
K = .29

Thanking you all in advance.

[Alex]

Hi Vic.
The pinout of the IC should be:

1   14
2   13
3   12
4   11
5   10
6   9
7   8

Have you measured the value of your 47R resistor before soldering it?
You can try to jump its two legs and see what happens...

[Vic01]

Hi Alex, yes, I measured the resistor out of the board and it measured fine. I even replaced it with the same value with the same result.

I did as you suggested, I jumpered the resistor and the bench power supply reacted as if it had detected a short cicuit.

On Wed, Jul 11, 2018 at 6:14 PM, Alex [via Guitar FX Layouts] <[hidden email]> wrote:

Hi Vic.
The pinout of the IC should be:

1   14
2   13
3   12
4   11
5   10
6   9
7   8

Have you measured the value of your 47R resistor before soldering it?
Try to jumper its two legs and see what happens...

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[Vic01]

And yes, that is the sequence of pins that I measured. Anti clockwise from pin 1 (Left of semi circular notch)

[Alex]

Ok.
Your values are all wrong (IC2's pin 4 should be close to 9V) therefore there must be a mistake or a short somewhere. Possibly in the voltage regulator rows.
Do you have high quality back and front pictures of your board?

[Vic01]

The voltages sure are wrong. Here's a couple of pics. Soldering is not pretty but there are definitely no false bridges and I can't see any cold solder joints. Although I did go over a couple just in case.

The anomaly with this build is that I am image dyslexic, so when I made the cuts to the bottom of the board, I though I was being smart when I 'flipped' the orientation of the board. But when I installed the links and the components I realised I had it arse about. But I diligently and painstakingly tried to ensure that all the componentry was still in the correct position and orientation.

But perhaps I am kidding myself and should start from scratch?

[IMG]<a href="http://i278.photobucket.com/albums/kk96/vicval01/Board%20Bottom_zpsweygxe3a.jpg[/IMG]">http://i278.photobucket.com/albums/kk96/vicval01/Board%20Bottom_zpsweygxe3a.jpg[/IMG]

[IMG]<a href="http://i278.photobucket.com/albums/kk96/vicval01/Board%20Top_zpskzzppkrw.jpg[/IMG]">http://i278.photobucket.com/albums/kk96/vicval01/Board%20Top_zpskzzppkrw.jpg[/IMG]

On Wed, Jul 11, 2018 at 9:47 PM, Alex [via Guitar FX Layouts] <[hidden email]> wrote:

Ok.
Your values are all wrong (IC2's pin 4 should be close to 9V) therefore there must be a mistake or a short somewhere. Possibly in the voltage regulator rows.
Do you have high quality back and front pictures of your board?

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[Alex]

Ok. That explains. Everything is reversed.
In theory, if done carefully, with those types of ICs it sholdn't matter.
The main problem (pictures are not very clear) is that you've also inverted V+ and V- on both of them.
I think restarting from scratch may be the easiest solution.

[Vic01]

Yeh, that makes sense. I'll have another crack. Thanks. :)

On Thu, Jul 12, 2018 at 3:38 PM, Alex [via Guitar FX Layouts] <[hidden email]> wrote:

Ok. That explains. Everything is reversed.
In theory, if done carefully, with those types of ICs it sholdn't matter.
The main problem (pictures are not very clear) is that you've also inverted V+ and V- on both of them.
I think restarting from scratch may be the easiest solution.

---

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