Sansamp GT-2 DIY debug - no sound

[Rethfing]

Here's the schematic and PCB layout:
http://www.tonepad.com/getFile.asp?id=112

When I plug it in it gives no sound apart from constant squeak which is getting louder when I roll the Volume up. I've checked all ground connections - they're fine. I also measured all voltages:
IC1:         IC2:         IC3:
1. 3,57     1. 1,36     1. 1,98     1. 3,57
2. 3,57     2. 9          2. 1,98     2. 3,57
3. 3,24     3. 3,53     3. 2,07     3. 3,57
4. 0          4. 0         4. 0          4. 0
5. 3,24     5. 1,36     5. 1,96     5. 3,57
6. 3,56     6. 1,78     6. 1,86     6. 3,57
7. 3,57     7. 1,42     7. 1,86     7. 3,57
8. 9          8. 9         8. 9          8. 9

2N5088:
E: 2,98
B: 3,57
C: 8,99

I was looking for some solder bridges but I couldnt find any, so I suspect broken part. Can anyone give my a guide how to audio-probe this stuff?

[Govmnt_Lacky]

From the voltages you posted, you have quite a few issues...

- All of the IC pins 1, 2, 3, 5, 6, and 7 should be around HALF of your voltage on pin 8 (4.5V)
- Your voltages on IC2 and IC3 are WAY off. Even farther off than IC1 and IC4.
- On IC2, you have 9V on pin 2. Definitely a short causing that. Whether it be a trace, jumper, or internally shorted IC.

Look over these issues (especially the 9V on pin 2 of IC2) and report back.

Good Luck 

[Rethfing]

The first thing that I noticed is that I have a connection between 1st pin of IC1 and the pin above it. Like in the image, green marking shows the pins, orange line shows scratch:


I scratched it very hard but my ohm-meter still shows there's some connection. I dont see any place where these two pins are connected.

P.S. Oh, the image is mirrored to the original because it was a print to help me trace the board.

[Govmnt_Lacky]

Remove the IC and recheck with your meter. You need to ensure there IS NOT a direct short between those points.

Don't forget to take a GOOD look at IC2 Pin 2. Definitely something wrong there.

Good Luck 

[Rethfing]

Ive found a connection beetwen the jumper and 220pf on the side of pin 5! Voltage seems ok now, off we go for testing!

[Govmnt_Lacky]

If that does not work, or you are still having problems...

I think we have established that there MAY be some soldering issues. I recommend getting a magnifying glass and tracing the ENTIRE board for solder bridges and/or shorts.

Don't worry... you will get there!!!

Good Luck and let us know how it turns out 

[Rethfing]

It works! Yaahaa Thanks a lot for your help! Its awesome

[Govmnt_Lacky]

Awesome!!!

Have fun!!! 

[Rethfing]

Hmm.. it seems that my bass pot is not working.. I've already tried different one. All the solder joints seem fine around that part of circuit. Anyone have any suggestions?

Dont bother, I just realised that I've put 220nF in place of every 22nF :/ replacing now.