Bloviator doesn't work

[Gialli]

Hi everyone,
I've just built a Bloviator (etching the pcb) and it doesn't work. To find the problem I connected the output wire of a test rig on every components following the signal path from IN to OUT and on the output of the first input stage (Pin 1 of tl072) the sound breaks down, so I think there is the problem. The conductive tracks and components values are ok.
Here are the voltages on the Ics' pins

TL072
1 - 1.39
2 - 1.39
3 - 0.88
4;5 = 0
6 - 6.08
7 - 7.17
8 - 7.83

TL074
1 - 1.39
2 - 1.39
3 - 0.91
4 - 7.79
5 - 3.48
6 - 3.52
7 - 2.15
8 - 7.03
9 - 2.10
10;11;12 = 0
13 - 6.87
14 - 7

TL071
1,2,4,5,6,8 = 0
3 - 3.87
7 - 7.8

Here are the photos of top and back of pcb and a little video to explain my problem better.

http://it.tinypic.com/r/20pu70o/5

[madbean]

Your supply voltage is quite low at 7.8v. Are you using a regulated 9v supply or fresh battery? If so, something is sinking your voltage...perhaps D1 is faulty.

As far as the tracks, have you tried a continuity tester to be sure? Specifically, I would look at making sure there is no continuity between the R4 pads and the ground plane, plus C3 and its adjacent tracks.

[Gialli]

Your supply voltage is quite low at 7.8v. Are you using a regulated 9v supply or fresh battery? If so, something is sinking your voltage...perhaps D1 is faulty.

As far as the tracks, have you tried a continuity tester to be sure? Specifically, I would look at making sure there is no continuity between the R4 pads and the ground plane, plus C3 and its adjacent tracks.

Thank you for reply, but unfortunately it doesn't work yet. I changed D1, controlled that there's no continuity between the r4 pads and ground and C3 and its adjacent tracks, the battery was fresh but I used a regulated 9v supply anyway, and with the power supply came out a 100 Hz signal. The voltages on the pins are rights? If not, can I know the voltages they should have?

Ps. With the battery, the voltage on 9v pin is 8.34 and the voltage drop on the diode is 0.74V. I think it's fully conducting, or not?

[madbean]

Voltages are completely off. IC3 seems to be the main culprit. Pins 2 and 6 should have about the same voltage as pin3. On yours, you have 3.8 going in and 0v going out. Ideally you would have about a 9v supply on pin7, about 4.5v on pin3 and then the same 4,5 output on pin2 and 6.

I would remove D1 first. Put a jumper there. Now reflow all the solder joints around IC3 and check again for solder bridges. Run a small utility knife between the traces. A bridge can easily escape the human eye but still be there.

[Gialli]

Ok, I fixed it, thank you very much for your help Brian! Pin 2 and 6 went to 0 V because there was a tiny tiny tiny drop of solder between the pin 10 of TL04 and ground track. I've been so stupid because that was a problem that I could see from the schematic, infact pin 6 of TL071 gives the voltage reference Vb, and it cannot be at 0V