Ross compressor (tonepad) static sound problem

[bent]

Hi,

my ross build from tonepad http://tonepad.com/getFile.asp?id=9 is doing a strange sound.... in the background there's some sort of static doing morse code.....
mod made: variable recovery at fuzzcentral
power supply regulated and filter

the "static sound" is going away when sustain pot is at minimum or guitar volume is down. 

i try to solved the problem by putting a cap from pin6 of ca3080 to ground, and bigger the cap was (start from 0.001 up to 2.2uf ) ,the static went away but the guitar sound too....  can't find a middle spot...

anyone have a clue to where else to look...    ?

thank's
bent

[MikeH]

My guess is you've got something going on in the 'pre-compression' part of your circuit and that noise is getting amplified.  I'd post voltages- do the whole "DEBUGGING: what to do when..." thing.

[bent]

voltage:

ca3080:
1- 0
2- 4.41
3- 4.39
4- 0
5- 0.67
6- 2.23
7- 8.87
8- 0

Q1:
0.76
1.25
8.08

Q2:
1.7
2.22
7.22

Q3:
0
0
7.75

Q4:
0
0.02
7.73

Q5:
7.27
7.73
8.87

THANK'S
BENT

[MikeH]

For your Q voltages could you label which voltage corresponds to which pin? ie CBE?

[bent]

E
B
C

sorry 

bent

[MikeH]

Somethings fishy with Q3 and Q4; check orientation or for solder bridges/bad joints/etc in that neighborhood.

[ayayay!]

Are D2 & D3 oriented properly?

[bent]

Problem found.....

i just found out that the problem wasn't the compressor, it's come from the guitar, cause i have the same static sound when i put my distortion whitout the compressor...
i change the volume pot few weeks ago, and i put a alpha pot 16mm, i think the pot might not be good...i'll try to find a real volume pot and change it to see if this is the problem...

thank's every one....

bent

[JDoyle]

Before you think it is 'solved'...

- Some of your voltages are kind of screwy - your V+ is all over the map on different parts: 8.87 on the chip and Iabc drive transistor (Q5), 7.7 on the rectifying transistors (Q3 and Q4), 7.2V on the phase splitter/output transistor, and 8V on your input transistor.
- The input transistor is really weird - the base should be biased to 2.8-2.9V (27k/56k+27k * V+ = Vbias, 0.325*8.87=2.88V) but yours is at 1.25V. Yet the base-emitter diode is just barely forward biased at 0.5V.
- elsewhere it looks like your bias voltage is 2.22 - a full diode drop smaller than the 2.8 that it should be.

If it works, it works. However, there do appear to be some issues with your circuit.

Regards,

Jay Doyle