vox wha very "thin" and at very low volume

[paulossant]

Hi, i have a very old crybaby gcb-95 so i ripped his guts and put a new pcb, resistors, capacitors, trannies, jacks, switch and inductor(yellow fasel), but it won't work(bypass is fine, but when i turn it on i hear the wha effect, but at a very low volume, after two weaks trying all, the problem continues.
I have checked all the resistores, inductor, jacks, the wires and solder points..

here it goes the usefull information:

tru-bypass is fine, effect very "thin" and at very low volume
vox v847 wah
Source of the circuit: http://www.electrosmash.com/vox-v847-analysis
PCB boughted :http://www.moutoulos.com/eShop.php?view=productPage&product=6&category=2
No modifications to the circuit
everything is brand new except for the pot and the enclousure
Voltage at the circuit board end of the red battery lead = (haven't measured it yet)
Voltage at the circuit board end of the black battery lead = (haven't measured it yet)

My voltage values:

Q1
C = 2.0V
B = 1.4V
E = 0.1V

Q2
C= 8.7V
B= 7.9V
E= 2.2V

Inductor = 1.38v
------------------------------------------------------------------

The desired values for this circuit are

Q1

C = 4.48V
B = 0.72V
E = 0.1V

Q2

C = 8.7V
B = 3.9V
E =  3.3V

inductor = 0.722V

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The only thing i haven't tried is switching the C1,C2,C4,C5.. does anybody suspect the capacitors?

any help is welcome

[PRR]

Welcome!

> Voltage at the circuit board end of the red battery lead = (haven't measured it yet)
> Voltage at the circuit board end of the black battery lead = (haven't measured it yet)

Why not?

> Q1
> B = 1.4V
> E = 0.1V
> Q2
> B= 7.9V
> E= 2.2V


Well, that can't be right. B-E difference "has to be" near 0.6V. You got twice that. Or more.

Wrong transistor.

Wrong transistor pin-out. (Note the GP board faces the transistors two different ways.)

Bad connection.

Mis-reading your meter.

[paulossant]

i thought that the transístores i had put in the first place ( bc108b) were broken, so i changed them for two (bc109c) and tripled checked the transístor pin-out and if they match the pin out needeed for the board, but the problem continues the same.. i have re-wired all the cables to ensure a good conection... can't possible be the capacitores?

[PRR]

Perhaps if you can take clear pictures of your build, some sharp-eye person here will see a problem.

[paulossant]

i've solved the problem throwing the pcb to garbage.. it must contained some error in the design or i had gotten a pcb with some trace cutted(one can't view the traces because them are inside the double layer of the board).

The quality of the board was good but things like this can happen to anyone making them..
I had put the old pcb in the wah case and switched the components for the ones i had boughted and... it worked like a charm! (two trimmer's for the 33k and 510ohm resistors, true bypass mode without the input buffer and a yellow fasel. best wah sound i ever had!)

thanks for the help

[strassercaster]

man nothing solves more problems than the shit can . ha ha.