GGG Boutique Bender debugging

Started by stezza, January 19, 2011, 05:55:03 AM

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stezza

Hi All,

I'm building the Boutique Bender (tonebender mKIII / Soulbender clone) from General guitar gadgets.

Schematic link:
http://www.generalguitargadgets.com/diagrams/tb3bb_sc.gif?phpMyAdmin=4a28f86a515b7883e7bc35a68d4e7b6d&phpMyAdmin=78482479fd7e7fc3768044a841b3e85a

Using this vero layout:
http://www.diystompboxes.com/smfforum/index.php?topic=80871.0

I have breadboarded it previously and tweaked to my liking.
Part substitutions:
R7: 500k pot
R8: 10k
R14: 2M2 (huge I know, but needed this to get my Q3 collector to ~4V on breadboard - sounded good also)
R15: 1M pot
C2: 220pF
C6: 0.22uF

I have used an audioprobe, and the signal goes all the way through, it is quite a bit quiter and a little fuzzy. not sure what this means.

My voltages

Battery: -8.81

Q1
C=-1.80
B= -1.76
E= -1.66

Q2
C=-1.80
B=-1.66
E=-1.75

Q3
C=-236mV
B=-120mV
E= 0V

I also was following voltage through the circuit to try and find a fault

Voltage at R9 before= -8.81 after=-4.51
at R8 before = -4.51 after= -238mV
C6 before= -4.51 after= 0V

Not sure what this means, but I remember on my breadboard the voltage after R8 was approximately 4V.
I even replaced these parts and checked all of the solders for cold joints or unintended earthing.

I've checked my polarized caps and C3 is -8.81 at anode, 0 at cathode, C5 is -1.75 at anode, 0 at cathode.

I'm out of ideas :/ It was working nicely on the breadboard so it must be something stupid I am doing wrong...
I have run earths from the board, volume 1 and the battery all to the input jack sleeve.

Stezza
   

twabelljr

#1
Not sure about transistor voltages (Q1 and Q2 collector voltages seem low) but capacitors block dc voltage so it is normal to read zero volts dc after a cap. Battery voltage is a little low. Same components you used on breadboard?
QuoteCapacitors are widely used in electronic circuits for blocking direct current while allowing alternating current to pass, in filter networks, for smoothing the output of power supplies, in the resonant circuits that tune radios to particular frequencies and for many other purposes.

Shine On !!!

stezza

Yea same components.

Correction I am using a 1M resistor instead of 2M2. On my breadboard this gave me a Q3 voltage of 3.5V to 4.5V. Will check my offboard wiring as I think it may be an earthing problem.