dr boogey debug

[elfen]

I did the veroboard version of the dr boogey. I really took my time doing it, measuring components twice before soldering, verifying 3 times I was about to solder it at the right place. Reverified positions 3 times before posting.
I did and audio probe, here is what I get:

http://k003.kiwi6.com/hotlink/06e7obuew7/boogey.mp3

what you ear is, with every knob fully open and a cab sim:
-output of guitar
-output of dr boogey
- Q1 Drain,Q2 Drain,Q3 Drain,Q4 Drain,Q5 Drain
-gain pin 2

1.What does it do, not do, and sound like? not much gain, lower output than the output of the guitar

2.Name of the circuit :dr boogey veroboard version

3.Source of the circuit : http://www.sabrotone.com/wp-content/uploads/2010/04/DrBoogey.gif

4.Any modifications to the circuit? N

5.Any parts substitutions? Y, C8=20nF instead of 22nF, C17=33nF instead of 30nF, 22nF caps are ceramic instead of film-box

6.Positive ground to negative ground conversion? N

7. What is the out of circuit battery voltage? =>8.51V

Voltage at the circuit board end of the red battery lead =8.47V

Voltage at the circuit board end of the black battery lead =0


Q1
D =5.06
S =2.39
G =0

Q2
D =5.07
S =2.36
G =0

Q3
D =5.02
S =2.62
G =0

Q4
D =5.03
S =2.35
G =0

Q5
D =7.88
S =7.36
G =5.11

D1
A (anode, the non-band end) =0
K (cathode, the banded end) =8.41

Let me know if you have any hint of where the problem might come, or if  any other voltage/audio probe would help

[PRR]

Voltages on Q5 are wrong.

Squinting the stripboard layout, wiring around Q5 don't look right to me.

However it seems others have built from that site?

Is there a schematic? (Not just a layout.)

[elfen]

Comparing with gaussmarkov schematic ( http://gaussmarkov.net/layouts/drboo/drboo-schem.png ) I don't see anything wrong around Q5.
some people where successful with it: http://www.sabrotone.com/?p=1891

Currently trying to bypass every pot.

[elfen]

and just to be sure, for the treble pot (supposed to be 25k), I used a 50K pot with a 50k resistor going from pin 1 to pin 3. anything wrong with this?

[elfen]

changed Q3 and Q5, nothing changed

[PRR]

Trim TRIM4 to get +5 Volts at Q5 Source.

Yes, this will put Q4 Drain below 5V; I think with these FETs Q4-D needs to be low enough so that Q5 S is not slammed to the +7.88V rail.

[elfen]

tried it, all it did was lowering the output.

[Govmnt_Lacky]

and just to be sure, for the treble pot (supposed to be 25k), I used a 50K pot with a 50k resistor going from pin 1 to pin 3. anything wrong with this?

I dont think this is CAUSING your problem however,

I do not think you can do this to a LOG pot and get the same results. People often do the same trick for the MIDs pot (tie a 5.1K resistor across a 5KB pot lugs 1 &3) but that is for a LINEAR pot.

I don't think the same trick will work with a Log pot 

[elfen]

i knew it might change the feel of the knob, but that's all i had in hands so I taught  at worst i could change it when done with the pedal.

But, judging by the shematic, if I take the output from Q5 source directly, I'm bypassing the eq section, and it still doesn't sound right.

Don't know if i'm right. but, judging by the sample I uploaded (http://k003.kiwi6.com/hotlink/06e7obuew7/boogey.mp3). Q1 and Q2 do amplify and add a little distortion (and Q4 and Q5 stage seem to be working), but the output of Q3 is lower and adds no distortion. I assume the problem must be somewhere between Q2 and Q3, but can't figure it out.

any idea are welcome

[ubersam]

try sticking a dc blocking cap between Q4 & Q5

[elfen]

placed a 2.2nF cap just before Q5 gate. After redoing bias, I have now:
Q5 D=7.74 S=7.18 G=0
It's a bit like if tone was "there" but with some mega lack of distortion.

by the way, I took pictures of top and bottom of my circtuit compared line by line with the vero layout, everything is the same, so no mistake here.

any help still greatly appreciated!