My Micro amp build thinks it is a fuzz!

[Woolly Mother Mammoth]

I have talked about this in one of my other threads (http://www.diystompboxes.com/smfforum/index.php?topic=97122.0). I figured this needed to have it's own thread since it became a bit of topic.

I built a Micro amp (schematic and layout from GGG) with some substitutions here and there. The thing is it is acting like a very gated fuzz right now and I do not have a clue why?


I substituted the following original parts.

1. R1 & R2 10 & 22Mohm >1Mohms
2. R6 2.7K >3.3k
3. C2 47p >150p
4. C5 15Uf >22Uf
5. D1 1N4001 >PR1507
6. 500k Rev Log>500k Lin






I'm using an analog multimeter so it will not be exact measurements, but good enough I guess.

TL061CN:
1=  0
2= 8.6
3= 3.8
4= 0

5= 0
6= 0.5
7= 2.5 - 2.8
8= 0



PR1507 Diode:
A: 9.90
K: 8.33


Schematic
http://www.generalguitargadgets.com/pdf/ggg_mamp_sc.pdf?phpMyAdmin=78482479fd7e7fc3768044a841b3e85a

Layout
http://www.generalguitargadgets.com/pdf/ggg_mamp_lo.pdf?phpMyAdmin=78482479fd7e7fc3768044a841b3e85a

[deadastronaut]

not sure on that diode....

that diode is only there as a reverse polarity protector.......(measure your voltage coming out of that diode make sure its 9v..if its not, lose it.)..

as for values, they are there for a reason...you can sub values, but  not with a massive difference..good luck.

you should have 9v on pin 7...

[Woolly Mother Mammoth]

Whoopsie! It was missing the connection between R8 and C4, no wonder it was all fuzzy and super gated.

What a waste of space this thread became, sorry.

[deadastronaut]

sorted!...

you should still have 9v on pin 7 though....

[Woolly Mother Mammoth]

sorted!...

you should still have 9v on pin 7 though....

Now I got:

(TL061CN)
1=  0
2= 4.2
3= 0.4
4= 0

5= 0
6= 4.2
7= 8.3
8= 0

[deadastronaut]

you should also have 9v on pin 5 going by that layout also...see where the 9v goes?.........

check it over with a meter...follow that voltage trace on the pcb....

[Woolly Mother Mammoth]

But.. pin 5 is not even supposed to be wired anywhere?? Confused?

Either way it boosts the volume now, some where around 10 db+.

[bluebunny]

Won't there be a small voltage drop across the diode that would account for <9V at pin 7?

[deadastronaut]

whoops misread the layout...on the pin 5...

[Woolly Mother Mammoth]

whoops misread the layout...on the pin 5...

No problemos!

Won't there be a small voltage drop across the diode that would account for <9V at pin 7?

Yeah, I better replace that diode. I get small amounts of distortion when the pedal is cranked, figure it is due to the lack of voltage.