help with E.H. muff fuzz or how to bias 4558

[dansamp]

ok i give up    UNCLE!!!!!

i am having trouble with my latest project
i built a muff fuzz 'cause i thought it would be easy since i had most of the parts lying around

it sounds terrible it has the symptoms of having the opamp improperly biased
if i hit the strings hard it sounds blatty and very distorted
i have checked and rechecked my wiring i am using the strip board layout in the gallery  i can not find the schematic nor can i find out how to bias the opamp
please help
here are my voltages :

1. 4.31 vts
2. 4.69 vts.
3 4.16 vts
4 .0 vts
5. 9.27 vts
6. 4.74 vts.
8. 4.52  vts

i am not sure of the pin out of the opamp
it is a 4558

#1 starts with the dot and goes down from there
#5 is opposite the dot and goes down from there


any help would be greatly appreciated




thanks in advance


dan................... :roll:

[darkseid]

Im not sure, but i think its this one below.

http://www.harpamps.com/schematics/mufffuzz.pdf

[octafish]

Sorry I can't be of much help, but I can offer this-
http://wwww.ges.cz/sheet/r/rc4558.pdf
also whose layout is it? Is it Dragonfly's?

[aron]

There are problems there:



Here's your pinout and pin 8 should be your 9 volts.

Pin 5 and 3 should be 1/2 V+ or approx 4.5V.

First, figure out why pin 8 doesn't have 9 volts as it should be directly connected to V+.

[dansamp]

it does have 9 vts.
but as i stated i did not know the pin out of the opamp
so i listed
8.
7.
6.
5.
as
5.
6.
7.
8.
:?:

thanks for the schematic and info re; the opamp
does anyone know what the other voltages should read???

thanks ...........

[aron]

Yep,

Here:

http://www.diystompboxes.com/pedals/debug.html

links to here:

http://www.geofex.com/fxdebug/fxdebug.htm

and finally here:

http://www.geofex.com/fxdebug/bias_prob.htm