GGG tuned muff HELP ASAP

Started by wildebelor, April 08, 2014, 04:20:18 AM

Previous topic - Next topic

wildebelor

So I'm on a little deadline and here is my problem.

I've built TWO of these muffs today and one works, the other doesn't.

Here is the schematic: http://www.generalguitargadgets.com/pdf/ggg_bmp_ggg_sc.pdf?phpMyAdmin=78482479fd7e7fc3768044a841b3e85a

I've boiled it down to a problem at Q1 where B and E aren't reading and C is 9V
All resistor values are the same, caps are the same, everything seems fine.
I'm absolutely stumped and I need some help asap so I can pass these pedals on.

I've never been so frustrated in my life! I swear I've exhausted all possibilities and I know its going to be something very simple that I overlooked  >:(

Thank you in advance!

I can't think of anything funny just yet.

samhay

What does 'aren't reading' mean?
I'm a refugee of the great dropbox purge of '17.
Project details (schematics, layouts, etc) are slowly being added here: http://samdump.wordpress.com

wildebelor

they are meant to have values however they are both 0.00

for example Q1 is meant to read as follows
E 0.03
B 0.6
C 3.9

but it actually reads like this
E 0.00
B 0.00
C 9.00
I can't think of anything funny just yet.

deadastronaut

triple check your resistor values around Q1...i know its obvious, but its easily done.

and check for tiny solder bridges
https://www.youtube.com/user/100roberthenry
https://deadastronaut.wixsite.com/effects

chasm reverb/tremshifter/faze filter/abductor II delay/timestream reverb/dreamtime delay/skinwalker hi gain dist/black triangle OD/ nano drums/space patrol fuzz//

wildebelor

All values are correct and no solder bridges!  :o
I can't think of anything funny just yet.

samhay

OK, they are reading a value - it is 0. These are both connected to ground somehow. Do you have a photo of both sides of the board?
I'm a refugee of the great dropbox purge of '17.
Project details (schematics, layouts, etc) are slowly being added here: http://samdump.wordpress.com


arma61

"it's a matter of objectives. If you don't know where you want to go, any direction is about as good as any other." R.G. Keen

R.G.

Where you suspect a short, turn off the power to the circuit, set your meter to read low resistance and test the resistance between the points. This lets you tell the difference between two points that are at the same voltage because they're shorted, and two points that are at the same voltage because they're open.

In this case, I'd also read the in-circuit resistance between collector and base. If R3 was open, then the base and emitter would both be pulled to ground by their respective resistors (and would show 100K between them, btw) but with no bias on the base, the transistor would be off and the collector would be pulled to 9V by the collector resistor.
R.G.

In response to the questions in the forum - PCB Layout for Musical Effects is available from The Book Patch. Search "PCB Layout" and it ought to appear.

wildebelor

Found the solder bridge just a little before Arma61 did!
Man do I feel dumb!!!
Way too tired - lesson learnt; don't do this when you're overworked!

Thanks everyone!
I can't think of anything funny just yet.

deadastronaut

https://www.youtube.com/user/100roberthenry
https://deadastronaut.wixsite.com/effects

chasm reverb/tremshifter/faze filter/abductor II delay/timestream reverb/dreamtime delay/skinwalker hi gain dist/black triangle OD/ nano drums/space patrol fuzz//

arma61

Great! another happy ending story!!!
"it's a matter of objectives. If you don't know where you want to go, any direction is about as good as any other." R.G. Keen