Author Topic: Please help me out - debugging my Ruby Bassman amp  (Read 7702 times)

Rutger

Please help me out - debugging my Ruby Bassman amp
« on: May 03, 2010, 08:58:02 AM »
Hi,

This is my very first build, a Ruby Bassman amp from runoffgroove.com http://runoffgroove.com/ruby.html.
Well, stubborn as I am, I gave it a view extra’s:

- 2k gainpot instead of the 2k resistor
- tonepot like the one on the Noisy Cricket
- mastervolume right before the headphone/speaker jack

So far, no sound/noise or whatsoever comes out of the amp. I checked and double checked my schematic, layout and perfboard artwork but I can’t find anything, so I hope you can help me out.

I did some measurements on the JFET and the IC. The measurements are done with the tonepot disconnected.

JFET
D= 9,2V
S= 8,4V
G= 8,4V

IC
P1= 2,9V (gain on 10)
P2= 0,4V
P3= 0V
P4= 0V
P5= 0,7V
P6= 9,2V
P7= 0,4V
P8= 4,6V (gain on 10)

The only thing I can tell from these measurements is that things go wrong, but I don’t have any clou…
« Last Edit: May 03, 2010, 09:06:10 AM by Rutger »

Rutger

Re: Please help me out - debugging my Ruby Bassman amp
« Reply #1 on: May 05, 2010, 04:29:37 AM »
Anyone who can help me out, please?

Load3r

Re: Please help me out - debugging my Ruby Bassman amp
« Reply #2 on: May 05, 2010, 10:16:11 PM »
You might want to post this in a different part of the forum.
There isn't much activity in this part, and your project doesn't have much in common with OD250.
I would help you myself if I had the know how, but I'm sure someone else would be willing seeing as you have posted up your voltages.
My only advice would be to check for cold solder joints or solder bridges. The output might be accidentally grounded?
Good luck!

Quackzed

Re: Please help me out - debugging my Ruby Bassman amp
« Reply #3 on: May 05, 2010, 10:23:26 PM »
it looks like the s and g of the jfet should be a diode drop apart. (i think) so, i'd look at the 1m5 resistor and see if its shorting or something, double check its value, check transistor pinout as some jfets  are different pins for d g s...
nothing says forever like a solid block of liquid nails!!!

Rutger

Re: Please help me out - debugging my Ruby Bassman amp
« Reply #4 on: May 08, 2010, 06:05:05 AM »
I'm sorry, I thought this forum part was for IC based stompboxes in general.

I checked all the partvalues and solderjoints for I thought of a shorting as well, but they're fine. I figured out that the JFET is broke... so I need to get a new one.

So that's one problem solved, now there's still something wrong at P5 of the IC, the voltage should be 4,5V but i can't figure out what couses the problem...?



FisTheGoon

Re: Please help me out - debugging my Ruby Bassman amp
« Reply #5 on: May 08, 2010, 07:23:18 AM »
You might want to post this in a different part of the forum.
There isn't much activity in this part, and your project doesn't have much in common with OD250.
I would help you myself if I had the know how, but I'm sure someone else would be willing seeing as you have posted up your voltages.
My only advice would be to check for cold solder joints or solder bridges. The output might be accidentally grounded?
Good luck!

What Load3r mean is to post your problem in Building your own stompbox area as there are more people to answer or read the problem.Thanks ;D

Load3r

Re: Please help me out - debugging my Ruby Bassman amp
« Reply #6 on: May 08, 2010, 02:21:36 PM »
Thank you Fis. I like how you worded that better.

Rutger

Re: Please help me out - debugging my Ruby Bassman amp
« Reply #7 on: May 09, 2010, 04:08:58 AM »
Thanks, I'll try it there!