madbeanpedals::forum

Projects => Tech Help - Projects Page => Topic started by: murdog47 on July 16, 2013, 10:09:32 PM

Title: Green bean to SRV special trouble
Post by: murdog47 on July 16, 2013, 10:09:32 PM
So I used a green bean board to plug in the specs from the SRV special. It pushes a faint signal (very quiet signal, I have to crank the amp to 9 really hear anything and it still isn't much) that sounds terribly compressed. When I adjust the pots I get all kinds of old school Atari noises. Traced through it a couple times and it looks good but something is wrong. Here are my voltages. I'll get pictures up as soon as I can.

IC - JRC4558D
1. 8.49
2. 8.51
3. 8.45
4. 0.00
5. 8.45
6. 8.49
7. 8.46
8. 9.14

Q1

8.46, 8.45, 9.15

Q2

8.43, 8.43, 9.15

Fishy eh?

Also to keep with the SRV Special Schematic I did the following

C2 jumper
R5 omit
C3 omit
C8 jumper
C9 jumper
R15 jumper

along with the value changes that applied
here is the schem I used

http://www.aronnelson.com/gallery/main.php/v/ulysses/ulysses_layouts/ulysses_ts_srv_special/matsumin_ts_srv_special_schem.gif.html?g2_imageViewsIndex=1
Title: Re: Green bean to SRV special trouble
Post by: RobA on July 18, 2013, 12:00:41 AM
Which transistors did you use? Could it be the pinouts? The voltages look kinda like an ECB in an EBC position.
Title: Re: Green bean to SRV special trouble
Post by: murdog47 on July 18, 2013, 02:16:56 AM
I can't believe I failed to check the transistors. If there was a smiley hitting his head against a wall I would insert that here ___. Thanks for assisting in removing my head from a place it did not belong  :D
Title: Re: Green bean to SRV special trouble
Post by: RobA on July 18, 2013, 03:02:50 AM
It's good that it's an easy fix. I wouldn't feel too bad about the transistor orientation either. Just a bit ago, I blew up, literally, two LM337's because I was convinced I had the pinouts right. It was only after the second one blew shrapnel all over the living room that I figured I should re-read the spec sheet a bit more carefully.
Title: Re: Green bean to SRV special trouble
Post by: jimilee on July 18, 2013, 03:19:52 AM
Quote from: RobA on July 18, 2013, 03:02:50 AM
It's good that it's an easy fix. I wouldn't feel too bad about the transistor orientation either. Just a bit ago, I blew up, literally, two LM337's because I was convinced I had the pinouts right. It was only after the second one blew shrapnel all over the living room that I figured I should re-read the spec sheet a bit more carefully.
nice!