tube screamer...nothing!

[gtangas]

Hi guys

Need some help

I finished the MB open source tube screamer but it don't work! No sound.. dead quiet.

Check for bridges, reflow some points, etc

these are the readings for the IC

1: 7.30
2: 7.30
3: 7.50
4: 7.50
5: 7.50
6: 5.92
7: 7.5
8: 7.66

on the transistors i have 7..... v on the three poles of each one

The battery its not new and is reading below the 8v (+/-7,5)

some pics



[img]http://i775.photobucket.com/albums/yy38/gtangas/20130306_223719_zps751b3980.jpg[/img

any tips?

[jkokura]

I'd bet you have a solder bridge somewhere.

You should be reading ~9V on pin 8, 0V on pin 4, and ~4.5V on pins 1-3/5-7. Because you have full voltage on your ground, I would start looking for a bridge on your ground plane. Also, your voltage divider isn't working, so possibly there are multiple errors.

Keep at er! This is solveable.

Jacob

[hammerheadmusicman]

I can't see a high res solder side pic, maybe it's not coming up, or i'm being an idiot, but if not that'd be helpful

[gtangas]

look again for some bridges and i cant find none. baaaaa!!!

here is a pic of the tracks side



where is the voltage divider?

[gtangas]

and another pic of the spdt wiring. for the comp switch i´m using a on/on ass well

[jkokura]

Take your voltages again. If you're still getting 7.3V on your ground plane, there is definately a broken part or a bridge.

jacob

[jimilee]

I guess we'd have to see the layout it came from to see what is ok to be bridged and what's not ok.

[gtangas]

Take your voltages again. If you're still getting 7.3V on your ground plane, there is definately a broken part or a bridge.

jacob

II think it's the trans.. I didn't find the 2n5088 that Brian tells on the boom and use the 2sc1815

I was checking the pins and the 2n5088 is cbe and the one I use is ecb... I think that explains why I have positive volt on the 4pin of the op amp

[gtangas]

solved and working!

Noob issue! The problem was the trans.

I followed the schematic from Brian and on the mods info he wrote that he change the sc1815 to the 2n5088. so wen i went "shopping" i didn't find the 2N so i bought the sc... I never assume that this one ad a complete different pinout! 

Today i bought a few bc238 that is an equivalent to the 2N...the pinout is the opposite (EBC vs CBE) but i reverse the position on the board and voila!!

I omit the bright switch.... to arsh for my ears!!

The comp switch is ok, but i cant see any light from the 3mm leds!