AMZ FX ANALOG ALCHEMY GEOFX MEF ROG MEF DIY WIKI

Tube Screamer no screaming!

Started by Cardboard Tube Samurai, February 11, 2007, 01:23:49 AM

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Cardboard Tube Samurai

February 11, 2007, 01:23:49 AM
 >:(

So this is the 2nd one I have built (from the GGG layout) but for some reason I am getting no sound out of it. I have checked all voltages and it seems that the problem is somewhere around Q1... I am getting E = 0, B = .01, C = 8.5. From my research they should be 0, 3 and 3.5 respectively. A couple of the voltages around the IC are about 0.1 to 0.5 lower than they should be, but I am guessing that is a result of the Q1 and surrounds issue. The only mod I have done is the asymmetric clipping diode as per http://www.generalguitargadgets.com/pdf/ggg_its8_mods.pdf

Anyone got any suggestions!?!? I am tearing my hair out here. I was supposed to have it finished for a guy LAST weekend!!!

Cardboard Tube Samurai

#1
February 11, 2007, 01:28:43 AM
I should add that I have gone over all of the solders again with the soldering iron just to make sure that they are all clean. In doing so I discovered a solder bridge between pins 7 and 8 on the IC which I have since rectified... do you think that could have caused issues?

R.G.

#3
February 11, 2007, 09:47:29 AM
read and comply with "What to do when it doesn't work"
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.

Cardboard Tube Samurai

#4
February 12, 2007, 04:01:09 AM


Pretty much the same as that only what I said above for values at Q1. What more do you want or need? Some of the values I have read are a bit lower but that's because my battery is at about 8.5

96ecss

#5
February 12, 2007, 07:27:09 AM
Hi,

I had a similar problem with my 808 from GGG. R.G. informed me that the readings for Q1 from the GGG site were incorrect. I was getting these readings at Q1:

C - 8.70
B - 3.33
E - 2.70

The Emitter should not be 0. Here is a link to my post with R.G.'s reply and all my readings.

http://www.diystompboxes.com/smfforum/index.php?topic=52858.0

It turned out the I had soldered 1 lug of C10 in the wrong place. The incorrect voltage specs on GGG threw me off. Once R.G. set me straight, I tested with an audio probe and found the problem within minutes. I'm not saying you made the same mistake as me, but it's worth checking with the audio probe. 

I hope this helps.

Dave
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