Help with GGG's Scrambler...i think i will become insane!

[gigimarga]

Hello,

I've built an Ampeg Scrambler using the GGG's layout (some time ago i'd built one using Tonepad's layout, but it never works...my fault I think).

Because here it's impossible to find 2N5306 i used some MPSA13 (in Tonepad's i used BC517 with no luck), instead of BC169B i used a 2N3904 and all 5 diodes were 1N4148 (as i saw here: http://www.generalguitargadgets.com/diagrams/scrambler_sc.gif).

But...no luck at all...it sounds very clear with my Squier Affinity with the Blend pot at minimum...with the the Blend at maximum i hear no sound and after i move it a little i hear a clear signal too!!!

I boosted it using an original Boss Blues Driver BD-2 (which has a lot of volume) and i hear the Boss very clear 

Are these 2N5306 so important??? Nothing can substitute them?!!

Using a 9.12V battery i have the next voltages, which seems to be OK as i saw in another topics:

Q1: C = 9.12     B = 4.33     E = 3.44

Q2: C = 3.53     B = 0.90     E = 0.24

Q3: C = 9.12     B = 4.50     E = 3.50

Q4: C = 8.77     B = 4.50     E = 3.50

Thx a lot all again!

[Mark Hammer]

My datasheets show the pinout for the 2N5306 as being ECB, and the MPSA13 as EBC.  Maybe that is where your problem lies.

Only three little pins, yet so many problems!

[gigimarga]

Thx again Mark for your answer...this is the layout that i used: http://www.generalguitargadgets.com/diagrams/scrambler_lo.gif...as you can see the pinout of the transistors is E-B-C, so who will use 2N5306 will must to wriggle them 

[Mark Hammer]

The 2N5306 pinout I mentioned was for a Fairchild unit.  I do not know if the same pinout applies to all 2N5306 transistors in production currently or in past.

Whenever you make a circuit that uses discrete transistors, it is alwasy a good idea to keep the datasheets handy, and to check the pinouts of the transistors when you get no sound or get something unexpected.

[gigimarga]

I used MPSA13, not 2N5306...i relook at the schematic and they are positioned right 

[Mark Hammer]

Okay, that is one thing you do NOT have to worry about.

[gigimarga]

Thx...but what to do ?

[gigimarga]

Look here: http://ustomp.com/?p=9...almost the same voltages 

[tiges_ tendres]

Is your input getting shorted to your output somehow?

[slacker]

Make an audio probe and see where the signal disapears.