GGG Shin ei companion fuzz has no fuzz?

Started by HeadCase, July 07, 2014, 11:45:51 PM

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HeadCase

Hey everyone, I'm new here and getting started building pedals. I have put together a GGG companion fuzz with an added mid scoop pot, and it has some issues.
Here is the project page I'm working from, it has the schematic, list of materials, layout and such: http://www.generalguitargadgets.com/effects-projects/fuzz-tones/shin-ei-companion-fuzz/
-The pedal bypasses fine, when I turn it on it changes the sound (slightly darker), but there is no fuzz or gain at all. The volume pot works, the scoop pot appears to work and the fuzz pot changes the sound a little but not much (normal for these fuzzes).
-I have used the parts that came with the kit, and have double checked that they are in the correct place. For the mid scoop, I used a 5K pot between the 0.1uf cap and ground.

There seems to be issues with the transistor voltages, but I do not know why or how to fix them. Below is formatted as-  what the voltage is(what it should be)

Q1
C =6.6(6.6)
B =0.62(0.6)
E =0(0)

Q2
C=9.09(2)    (obviously these are very high?)
B=8.12(.6)
E=0(0)

Q3
C=5.96(6.6)
B=0.7(0.7)
E=0.1(0.1)

I tried switching Q1 and Q2 (since they are the same), then I got very high voltages on Q1's C (around 9) and B (around 7.5) and correct voltages for Q2, which makes me think that there could be a problem with that transistor, but I would think the problem would more likely be my fault than a part.

Thanks so much for helping me out, I'm really excited to get this thing going!

PRR

Did you get PCB and parts from GGG, or totally DIY (aside from documentation)?

> B=8.12(.6)

This *could* be a backward transistor: E and C reversed.

Q1 and Q2 can be *any* _NPN_ part. If you have any 2N3904, try them.
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HeadCase

PCB and parts from GGG, With the exception of the 5K pot. I'll try moving the transistor and see if that helps, thanks.
I wish I had some other transistors to try, but I don't unfortunately.

HeadCase

I would want to switch both transistors, correct? Or just the one?


bluebunny

Quote from: HeadCase on July 08, 2014, 01:31:06 AM
I would want to switch both transistors, correct? Or just the one?

I think Paul is suggesting to check the pinout of Q2.  It also looks to me like your Q3 is back to front (or my failing eyesight is deceiving me) - the flat on the silkscreen should match the flat on the transistor.  And welcome!
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Ohm's Law - much like Coles Law, but with less cabbage...

LucifersTrip

Q1 & Q2 look correct. The tabs (E) are facing down, towards the outside of the board, which is ground.

Try swapping transistors. If you get the same voltages, there's most likely an error in the soldering or wrong/bad component.
If you get bad voltages on Q1, then it's prob a dead transistor.
always think outside the box

HeadCase

I don't have any others to try, I'd have to get some, but when I swapped the two with each other, I got high voltages on the new Q1, which makes me think it's that transistor. Did that make sense?

HeadCase

Quote from: bluebunny on July 08, 2014, 03:03:44 AM
Quote from: HeadCase on July 08, 2014, 01:31:06 AM
I would want to switch both transistors, correct? Or just the one?

I think Paul is suggesting to check the pinout of Q2.  It also looks to me like your Q3 is back to front (or my failing eyesight is deceiving me) - the flat on the silkscreen should match the flat on the transistor.  And welcome!
Q3 is lined up correctly, it's just in a shadow. Thank you!

LucifersTrip

Quote from: HeadCase on July 08, 2014, 11:24:33 AM
I don't have any others to try, I'd have to get some, but when I swapped the two with each other, I got high voltages on the new Q1, which makes me think it's that transistor. Did that make sense?

Yes...if those transistors were the same and both working well with good gains, you should've gotten the same voltages as you first reported.

Try swapping each for Q3 and test voltages....see if you get a similar failure.

If you have a Shack near you, this is a quick way to go:
http://www.radioshack.com/product/index.jsp?productId=2062586

always think outside the box

HeadCase

Alright, I'll try that. I contacted GGG this morning and theres a new one in the mail, great customer service. But I might hop over to radio shack later, thanks for the link.

bluebunny

#11
Quote from: HeadCase on July 08, 2014, 11:25:39 AM
Q3 is lined up correctly, it's just in a shadow. Thank you!

Cool.   8)   The shadow was indeed deceiving my old eyes!
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Ohm's Law - much like Coles Law, but with less cabbage...

HeadCase

It's alive! I got a new transistor from GGG and everything is as fuzzy as it should be. They have awesome customer service, got me a new transistor in 24 hours.   Thanks for the help diagnosing the issue everyone.

HeadCase


My hand-painted snoopy/woodstock graphic (companions, get it? 8) )

LucifersTrip

The voltages told all...

Woodstock's too cute for that :icon_evil:  ;)


always think outside the box

HeadCase

Haha, they are a little too cute and polite for such a nasty fuzz, but I couldn't resist!  ;D

bluebunny

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Ohm's Law - much like Coles Law, but with less cabbage...

duck_arse

Quote from: HeadCase on July 10, 2014, 09:14:20 PM
My hand-painted snoopy/woodstock graphic (companions, get it? 8) )

"||| | ||| |||| || ||||| | | |||| | !"
You hold the small basket while I strain the gnat.

bluebunny

#18
Quote from: duck_arse on July 11, 2014, 09:37:21 AM
"||| | ||| |||| || ||||| | | |||| | !"

I was gonna say the same thing...   ;)

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Ohm's Law - much like Coles Law, but with less cabbage...

HeadCase

Thanks guys. I love the Woodstock talking, that might be my next pedal ;)