Schaller - Yoy Yoy Wha Wha  [schematic]

Discussion regarding early stompbox technology: 1960-1975 Please keep discussion focused and contribute what info you have...
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modman
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Post by modman »

analogguru on August 27 2007 wrote:There exists a schematic from a later version (the wha-wha-yoy-yoy) with plastic transistors. I am not sure if this schema doesn´t contain some errors.

I have some guts from the unit shown, but not from the solder side.
So if your friend could take a photo of the solder-side the schematic could be verified and maybe adapted to the unit of your friend....
I checked the Yoy Yoy Wha Wha I had lying around, and it is true, the schematic hosted floating around does contain some errors with regard to the unit I have here. After completing the check, I find it matches this schematic by diyguitarist:

http://www.diyguitarist.com/Schematics/BowWowYoyYoy.gif

Except for the transistors which are BC237
the 22nF are 27nF
the 250nF is 220nF
resistor on first transistor's collector is 15k instead of 10k
100 ohm on the 9V
100uF to ground

Was is not often noted, is that there is no bypass. Rather, the pedal switches between Yoy/Wha mode and Volume pedal mode. But some incredible tone sucking going on. I replaced all electolytes in this pedal, might pass to changing to better capacitors. With such a crappy plastic case, you ask yourself why bother.

Tightening the wah pot and setting it up right already made it a decent wah. Don't know about the the Yoy though and a some of bass distortion in the heel position.
Attachments
Tracing picture of the Schaller Yoy Yoy Wha Wha
Tracing picture of the Schaller Yoy Yoy Wha Wha
schalleryoywhadef.jpg (66.44 KiB) Viewed 2368 times
Schaller Yoy Yoy Wha Wha
Schaller Yoy Yoy Wha Wha
shalleryoywha.jpg (46.97 KiB) Viewed 2362 times
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Paul Marossy
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Post by Paul Marossy »

For the record, this is the correct schematic (ignoring the bypass switching). It has been verified with an original unit.
http://www.diyguitarist.com/Schematics/BowWowYoyYoy.gif
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BowWowYoyYoy.gif
_/\_/\_PJM_/\_/\_

http://www.diyguitarist.net

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sinner
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Post by sinner »

Hi Paul, any futher info about inductors? coil dimention, resistance?

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Mich P
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Post by Mich P »

Hi Sinner,
I've got a couple from an original i bought
early 90's (Plastic case).
The coil on both is 14mm
Dc resitance : 20,4 Ohms (red mark on this one)
117,2 Ohms on the second.
Mich P.

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Mich P
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Post by Mich P »

Hi Sinner,
I've got a couple from an original i bought
early 90's (Plastic case).
The coil on both is 14mm diameter
Dc resitance : 20,4 Ohms (red mark on this one)
117,2 Ohms on the second.
Mich P.

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sinner
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Post by sinner »

Thanks a lot Michu

Any info about the metal issue?

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Bernardduur
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Post by Bernardduur »

Got a couple of these ones in; great pedals that sound so different then the normal wah pedal

I added a six way switch to switch caps and make the wah stand out more (next to true bypass and raising the input impedance as they loaded down my guitar)
DSCF5326.jpg
'No more....... loud music.......'
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