Sola - Wah  [schematic]

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

Hello,

Recently i have bought a colorsound wah. This one is a bit different from others, but there are lots of variations i see. I have seen pictures just like this one:
viewtopic.php?f=19&t=11121
The one i have is not completely working as it should. There is a lot of movement without wah-effect. While trying to find out what is wrong i made some pictures, and a layout. Then it was little work to create a pdf with a pcb. I haven't seen one here before:
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SolaWahLayout.pdf
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yamyfz
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Post by yamyfz »

And the pcb, mirrorred for printing:
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SolaWahPcb.pdf
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yamyfz
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Post by yamyfz »

Btw, it is the same one as the pictures posted by Dave Dabo, in topic mentioned above.
The tropical caps are probably 10n and 220n. The big white cap reads 0,15uF / 63V. Transistors are BC183A.

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yamyfz
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Post by yamyfz »

And here are some pictures:

Maybe a good time to introduce myself. My name is Mark, i'm from The Netherlands. I got interested in electronics and effects when i heard what a Deluxe Memory Man can do.
I have learned a lot from the internet, and forums like free stompboxes. I hope that these pictures and layout can be helpfull. Greetings,

Mark
Attachments
P1010066.JPG
P1010051.JPG
P1010056.JPG
P1010057.JPG
P1010060.JPG
P1010065.JPG
P1010067.JPG

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Manfred
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Post by Manfred »

What are the dimensions of the PCB-Board?

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yamyfz
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Post by yamyfz »

The pcb measures 80 x45mm. The pdf should be the right size.

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Deepfuzz69
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Post by Deepfuzz69 »

Kool pedal 8) too bad it wasn't the fuzz wah, but just as good :applause:

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Post by Deepfuzz69 »

Early or mid 70's? :hmmm:

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yamyfz
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Post by yamyfz »

Yeah, it's really a cool one. I was also wondering about the age. According to the other topic, it is probably a late 60's/ early 70's model. It's pretty much the same circuit as used in the wah/fuzz/swell. Except for one cap (the big white one), that is 150n instead of 220n. It is working at the moment, but the sweep seems way too short. I'm trying to find out if it is just the potmeter that causes this, or something else. (Or these 2 combined) Or maybe it's just supposed to be like this? I don't really know, It's the first one i have seen.
I dont know much about wah's. So i started reading at geofex. This one is close to the vox wah mentioned there. The voltages of the first transistor seem to be ok: 4,4V col/0,6V base/0V emit
The second q, im not sure about it: 8.78V c/ 2.36V b/2,62V e (Help is welcome) It should look more like 8,8/3,6/3,0V right?

I'm not sure about the values of the tropical fish caps either. Maybe that one of the smaller ones is iffy. That could be a cause for a small wah-sweep, if i'm correct. It just seems to miss a lot on the bass and treble side..
I've measured resistance between the potmeter lugs. It only wah's on a small portion of this. Tried different pots, different heights for the pot. And different potmeter ranges. No matter what, lin/log etc, there always is a lot of sweep without wah.. (you can see resistance changing between the potmeter lugs, but no wah effect for a big portion)

For the potmeter, I've read this one should be fine:
Bourns 91A1A-B28-E22L
I'm not sure, but i think that the 'E' in this number stands for E- taper. Which is a bit like C rev log.

One thing is sure: you can hear it has potential for a nice thick sound. :D

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Manfred
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Post by Manfred »

I suppose that this stand allone Wah has the same schematic as the Wah Board part of the SOLA SOUND WAH/FUZZ/SWELL.
solaSoundFuzzWah.jpg
I made a layout clone with SprintLayout 6.0 with the component values from the schematic above.
solaWah.zip
(10.44 KiB) Downloaded 111 times

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yamyfz
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Post by yamyfz »

That's right Manfred. I think everything is the same, except for the value of that big white cap. That one is 150n, 20%, 160V. On schematic, it's the one at the top (.22 next to a 100k resistor).

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