SolaSound - Tonebender 1971  [schematic]

Discussion regarding early stompbox technology: 1960-1975 Please keep discussion focused and contribute what info you have...
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Fender3D
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Post by Fender3D »

This arrived for repairing.

It's a late '60 Tone Bender by Sola Sound.
I redraw the schematic with actual values and wires color... :thumbsup

Fuzz control works reversed.
Transistors and diode are unsigned.

Enjoy
The attachment SolaSoundTB1sm.JPG is no longer available
SolaSoundTB1sm.JPG
SolaSoundTB2sm.JPG
SolaSoundTB3sm.JPG
SolaSoundTB4sm.JPG
SolaSoundTB5sm.JPG
Schematic
SolaSoundTB6sm.JPG

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sinner
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Post by sinner »

cool bro, thanks for sharing

what's the actual board dimensions?

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Fender3D
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Post by Fender3D »

76.9 X 75.9 mm

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armdnrdy1
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Post by armdnrdy1 »

Why couldn't you have received a Colorsound flanger for repair? :slap:

I'm working on the board routing and....I could use a few trace side shots!

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Post by Fender3D »

more pics...
P6170005.JPG
P6170006.JPG

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kymar
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Post by kymar »

Thanks for nice pic!
Could you measure voltages Qc1, Qc2, Qc3, please?

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sinner
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Post by sinner »

kymar wrote:Thanks for nice pic!
Could you measure voltages Qc1, Qc2, Qc3, please?
this!

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Electric Warrior
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Post by Electric Warrior »

Can you read the pot codes? Probably early '72.

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Post by Fender3D »

kymar wrote:Thanks for nice pic!
Could you measure voltages Qc1, Qc2, Qc3, please?
Q1:

C = -5.024 V
B = -1.300 V
E = -1.232 V

Q2:

C = -5.024 V
B = -1.232 V
E = -1.140 V

Q3:

C = -2.540 V
B = -0.071 V
E = 0 V
Electric Warrior wrote:Can you read the pot codes? Probably early '72.
On pot you find:

Radiohm 100K A D-74

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Fender3D
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Post by Fender3D »

I forgot

Battery = 9.70V

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Post by Fender3D »

Updated schematic:
added transistors voltages, moved battery switch to output jack
Sola Sound Tone Bender.pdf

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Electric Warrior
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Post by Electric Warrior »

Fender3D wrote:
On pot you find:

Radiohm 100K A D-74
Thank you! That would be D-71. By 1974 the pot codes were stamped into the top surface of the pots.

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Post by Fender3D »

lol

1.2 corrected electros polarity
Sola Sound Tone Bender.pdf
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Post by jalmonsalmon »

32uF is a funky value but I assume since it is just going from -VCC to ground, a 33uF will be okay or whatever works LOL

thanks!

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Electric Warrior
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Post by Electric Warrior »

Sure. Sola Sound mostly used 22µF or 25µF as a power filter cap for these in that particular era. They started out with 50µF, but whatever works..

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Post by Bret608 »

Cool unit! Glad you were able to share the voltages. Q3 was definitely what I would have expected. Q1 and Q2 are slightly higher than I thought they would be on the collector. Then again it's still roughly half supply voltage.

I know these "top hat"-style transistors are normally not marked. Has anyone ever seen marked versions of them anywhere?

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Electric Warrior
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Post by Electric Warrior »

I've seen a couple of marked ones in Tone Benders, but never the same type twice. :mrgreen:

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Post by Bret608 »

That's what I love about this circuit, nice and forgiving of different transistor types.

EW, I'm actually working on a build right now using your MkIII layout. The one with the 680k/150k bias string...I think I've got just the right gains/leakages in my stash of no-name germaniums. We'll see I guess!

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Post by Electric Warrior »

Good luck! Trying different types in this circuit sure pays off! Q3 is quite sensitive to leakage. Great for shaping the tone. And I found that transistors wired up as a diode sound different from the germanium diodes I have. Worth a try!

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Post by sinner »

I don't think leakage is that bad in mk3. I kind of like it if it leaks. I often fake leakage setting resistor or resistor in series with pot between C and B

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