tonebender 3-knob cap ?

[analogguru]

Today I found a picture of a colorsound tonebender 3-knob which made me think:



Compared to the picture at Fuzzcentral and another one I found on ebay, it is obvious that there is used a yellow film-capacitor capacitor instead of the "2n2" ceramic-disc in the tone-cotrol section.

The size would let me assume a 22n/400V
The ceramic disc is also huge and could be a 22n/500V....from thickness.
The PCB-tracks are also prepared for such a big capacitor.

making a circuit simulation with the 22n gives a bass-roll off starting at 1kHz and a cut of 20db at 100Hz...what would make sense....

this lets me assume, that ALL schematics are wrong....

Has somebody access to an original 3-knob, that this could be verified ?

analogguru

[phillip]

Here's Stuart Castledine's 3-knob ToneBender page that shows his correct schematic...he's most likely had several of them:

http://homepage.ntlworld.com/s.castledine/greenfuz/solasound.html

I also have a very nice 500KB picture of a 3-Knob Park Fuzz Sound circuit board (the same board as in the Sola Sound) that has a clearly marked .0022uF, 500V capacitor on lug 1 of the Tone pot.  There are some differences in the Park Fuzz Sound 3-knob circuit, but the tone controls between it and the Sola Sound are the same.

All the copies of the Sola Sound 3-knob ToneBender have a 2200pF (0.0022uF) capacitor there except for the Vox MKIII, which has a 2000pF.  The 3-Knob ToneBender page at Fuzz Central has several schematics of different versions of the circuit.

Phillip  

[Prive]

All the copies of the Sola Sound 3-knob ToneBender have a 2200pF (0.022uF) capacitor there except for the Vox MKIII, which has a 2000pF.  The 3-Knob ToneBender page at Fuzz Central has several schematics of different versions of the circuit.

Phillip  

2200pf is .0022
.022 is 22nf

Where is the mistake?

Saludos, Marcelo.

[phillip]

Whoops!  I had a typing error there.  The 3-knob TB has a 2200pF (.0022uF) capacitor in the tone control section.

Previous post is also now corrected.

Phillip

[analogguru]

Maybe yes.....but this yellow capacitor seems to me bigger than 2n2..even for that time, 15mm long with a diameter of 8 mm....and the holes in the pcb are 22 mm apart....even on the original pcb...there are 2 holes with copper eyes, one is 15mm and the other one 22mm apart....

and one 0 too much happens somtimes even the experienced one..

when the ceramic disc is only 2n2 it must be a 2kV or 5kV type for its size...it makes me only think...and even a 22n would make sense there for the tone control as described above....

@Phillip
maybe you can look on the 500k file what is exactly written on the ceramic disc cap ?

analogguru

[Stuart]

No, it's definitely 2200pF  



BTW, if you've only seen pictures, how can you be so confident of the dimensions?  The cap is nowhere near 8mm diameter...

[phillip]

Dunno what's written on the ceramic capacitor in the picture on the website...that picture is the circuit board of a real Sola Sound 3-knob TB.  The 500KB picture that I have is of the circuit board in a Park Fuzz Sound 3-knob (the same thing as the Sola Sound 3-knob with a couple of different resistor values) and it has one of the axial-leaded capacitors in the tone control section with .0022uF, 500V printed on it.  It's a light blue capacitor with yellow printing.  The other capacitor in the tone control section is a 0.1uF tropical fish.

The only one of the Sola Sound 3-knob copies that uses a different capacitor in that spot is the Vox MKIII, which uses a 2000pF.

Phillip

[analogguru]

Many thanks for the help !
Now I can sleep much better....

BTW, if you've only seen pictures, how can you be so confident of the dimensions? The cap is nowhere near 8mm diameter...

The diameter was only an assumtion, but the length is possible to compare withe the 100n Siemens-cap (10mm) or "tropical fish" mullard-cap (10mm) and the track picture.

The size of the yellow cap surprises me for this time and voltage of 125V (must be some cheap "junk")

Surprising also the green "japanese" 100n on Stuarts picture...
It seems they used everything they could get...

Maybe for this reason the transistors are unmarked...
In the 70´s it was possible to buy unmarked transistors which were original but didn´t fulfill the specs 100% (leakage)....especially I know this about BC 107 - 109s and BFY90 from Telefunken.

Many thanks again,

analogguru