Jext Telez - White Pedal  [traced]

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Jext Telez - White Pedal

Postby Motter » 04 Jan 2018, 03:26

I decided to take some photos before I sell this one off. It's a cool pedal, but way too huge and expensive to keep on the pedalboard. I planned to do a full trace, but based on the switching, the inductor, transistor count/types, and the pot values, I'm confident enough this is simply a Vox transistor distortion and mid-range boost circuit straight out of the solid state amps of the 60s, with maybe some slight tweaking.

Transistors Q1-Q4 are BC548 and QD1-QD3 are 2N4125

The "YOKO" switch changes between three different caps in series with the inductor, the two I can read are 473 and 104.

The inductor had no markings, so I'm guessing it's custom made it vintage unobtainium. There's no reason to think it isn't what's listed on the Vox schem though.

Volume pot is B25k, Gain is C5k, Treble is B1k, and Bass is A10k

Photos are here: https://m.imgur.com/a/SsiID

The Vox schem: http://www.davidmorrin.com/_/rsrc/14279 ... 6%20PM.png

http://www.voxsupreme.org.uk/images/eff ... mrb_02.jpg
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Re: Jext Telez White Pedal

Postby Motter » 04 Jan 2018, 16:18

Wow a lot of those photos are pretty lousy. I still have it disassembled today if anybody wants any specific photos/measurements.
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Re: Jext Telez White Pedal

Postby Motter » 04 Jan 2018, 23:47

I actually did the trace myself today, and it's definitely just the Vox circuit. It seems to use the distortion stage from the first circuit I posted, and the midrange boost from the second. I'll see if I can come up with a unified diagram for yall....
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Re: Jext Telez White Pedal  [traced]

Postby Motter » 05 Jan 2018, 00:53

Here's the schematic. Cap Values TBD, they're hard to read.

Image

I've drawn the inductor as two, like Vox did, but it might just be a single inductor. I don't know much about inductors.

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Re: Jext Telez White Pedal

Postby modman » 05 Jan 2018, 13:26

In the Vox schematic, there are two 250mH coils in series... but in the pedal at hand, it just seems a wah inductor... which are about 500mH if I'm not mistaken...

Motter wrote:The "YOKO" switch changes between three different caps in series with the inductor, the two I can read are 473 and 104.


mrb_02.jpg


C14 = 0.22 µF
C15 = 0.1 µF
C16= 0.047 µF


Don't hesistate to attach images of undocumented pedals. But try to keep the size manageable.
Use daylight and turn on the macro function of your camera :thumbsup


Link
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Re: Jext Telez - White Pedal

Postby Motter » 05 Jan 2018, 15:13

You are correct on all counts. I've gone back with a magnifying glass to read all the caps, and I will attach an updated schematic later today.

Is there any way to measure the inductor?
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Re: Jext Telez - White Pedal

Postby Motter » 05 Jan 2018, 17:07

Image

Here is the final schematic with capacitor values. The only cap I'm not 100% sure about is the 300n in parallel with the clipping diodes (QD1 and QD2). I cannot see any markings on this one, but my multimeter which measure capacitance says it is 300n.
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