Darkglass - Vintage Microtubes  [schematic]

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.

Re: Darkglass - Vintage Microtubes

Postby dgrippin » 24 May 2018, 15:53

Hello. New member here.
Been researching these pedals for a long time looking for a good clone. Recently built the Guma Antique. I'm having some strange issues I'm unable to suss out. I'm getting only clean signal with pedal on. The pots don't do anything to change the sound. And once the blend is up about 90 precent or higher, all signal is lost. I have access to a lab with O-Scopes and large fluke multimeters like the 3458 to diagnose the ICs, just not sure how to go about it. Any help with signal flow or the order i should check components in to find out where the signal is stopping? I'm really stuck here.
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Re: Darkglass - Vintage Microtubes

Postby dgrippin » 25 May 2018, 18:53

Got it figured. I have shorts to ground at level pin 3, TL074 pins 8 and 9. I just can't find where the short is
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Re: Darkglass - Vintage Microtubes

Postby mindyou » 24 Mar 2019, 00:30

Just wanted to share that I built the pedal using Baja's pcb and it came alive on the first try.
That was amazing, thanks Steve!
dg-vmt-bringup.png
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Re: Darkglass - Vintage Microtubes

Postby mindyou » 24 Mar 2019, 00:32

This is the final pedal:
dg-vmt-case.png

Don't mind the tie-wrap. That is because it is sitting on a holeyboard.
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Re: Darkglass - Vintage Microtubes

Postby skizoide » 28 Mar 2019, 20:13

Hi. After all sorry for my english.
I made this circuit, using the last verified schematic, and etching my own layout. I made it two times, and both of them, have the same "problem". I hear a "white noise" (or something similar) after I play some notes, when I stop playing. It last 20-25 seconds, and then fade out, and silence. And if I play again, after it, again this noise. It's something that happens when the pedal detects sound, but it stops as though something is discharging. I tried with 3 different power supplies, with the same result. Any clue to solve this strange problem?
Thx.
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Re: Darkglass - Vintage Microtubes

Postby skizoide » 28 Mar 2019, 20:29

This is the layout I used.

And in this link, there's a video with the problem (the noise fading in minute 0:52 and ending)
https://www.dropbox.com/s/9vndb07uqsraf ... 0.mp4?dl=0

Thx
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