MXR - Doubleshot Distortion

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.
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oscarv77
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Post by oscarv77 »

I know this is a really old topic, but I finally got my hands on a broken one and I was able to get the pcb out of the enclosure. The one I have has a burnt out resistor or 2 (wrong adapter plugged in). Since it's out of the box, I'm willing to take high-res pictures of both sides (double-sided PCB with 99.5% SMD components) if the interest is still there. In my searching for the schematic, it seems that it's one of the pedals that has proved to be elusive.

Let me know; I'll have the pedal out of the box and ready for pictures until I can get a reply from Dunlop on what to replace to fix it.

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Post by Ice-9 »

Yes, take some pictures of the component side please. There is always interest. :applause:
It's fairly straight forward, if you want to start it , press start. You can work out the rest of the controls for yourself !

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relic_elite
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Post by relic_elite »

i think i have one of these lying around
i will try to extract the pcb this week and take some shot ;)

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jcgss77
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Post by jcgss77 »

Sorry for necrobumping, but has anyone gotten those pics that were promised, or possibly has the schematic been traced? Thank you!

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theehman
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Post by theehman »

Anybody still interested in this? I have one here that's not working and already dismantled.
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Post by okgb »

No one would mind if you posted pix, see if that re-stimulates interest thanks!

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Post by theehman »

okgb wrote:No one would mind if you posted pix, see if that re-stimulates interest thanks!


I'll see if I can get some pictures up this weekend.
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hemisfeer
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Post by hemisfeer »

Hey everyone, I have a double shot distortion I'm trying to fix. The problem is with the focus control for the top channel. With the focus out, (led off) I get manipulation of the midrange, however, with the focus in, (led on) I get no midrange control. I changed U16, but it didn't fix the problem. I'm guessing, the switch routes the midrange signal to a different part of the PCB, but it's not getting to wherever it needs to go. Any direction would be greatly appreciated.

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Post by FuzzMonkey »

hemisfeer wrote: 11 Jan 2021, 00:51 Hey everyone, I have a double shot distortion I'm trying to fix. The problem is with the focus control for the top channel. With the focus out, (led off) I get manipulation of the midrange, however, with the focus in, (led on) I get no midrange control. I changed U16, but it didn't fix the problem. I'm guessing, the switch routes the midrange signal to a different part of the PCB, but it's not getting to wherever it needs to go. Any direction would be greatly appreciated.
Does the bottom channel work? Is it possible to trace the path of the focus control from the bottom channel?

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hemisfeer
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Post by hemisfeer »

Hey FuzzMonkey,

Its a pretty busy circuit. I'm not sure if they're "symmetrical", but, yes the bottom channel does work. Somewhere the signal is getting shunted to ground before it gets to the mids pot after the switch. Its just trying to figure out where its going.

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hemisfeer
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Post by hemisfeer »

Hey everyone, there has been a development in the MXR doubleshot issue. I bought a second one recently from a person on ebay who tested it and sold it as completely functional. I get it and it has the same issue where the mids control on the top channel is non functional with the focus button depressed. Does anyone else out there have a doubleshot distortion that acts this way? The odds that these two pedals have the exact same malfunction are slim at best. I'm starting to think that's how they were supposed to work.

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hemisfeer
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Post by hemisfeer »

Good news on the doubleshot distortion. I got confirmation from a seller on eBay that the mids control on the top channel does not work when the focus control is depressed. The bottom channel's mids control works with the focus button in or out. Weird set up.

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