MXR Distortion+ PCB Trace

[Steve Mavronis]

Here's a PCB trace for a MXR Distortion+ that I traced from my fried 1980 pedal, as viewed from the component side. I want to get this etched for myself so I can replace the damaged one to repair it. I'm still working on smoothing out the curved traces but I tried to get it as close a possible. If anyone wants it to repair theirs (or to make a clone) I will post a link to a better PDF 300dpi version later. Mine is the first pre-LED block logo model but this base PCB trace pattern is the same for the script logo model too.



Since I'm replacing the PCB with a non-original PCB and components anyway, do you think it wouldn't hurt to add a LED and DC Jack?

Here's what my broken MXR Distortion+ looks like now:

[mattthegamer463]

Of course not.  A DC jack isn't hard to hook up with the switching to dis-engage the battery, and if you convert to true-bypass and use a 3PDT you can have the LED virtually separate from the rest of the circuit.

[Steve Mavronis]

Yeah, I guess the vintage-ness of it no longer matters (since it's fried) if I drill holes into the MXR box to mod it.  I know how to do that by repeating what I did with my other clone build.

[Govmnt_Lacky]

Steve... a little off topic however, quite convenient.

Do you notice the difference between your Dist+ enclosure and other Hamond/NSC-type enclosures? The weight and size proportions? I posted another thread wondering where these can be purchased which you posted in.

Did they use a sturdier metal? Different spec of Aluminum perhaps?

[Steve Mavronis]

Do you notice the difference between your Dist+ enclosure and other Hamond/NSC-type enclosures? The weight and size proportions? I posted another thread wondering where these can be purchased which you posted in. Did they use a sturdier metal? Different spec of Aluminum perhaps?

Hi, no problem. I was in the same boat before I build my first clone. I was looking for a Bud or MXR box in the same proportions and shape. I settled on the Hammond 1590B. It's the same size in all LxWxH dimensions except the MXR style box has very rounded top edges and the Hammond's are sharper. It seems to me built pretty solid die-cast aluminum. I'm not sure how the weight compares. Here's a PDF datasheet with dimensioned drawings. You can rotate the 3D model too and see the shape from any angle: http://www.hammondmfg.com/pdf/1590B.pdf

I think the next closest box would be the Taiwanese B-size enclosures. I've never seen one in person to tell you if the measurements are exactly the same or not. I'd need to see a datasheet with drawings and what the cross-section looks like. I can't tell if the MXR Distortion+ box is aluminum or steel.

For my repair, optionally I 'could' make a smaller sized PCB, but I'd like to maintain a vintage replica PCB look. If I mod my broken MXR Distortion+ and add a LED and a 3PDT footswitch I need to check measurements carefully to see if a 9V battery would still fit inside. Did you know not all batteries are the same size?

[zombiwoof]

The early MXR pedals were BUD boxes, and I believe they are still making them.  I think no one ever talks about them because they are a little more expensive.

Al

[Steve Mavronis]

Check this out. My fried Dist+ PCB board dimension is 2.2" wide by 2.62" high, so in GIMP I scaled it to 660x786 (300dpi resolution) and perspective corrected to fit that. I used a 1/10" (30 pixels) grid pattern to visually guide me as I drew a layout using ExpressPCB. This is the first time I overlayed it on top of the PCB photograph so I'm pleased with the result. Now I see where to do a little bit of fine tuning! I want to try and make an exact as possible PCB replica copy to refurbish my broken pedal with.

[Govmnt_Lacky]

Steve,

Remaining as "authentic" as possible... Did the original Dist+ board have the wire markings, to show where they go, like you show in your layout? (i.e. D(3), O(3), etc.)

[Steve Mavronis]

Did the original Dist+ board have the wire markings, to show where they go, like you show in your layout? (i.e. D(3), O(3), etc.)

No it didn't. I just have them on there temporarily to remember what goes where with the wiring. I should remove them before I make the final etch pattern. I should of had those pad ls in yellow like the part shapes and values instead of in green for the bottom trace layer.

[Steve Mavronis]

Well, here's probably the final layout with component placement guide and PDF of just the board trace pattern at 300dpi to share with you. You can print it with Adobe Acrobat making sure any page scaling is set to none from the print dialog screen. Remember I print to transparency sheets and the pattern is a mirrored image on purpose because I flip over the sheet's printed side to make direct contact with te PCB material for UV exposure with no shadowing through the transparency plastic.

Not sure if I'll change the PCB text font in GIMP since I'm not trying to pawn off a counterfeit. I'm just making a replacement PCB to replace the original damaged fried one in my 1980 MXR Distortion+ so I'm thinking for this repair just to restore it to an original working state. I"ll probably won't have an IC socket either because I don't think there will be room to fit the lid on if I do. If I want to mod one I'll just make a custom DIY clone later on with my own PCB layout.

http://home.comcast.net/~snmavronis/distortion_plus_trace.pdf



Let me know if you have any questions. I'll update in the coming weeks with photos of the repaired unit.

[Steve Mavronis]

I was just updating my page (http://sites.google.com/site/snmavronis/neoclassic/mods-and-repairs) to chronicle my mods and repairs about fixing my Distortion+. I printed out the MXR Distortion+ PCB layout transparency tonight and gave it to my dad to etch a replica replacement board for me this week.

I was reading this Pedal Arena version change page (http://www.pedalarea.com/mxr_distortion.htm) and see the only differences between the original 'script' model, 'block logo' model, and first LED version was the op amp changing from a LM741CN to a UA741CP and the SPDT footswitch was changed to a DPDT for the LED and added DC jack.

Should I restore my block logo model to original condition or update it to a LED/DC jack model using a LM741CN as a 'best of' hybrid mod of the first 3 models?

[edvard]

The early MXR pedals were BUD boxes, and I believe they are still making them.  I think no one ever talks about them because they are a little more expensive.

Al

Actually, I've seen Bud boxes consistently $2 - 4 USD cheaper depending on where you get them.
I think Hammond has a wider-known reputation, so they get all the attention.
With so many others making even cheaper boxes (New Sensor, 4Site) Bud just kind of disappears into the static.

[Govmnt_Lacky]

The early MXR pedals were BUD boxes, and I believe they are still making them.  I think no one ever talks about them because they are a little more expensive.

Al

Actually, I've seen Bud boxes consistently $2 - 4 USD cheaper depending on where you get them.
I think Hammond has a wider-known reputation, so they get all the attention.
With so many others making even cheaper boxes (New Sensor, 4Site) Bud just kind of disappears into the static.

I just know that the Dist+ Bud box that I re-used is DEFINITELY heavier in weight BY FAR, than any of the Hammond, NSC, 4Site, etc. boxes that I have used recently.

[Steve Mavronis]

Yep, I was just showing my dad who stopped over last night how the MXR box is heavier than the Hammond 1590B.

[Steve Mavronis]

Here's a draft re-working of my take on a MXR Distortion+ schematic. Besides the familiar 'standard' distortion circuit inside the dashed box representing the PCB, my focus is on describing the offboard wiring as routed inside my broken MXR pedal. Is this too much info? I like the idea of looking at a thorough schematic diagram so you could wire up a pedal without seeing the real thing. I made a correction reflecting that the distortion pot's lug 1 is unused and connects internally to its own lug 2 to a ground wire.

[Steve Mavronis]

Here's the PCB etched and tinned made from my ExpressPCB layout which is a 1:1 copy of the MXR Distortion+ circuit board. I still have to clean up the board edges.Tonight or tomorrow I go over my father's to use his drill press to get the holes done. Then hopefully I can use this to replace the old fried one so I can refurbish and repair my broken pedal. I can't wait to hear how it sounds! I'll post a picture this weekend of my fixed pedal if I'm sucessful.

[Tony Forestiere]

Here's a PCB trace for a MXR Distortion+ that I traced from my fried 1980 pedal, as viewed from the component side.



Since I'm replacing the PCB with a non-original PCB and components anyway, do you think it wouldn't hurt to add a LED and DC Jack?

Here's what my broken MXR Distortion+ looks like now:



I hope you fixed the + battery wire Probably what fried it in the first place.

[Steve Mavronis]

I hope you fixed the + battery wire Probably what fried it in the first place.

Yep it probably shorted out and blew the board. The red AND black battery leads were splice twisted with no insulation! I have a whole new battery snap with wires to replace it. I might replace all the original wire because the 22 gauge I use looks thicker. Trying to decide if I should contact solder the 5 wires attached to the PCB like in the original or drill holes? But I'd like to preserve the original look as much as possible.

[Steve Mavronis]

Hey I have a question about those 5 wire pads at the top of the board. When I first made the replacement board layout I had the normal wire holes there. I forgot the real MXR board doesn't have the wire strands going through the board to the other side. I've since corrected the PCB layout I made in PDF format not to have holes there. On my board replacement, you won't see the hole spot since the wire and solder will cover it over. What is the best method to 'contact' solder wires directly to the pads? Should I just drill them through and solder the wires normally? Thanks.

[jaysg]

I'm not sure whether it was answered -- yes, you can fit a blue 3PDT into an MXR box without any problems.   I was looking at my '78-ish D+ vs. a 1590B and a taiwan B box.  The extra 1/16" depth is all in the bottom lid, oddly enough.   Years ago, I added a DC jack and LED at the top of the box.  Today, I would try to move the LED down below the knobs and see if the DC jack could fit next to the 3PDT...that seems more standard.