1977 MXR Distortion+ Restoration

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Re: 1977 MXR Distortion+ Restoration

Post by PLX »

harddriver wrote: Tue Aug 24, 2021 9:33 pm In the immortal words of NITRO..... You can hear the Distortion+ all over VH1................ :lol: :lol: :lol: :lol: :lol: :lol: :lol: :roll
I miss that guy.

I loved it when he would spam the VH Amp section on Metroamp forum with all that "sEcReT PeDaL" talk.

When they would tell him to STFU, he would come back with how Jose Arredondo told him "all the secrets" over the phone. :lol:
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Re: 1977 MXR Distortion+ Restoration

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PLX wrote: Tue Aug 24, 2021 9:54 pm]
he would come back with how Jose Arredondo told him "all the secrets" over the phone. :lol:
How dare Jose spill the beans to NITRO...... :evil: :evil:

Jose called me personally in 1987 at 18:59 CST and told me what the SeCreT pedal was.... and I'll never tell.. :roll:

BUWAHHHHAHAHAHAHAHHAHAHHAHAHAHHAHAHAHHAHAHAHHAHAHHAHAHAHAHHAHAHAHAHAHAHHA...... :lol: :lol: :lol: :lol:
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Re: 1977 MXR Distortion+ Restoration

Post by PLX »

Managed to source two different types of NOS(new old stock) 1N270 diodes for the clipping circuit.

Also, found NOS dipped tantalum caps.

Went ahead and ordered the 741 Op Amp, and 1/4 watt carbon-film resistors to replace the chipped ones on the board.. just in case. :roll:
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Re: 1977 MXR Distortion+ Restoration

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Cool project.

This cracked me up; the name of the color:
Sourced original paint color:
Seymour Of Sycamore® 16-212 "Old Equipment Yellow"
The Democratic Party is a criminal organization and the enemy within of the United States of America.
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Re: 1977 MXR Distortion+ Restoration

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lll wrote: Thu Aug 26, 2021 7:10 pm This cracked me up; the name of the color:
Sourced original paint color:
Seymour Of Sycamore® 16-212 "Old Equipment Yellow"
I know, right ?

A 44-year-old stomp box.

ironic :lol:
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Re: 1977 MXR Distortion+ Restoration

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While trying to order replacement potentiometers for this project, I had some difficulty sorting out the pot values.

All the schematics I found online show the pot values to be 1MΩ and 10KΩ, but the pots in my script logo 1977 Distortion+ measure 500KΩ and 56KΩ.. :x

Google search turned up this post from DIYStompboxes.com that cleared up everything.
DIYStompboxes wrote: After seeing discrepancies among various schematics, I spent way too many hours one night looking into the pot values for the D+. Seems the earlier "script" models used 500K for gain and 50K for volume, but I could never 100% verify that because the pots they used had part numbers without resistance values stamped on them. Maybe starting around 1980 or so, the pots were changed to 1M and 10K. The value of the gain pot doesn't really matter, the 1M is just able to get a little cleaner than 500K, but like you said the volume pot value does make a difference.

FWIW, the 50K volume pot actually measures right around 10K in circuit, this may have added to the confusion over the years, from people who own originals but don't want to unsolder anything.

(Edit: It's probably not just a coincidence that the "script" MXR Dyna Comp also used C500K and A50K pots.)

(Edit 2: Looking at some pics online, seems for at least a period in the mid- to late-70s, the part numbers stamped on the pots were MXR9471 for A50K and MXR9479 for C500K. You can see these part numbers in gut shots of both Dyna Comp and Dist+ pedals.)
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Re: 1977 MXR Distortion+ Restoration

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3 coats of "Old Equipment Yellow":

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Re: 1977 MXR Distortion+ Restoration

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Looking good... project is moving along...
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Re: 1977 MXR Distortion+ Restoration

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restored circuit board to original specs. replaced LEDs with NOS 1N270 germaniums. replaced chipped 1/4W carbon film resistors:

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Re: 1977 MXR Distortion+ Restoration

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