Electra MPC Module Schematics

Discussion regarding early stompbox technology: 1960-1975 Please keep discussion focused and contribute what info you have...
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jsrfo
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Post by jsrfo »

Does anyone have schematics or traces of the old Electra Guitar MPC modules? Just picked up a nice MPC guitar, and would like to attempt to make a module board, but would like to first see the thought process behind them, as the guitar uses one 150K pot to control one parameter on the effect. Pretty simple, I'd assume.

Any help would be appreciated. I'd even buy a broken or functional module to work from.

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Post by Nocentelli »

Some superb (and possiblly trace-able) gutshots here:

http://www.rivercityamps.com/electra/modules.php
vanessa wrote: 20 Aug 2007, 17:51 You can't arrest someone for reverse engineering something.

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Post by Axldeziak »

Looking through their forum it seems the phaser circuit was an original E-H Small Stone using CA3094 OTA.

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Post by jrod »

Nocentelli wrote:Some superb (and possiblly trace-able) gutshots here:

http://www.rivercityamps.com/electra/modules.php
The Overdrive looks to be basically the "Electra Distortion" schematic that's been floating around for years, but without the clipping diodes.

For the Dynamic Fuzz though the PCB trace side doesn't match up with the components.

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Post by Dr Tony Balls »

Dont have any schematics, per se, but I can chime in with some info. Awhile back a friend sent me two MPC modules in hopes that could get them working. The problem being that I dont have an MPC guitar to test them on. So I built a little pedal that could accept MPC cartridges for testing and use. Bought a 10 pin edge connector and just hooked it up outside a stompbox like so:

Image

One cart was a distortion unit that I got working. The other was a phase shifter that I couldnt get to the bottom of so instead I set out to build a replacement circuit. You could print a PCB for this if you want, but I found that 0.15" pitch vero board was a close enough match for the edge connector. You just have to cut it to size and cut/file shoulders by the connector. Wound up putting a Magnavibe circuit on one:

Image

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Post by jsrfo »

I have just designed replacement PCB's for the Power Overdrive and the Dynamic Fuzz, and they work. So, now I need to figure out module boxes for these. Made one of each, and they work just fine. I intend to do a different overdrive as well, as I started out with those two original, simple circuits.

If anyone has suggestions on the module boxes, it would be appreciated.I thought about 3D printing.

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Post by jsrfo »

So, I am in the process of obtaining 3D printed cases for module boards. Wish I knew how to embed a picture, but they're basically the same size as the originals, only dark grey.

I have my own overdrive, sold as a pedal called the El Mo, built into a card, and it works pretty nicely. Three trim pots to adjust the module level output, bass and treble. The guitar pot controls the gain, which also adds some level. I've found that setting the tones up allow for brightening up the neck pickup on my X330. I set the tone the way I like it on the bridge pickup with the tone pot at "5", and then I can roll of some highs on the bridge if I want, or add some highs on the neck pickup. Also, the ability to adjust the output level of the card provides the ability to set unity volume with the module turned on at any desired point on the module control pot, unlike the originals, which some actually had to be turned up fairly far for unity.

Anyway, I can currently build cards for the Electra Power Overdrive, my custom OD, and an Electra Distortion circuit with two germanium diodes at this point.

Looking if anyone has a true gut shot or schematic for the Dynamic Fuzz Module, or any of the other modules, I'd like to see if I could make boards for them as well.

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Post by pinkjimiphoton »

jsrfo wrote: 12 Jan 2020, 22:24 So, I am in the process of obtaining 3D printed cases for module boards. Wish I knew how to embed a picture, but they're basically the same size as the originals, only dark grey.

I have my own overdrive, sold as a pedal called the El Mo, built into a card, and it works pretty nicely. Three trim pots to adjust the module level output, bass and treble. The guitar pot controls the gain, which also adds some level. I've found that setting the tones up allow for brightening up the neck pickup on my X330. I set the tone the way I like it on the bridge pickup with the tone pot at "5", and then I can roll of some highs on the bridge if I want, or add some highs on the neck pickup. Also, the ability to adjust the output level of the card provides the ability to set unity volume with the module turned on at any desired point on the module control pot, unlike the originals, which some actually had to be turned up fairly far for unity.

Anyway, I can currently build cards for the Electra Power Overdrive, my custom OD, and an Electra Distortion circuit with two germanium diodes at this point.

Looking if anyone has a true gut shot or schematic for the Dynamic Fuzz Module, or any of the other modules, I'd like to see if I could make boards for them as well.
where ya getting the boxes printed? will you have the files for them? i gotta bud asked me if i could build him some, so curious
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Post by modman »

Nocentelli wrote: 10 Nov 2019, 16:56 Some superb (and possiblly trace-able) gutshots here:
http://www.rivercityamps.com/electra/modules.php
This site is down, but I was able to retrieve the guts shots of the Distortion module from the waybackmachine... There are no diodes is this 'original' Electra Distortion!

mpc5_ft.jpg
mpc5_ft.jpg (13.32 KiB) Viewed 2027 times
mpc5_bk-2.jpg
mpc5_bk-2.jpg (18.53 KiB) Viewed 2027 times
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Post by pinkjimiphoton »

that's the overdrive unit, the distortion uses a diode clipper, but is the same circuit

here's the phaser guts
phaser guts 1
phaser guts 1
scan0004.jpg (98.11 KiB) Viewed 2021 times
phaser guts 2
phaser guts 2
scan0001.jpg (32.98 KiB) Viewed 2021 times
here's more from the archive:
mpc1_ft.jpg
mpc1_ft.jpg (18.75 KiB) Viewed 2021 times
mpc1_bk.jpg
mpc1_bk.jpg (22.13 KiB) Viewed 2021 times
mpc5_ft.jpg
mpc5_ft.jpg (13.32 KiB) Viewed 2021 times
mpc5_bk1.jpg
mpc5_bk1.jpg (18.53 KiB) Viewed 2021 times
mpc5_bk.jpg
mpc5_bk.jpg (18.53 KiB) Viewed 2021 times
mpc2_ft.jpg
mpc2_ft.jpg (13.88 KiB) Viewed 2021 times
wir2.png
wir2.png (124.2 KiB) Viewed 2021 times
wir1.png
wir1.png (56.11 KiB) Viewed 2021 times
Electra MPC Module 1 - Phase Shifter.pdf
(868.78 KiB) Downloaded 80 times
Electra MPC Module 2 - Dynamic Fuzz.pdf
(668.06 KiB) Downloaded 94 times
Electra MPC Module 3 - Treble Bass Expander.pdf
(425.51 KiB) Downloaded 69 times
Electra MPC Module 4 - Tank Tone.pdf
(400.9 KiB) Downloaded 70 times
Electra MPC Module 5 - Power Overdrive.pdf
(543.21 KiB) Downloaded 74 times
Electra MPC Module 6 - Filter Follower.pdf
(952.53 KiB) Downloaded 73 times
Electra MPC Module 7 - Automatic Wah.pdf
(340.12 KiB) Downloaded 70 times
Electra MPC Module 8 - Tube Sound.pdf
(322.11 KiB) Downloaded 90 times
Electra MPC Module 9 - Octave Box.pdf
(293.67 KiB) Downloaded 68 times
Electra MPC Module 10 - Flanger.pdf
(740.08 KiB) Downloaded 71 times
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Post by pinkjimiphoton »

more
Electra MPC Module 11 - Frog Nose.pdf
(315.03 KiB) Downloaded 69 times
Electra MPC Module 12 - Compressor.pdf
(859.47 KiB) Downloaded 62 times
mpc_2.jpg
mpc_3.jpg
electra distortion schem.jpg
electra distortion schem.jpg (15.7 KiB) Viewed 2021 times
1981pricelist-4.jpg
sh_M06_2.jpg
sh_m06_3.jpg
this is most of what i've found so far. i'm building a couple of the cards for a friend, so hopefully these will help someone else.
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Post by modman »

pinkjimiphoton wrote: 11 Jul 2021, 13:05 that's the overdrive unit, the distortion uses a diode clipper, but is the same circuit
You are right: it is the Electra Overdrive module -- but as your list show there is never was an "Electra Distortion" module... or is it the Tube Sound module?
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Post by pinkjimiphoton »

it appears what i call electra distortion module was the tube sound module. add diodes, and instant tube sound lol
i'll be working on some layouts for cards for a few things for my friend who has an electra guitar..
planning on building him the od and distortion, as well as maybe an envelope and phaser. i think i can squeeze a p45 into one of the perf boards he got.
they use 10 pin edge connectors. hopefully the stuff i posted earlier will be useful for someone down the road bro
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Post by jsrfo »

I've build the "Electra Distortion" circuit schematic above into a module card. It's the one with the output pot.

Is there a back shot of the photo with the three transistors on it? Do you know what that one is?

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Post by jsrfo »

This is my custom overdrive module for the MPC guitars. The circuit is my own, and I designed the printed circuit edge card. I also print my own module cases.

Image

I also did an exact electrical copy of the MP5 Power Overdrive circuit, a Bass Fuzz, Boost, and that Electra Distortion circuit referenced as the Tube Sound above. I did a single chip chorus. It works, but I don't like it. Need to use the two chip version I suspect.

Currently working on a Univox Super Fuzz/Ibanez 59 Fuzz module.

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Post by pinkjimiphoton »

hey bro, pm me some contact info? i gotta bud would probably buy some of these from you.
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