Digiplex 802 | FerrariChat

Digiplex 802

Discussion in '308/328' started by rjlloyd, Jul 30, 2021.

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  1. rjlloyd

    rjlloyd Formula Junior

    Jun 19, 2014
    447
    Brisbane, Australia
    Full Name:
    Richard Lloyd
    Hi all , looking for some advice please. I’ve been chasing a random dropping of a bank of cylinders (1-4) for a while. Been very hard to pin down as it usually corrects itself by the time I get the engine cover open etc. Anyway , with it being winter here in Australia , I’ve found it was far more likely to start on 4 cyls when cold. Yesterday morning as I was wiggling wiring looms etc , I decided to give the ECUs a thump and low and behold it immediately ran on 8. Do today I’m having a look at digiplexs and this is what they look like inside. My question is, is the white silicon compound factory ? Or would this suggest the ECUs have previously been worked on. I can buy changeovers from the UK but it’s not cheap. It’s not crank sensors and I know that the coil is not receiving a switching signal when it’s playing up. So it’s either ECU or wiring/plug at the ECU. Keen to hear any input. Cheers Image Unavailable, Please Login


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  2. mwr4440

    mwr4440 Five Time F1 World Champ
    Rossa Subscribed

    Jun 8, 2007
    57,977
    Bavaria, The 'Other' Germany
    Full Name:
    Mark W.R.
    #2 mwr4440, Jul 31, 2021
    Last edited: Jul 31, 2021
    The guy you might want to talk to is David:

    https://www.sarasotaitaliangarage.com/about/

    and subject specific:

    https://www.sarasotaitaliangarage.com/ferrari-parts/

    He and a partner rebuild these boxes using modern components. (Send them yours, you can get those boxes back). They can 'flash' various curves into them as well.

    His service is not 'Cheap,' but it is Much Cheaper than buying 'new to you' 30+ year-old 'dry rotted' electronic parts that are previously used or supposedly 'new.'

    Last pair I sent him, awhile back admittedly, my cost for rebuild was cheaper for BOTH BOXES than buying ONE 'New' BOX Retail, from the usual sources.

    I have several pairs of boxes with both US and Euro Curves sitting on a shelf rebuilt by him as spares. Another pair I recently picked-up real cheap, I gotta get off my butt and send.


    Tell him Mark in Germany sent you.

    [NO Affiliation other than a Very Happy Camper Customer].
     
  3. rjlloyd

    rjlloyd Formula Junior

    Jun 19, 2014
    447
    Brisbane, Australia
    Full Name:
    Richard Lloyd
    Thanks Mark

    Much appreciated, I’ll get in touch with David


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  4. mwr4440

    mwr4440 Five Time F1 World Champ
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    Jun 8, 2007
    57,977
    Bavaria, The 'Other' Germany
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    Mark W.R.
    Oh, and make sure your current problem (pun intended) is not in the wire loom or connector on it. They 'Go BAD,' too.

    Even if you find that as the issue, I'd still get the boxes rebuilt.

    It just a matter of time before they go 'Toes UP.'
     
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  5. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    Jan 11, 2001
    26,826
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    #5 Steve Magnusson, Jul 31, 2021
    Last edited: Jul 31, 2021
    Pretty sure that that rather sloppy post assembly potting is factory (and something that "evolved" over the years). Here's a shot of what I would guess is an early MED801A with some, but far less, potting compound applied:

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    And a shot of another (later?) MED801A with potting compound applied more like yours (note how they went to a different capacitor with a larger body so they could add a metal retaining spring clip, and gave it more of a specific place to mount and retain it):

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    Putting the big coil primary current switching Transistor inside the Digiplex ECU was a bit of a design mistake that they rectified on the following Microplex system (where that transistor can be replaced separately). +1 on working with David Feinberg for Digiplex repair/improvement.
     
  6. rjlloyd

    rjlloyd Formula Junior

    Jun 19, 2014
    447
    Brisbane, Australia
    Full Name:
    Richard Lloyd
    Thanks Steve, great info :)



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  7. rjlloyd

    rjlloyd Formula Junior

    Jun 19, 2014
    447
    Brisbane, Australia
    Full Name:
    Richard Lloyd
    So some success today. Refitted ECUs and car started up on 4. Was able to work out that by wiggling one of the plugs I could get it to run on 8. Then swapped plugs between ECUs and found the symptoms stayed with the same ECU. So that confirmed to me it was ECU and not wiring/plug. Pulled ECU apart again and with a bit of poking and prodding at the solder joints, found a dry joint on one of the pins. Resolve red and reassembled, all fixed. I will be contacting David Feinberg though. I’m very much an “as Enzotech intended” guy and don’t really stray from original , however Turtle Farmers fuse panel is simply awesome and I’d be just as happy with 21st century electronics inside the ECUs . Thanks everyone for the help Image Unavailable, Please Login


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  8. Badman

    Badman Formula 3

    Mar 4, 2007
    1,116
    Gotham City
    Full Name:
    Bruce Wayne
    Yes, that is factory, and they did indeed evolve quite a bit over the years. Near the end of the 801A/802A run of boxes they switched over to an entirely different style of connection for the PCB which had a black plastic frame all the way around the board and switched to a black RTV. They also modified the box castings a few times, tried using rubber gaskets for a while, stopped using the metal cover over the power transistor pocket, updated the power transistor mount, and eventually added a secondary PCB into the unit which converted the pulsed RPM pickup signal to a voltage signal before feeding it into the main board. Later units also sometimes had red paint applied to the top of the white RTV which covers the power transistor.

    Some of the Fiat and Lancia units, which used the same basic hardware but were labelled 4xx instead of 8xx (designating they were for 4 cylinder cars), had a few additional changes throughout their runs. But they're close enough that Fiat/Lancia cores can be rebuilt to make Ferrari units.

    When they went to the Microplex units for the 3.2 engines, they revised the design quite a bit and ended up with a much better unit, including moving the power transistor for the coils to external Bosch coil control units as Steve mentioned as well as running both banks off a single box.
     
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