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Removing Potting Compound Gone Bad — Parallax Forums

Removing Potting Compound Gone Bad

ercoerco Posts: 20,257
in General Discussion
I found my 1983-era Fairchild Elecronic Ignition and may consider re-using it, but the potting compound has become a tarry mess. Barely a liquid, like sticky molasses, yuck. Sticks to everything. I tried removing with alcohol, engine cleaner, and carburetor cleaner (pretty nasty stuff that evaporates quickly) but nothing works. I haven't tried water yet...

Perhaps the experienced brain trust here can shed some light on some bizarre solvent or process that may help. Oatmeal? Peanut butter? Canned beets? Goat urine? Heat? Rain dance? I'm wide open.

Comments

  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    Just put it in a bell jar, and let it drip:

    https://en.wikipedia.org/wiki/Pitch_drop_experiment

    May take awhile ...

    -Phil
  • ercoerco Posts: 20,257
    Capital idea! At least that will allow one part of the Corvair to live on long after the rest has rusted into oblivion...
  • ercoerco Posts: 20,257
    Here's a similar unit, still vacuum sealed in the package, same tar-ry potting mess. https://www.ebay.com/itm/NOS-Fairchild-Solid-State-Breakerless-Electronic-Ignition-Kit-1968-74-Volkswagen-/264635887083
    s-l1601.jpg
    1200 x 1600 - 353K
  • ercoerco Posts: 20,257
    edited 2020-08-02 20:57
    I better stick with the new Pertronix module I bought. I bet @publison (Jim) has used those!
  • PublisonPublison Posts: 12,366
    I usually hit it with a heat gun and shovel out with a pick.
  • TubularTubular Posts: 4,705
    Industrial solvent. We use Episolve but I can't find much info on it on the net

  • ercoerco Posts: 20,257
    edited 2020-08-02 21:10
    Boiling water?


  • ercoerco Posts: 20,257
    I figured this is way beyond Simple Green and Purple Power... This calls for a harsh, non-green, toxic solution.
  • Duane DegnDuane Degn Posts: 10,588
    I recently purchase an electric skateboard. When it stopped working after about a week of use, I opened it up to look inside. Everything was covered with black potting material.

    SkateboardPottingBefore.jpg

    That's the battery management system with the wires poking out.

    The manufacture sent a new battery and while waiting for the new battery, I started digging out the black potting material looking for things to fix.

    I found a bunch of things to fix. Much of what was wrong was caused by the potting material. It had seeped into the connector contacts. Here's a look at the cleaned up BMS.

    SkateboardPottingAfter.jpg

    A couple of balance leads had broken. I fixed these wires and figured, I'd charge the cells with my hobby battery charger rather than using the board's BMS.

    I wasn't very hopeful, but I decided to try to fixed the BMS. I removed each of the crimped connectors and scrapped off the black potting material. After cleaning each pin and each connector, I finally managed to get the the BMS working again.

    If they hadn't added the potting material, the BMS would likely not have stopped working. The potting material also make fixing broken balance lead wires much harder. If the potting material hadn't been added, it's still possible one of the wires could have broken. Fixing a broken wire without having to dig it out of the potting material would have been really easy. I would have likely fixed the thing without bothering to contact them. As it was, I wasn't sure I could fix the problem and accepted the offer of a replacement battery pack.

    Since I got the old pack working, I'll be using the replacement pack in a board I'm putting together from parts.

    BTW, those electric skateboards are as much fun as they look.
    SkateboardPottingBefore.jpg
    1363 x 1022 - 441K
    SkateboardPottingAfter.jpg
    1363 x 1022 - 411K
  • frank freedmanfrank freedman Posts: 1,983
    And then you have the exact opposite in the case of the MedRad (Dual) Stellant contrast injector. Contrast media in one syringe, Saline in the other. Each can leak or otherwise / causes resulting or saline or contrast intrusion into the case. The result is a corroded and highly expensive replacement of parts that had they chosen to properly protect the boards say conformal coatings such as we encountered in military equipment, the systems would actually be able to handle the harsh chemistry that can get inside. Case of Smile where you likely don't need it vs. Smile not present when it should be.......
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    Duane Degn wrote:
    I recently purchase an electric skateboard.
    I'm just impressed that you can actually ride an electric skateboard!

    -Phil
  • Duane DegnDuane Degn Posts: 10,588
    Phil Pilgrim (PhiPi) wrote: »
    I'm just impressed that you can actually ride an electric skateboard!

    -Phil

    I figure it had been about 40 years since I had last ridden a skateboard.

    Riding the board requires all sorts of muscles my sedentary body isn't used to using.
    A cruise around the block was all I could manage the first couple times I used it. As with most things, it has gotten much easier to use with practice.
    It has been every bit as much fun as I had hoped. My wife also likes to ride it and has commented on how fun it has been to use.

    I'm building a second board so we can ride at the same time. The second board will use a pair of VESCs so I can more easily use the motors and controllers in robotic projects.
  • ercoerco Posts: 20,257
    NICE! Great to hear from you Duane, and that you and the wife are safe and healthy. Now please STAY that way on your skateboard, Boss! The last thing you need is a trip to the ER or hospital these days. My wife had appendicitis in May and had to spend half a week in the hospital... Fortunately all went well but these days you never know!
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