Cleaning badly corroded connectors

Discussion in 'General Electronics Chat' started by baronpork, Jan 31, 2015.

  1. baronpork

    Thread Starter Member

    Apr 16, 2013
    37
    1
    I'm restoring a commercial treadmill. It had been left in an unheated/damp space for some time and it obviously got corrosion issues. I can start it, it lights up but reports bad comms between motor control and power distribution, which suggests harness contact issues. Replacing connectors is not really an option.

    Connectors (sockets and plugs) are of molex pc power and atx type and approx same pin size. Plastic housing and dull silvery metallic parts. Any way to shock treat them to deox ? Some chemical ? I cant take the harness out without some major frame disassembly.

    Any help is appreciated.

    #Edit1# Treadmill in question is LifeFitness 9500HR Next Gen.
     
    Last edited: Jan 31, 2015
  2. #12

    Expert

    Nov 30, 2010
    16,267
    6,778
    The act of unplugging and re-connecting a connector is called, "reseating". (Check your computer repair bill for this charge.) Squirt them while they are apart and wiggle when you put them back together, still wet.

    Oh yeah, contact cleaner. NOT WD-40!!!
     
  3. baronpork

    Thread Starter Member

    Apr 16, 2013
    37
    1
    Was about to ask "squirt with what" ? :D

    Dont have any of that. Have some IPA and pure acetone. Can anything household'y be used for this ?
     
  4. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,521
    2,369
    Can you mechanically disconnect the track motor and/or incline motor and see if they run as they should, find out if/what is mechanical or electrical issues?
    De-natured alcohol if nothing else available.
    Max.
     
  5. #12

    Expert

    Nov 30, 2010
    16,267
    6,778
    No. That's why we get the big bucks. :D
     
  6. baronpork

    Thread Starter Member

    Apr 16, 2013
    37
    1
    Mechanically it looks fine. Main motor is spinning free, its 3ph 110v, cant really plug it in. need to check incline motor (how ? 18v drill battery ?).
     
  7. MrChips

    Moderator

    Oct 2, 2009
    12,436
    3,360
    Definitely DO NOT USE acetone.

    Most plastics will disintegrate in acetone.

    Rubbing alcohol is a better choice.
     
  8. baronpork

    Thread Starter Member

    Apr 16, 2013
    37
    1
    Hm, lift motor 110v as well.
     
  9. baronpork

    Thread Starter Member

    Apr 16, 2013
    37
    1
    (cant edit my own post above ?)

    Also, about acetone, yeah, wasnt thinking when typed that.
    Have some isopropyl alcohol, some white spirits (mineral spirits ?)

    More info on situation:
    This treadmill is a pet project of mine, got it for cheap with hopes of fixing it. And i do need it running :D Cant afford to fix it "properly" though, hence learning to do it myself...
    Today was a breakthrough as i managed to light it up, get into service menus etc. Initially it was only humming (transformer hum), no lights/sounds/errors. Just dead'ish.
    Had to replace some of primary power supply components just to get it to light up(2 caps and a TOP224Y pwm). Tested most of components (of pri psu) out of board. Also reflowed/soldered most of it, corrosion was bad. Good soldering practice, lots of fury inducing not wetting, inability to wick it off etc. Couple of times i was about to give up. Lots of reading was done.

    As it stands now:
    Now i have this "bad comm" problem. The power distribution (wax/lift/top panel control) pcb now lives, status leds light up (still to figure out meaning). Emergency stop works, i can hear relay engaging/disengaging when i remove magnet from front panel.

    Can up some pics of me messing about with this board.
     
  10. ian field

    Distinguished Member

    Oct 27, 2012
    4,413
    782
    The bloke over the road decided to collect an old pinball machine - it was near enough dead due to multiple dirty actuator contacts.

    I told him about the switch-cleaner used in the electronics servicing trade, and he decided that WD40 was close enough - AFAIK he got it all working.

    Often I use GT85, its like WD40 but PTFE enhanced - so far there's been no problems with the PTFE insulating anything that needs to be connecting.

    A word of warning - just about anything of recent manufacture will be infested with ABS plastics - extremely vulnerable to any hydrocarbon lubricants/solvents, the stuff just disintegrates!!! The "proper" switch cleaner is just as bad as any other solvent/lubricant.

    Silicone lubricant is safe on ABS plastics - unless its in an aerosol with hydrocarbom propellant.
     
  11. KJ6EAD

    Senior Member

    Apr 30, 2011
    1,425
    363
    CRC 2-26 or CRC 5-56 are my usual choices for contacts and connectors.

    Avoid silicone-bearing lubricants on switch and relay contacts since they form insulating glassy silicates in the presence of an arc.

    In my experience, corroded connectors carrying power will heat and scorch or melt their housings even after the application of contact cleaners and connectors carrying signals will never be reliable again. If these are typical .062" or .093" free hanging connectors, repinning is not that difficult or expensive. Ditto for .156" headers and wire receptacles.
     
    Last edited: Jan 31, 2015
  12. BReeves

    Member

    Nov 24, 2012
    412
    64
    Google "Bull Frog Electronic Cleaner". Great stuff for cleaning and preventing corrosion on contacts and connectors.
     
  13. baronpork

    Thread Starter Member

    Apr 16, 2013
    37
    1
    Hoo boy.

    Took apart top control panel as several keys werent working.
    Ribbon contacts were so corroded that there was nothing to clean really. Brushed oxide away till only plastic backing was left.
    Need advice on how to proceed with repair. any way to strip back this ribbon some 4-5 mm ? Never dealt with ribbons before.
    Its not a "micro" ribbon, no need for microscope, but it would be nice to know how to proceed before i ruin only chance at repairing it... :D
    Ribbon cannot be replaced as its a part of keyboard membrane. I'm thinking of cobbling up a makeshift 10pin connector on both sides, but how to
    connect/solder it to ribbon side ? Board side is easy - just a normal soldering would do.
     
  14. Reloadron

    Active Member

    Jan 15, 2015
    963
    232
    For actual corrosion I use baking soda and warm water with a stiff tooth brush, then dry with a paper towel and sometimes isopropanol alcohol to displace any remaining moisture. Once clean and dry I used to use Cramolin Red which I don't see much of anymore to leave a protective coating and avoid more corrosion.

    Ron
     
  15. Rocket.Man

    New Member

    Jan 1, 2012
    20
    7
    How bad is the rust? Light rust comes off with sand paper. Heavy rust comes off with muriatic acid. Use muriatic acid out side on a breezy day be sure to be on the upwind side. Do not breath acid fumes. Fumes will condence on your skin so make sure your on the up wind side all the time. Use a weed sprayer or paint brush to apply acid until rust is gone 5 to 20 minutes. Rinse with plenty of water to remove acid.

    This is how we clean metal parts at work, we have very large heated acid dip tanks and 2 clear water rinse dip tanks then a blow dryer and heat oven to dry parts before they are powder coated.
     
  16. Gdrumm

    Distinguished Member

    Aug 29, 2008
    684
    36
    An old trick used on batteries is to pour Coca-Cola on corroded terminals. It will bubble and fizzle, and the green stuff can be wiped away with a damp cloth. For ribbons, a stiff nylon brush might be needed.
    I've also scrapped ribbon connectors by gently dragging a razor blade across them.

    Can you post some photos, with something nearby for size comparison (like a dime or quarter, or dollar bill)?
     
  17. ian field

    Distinguished Member

    Oct 27, 2012
    4,413
    782
    A small commercial duty ultrasonic cleaner is great for cleaning corroded connectors - the solution should be made up to neutralise whatever (acid or alkali) caused the corrosion.

    A special offer ultrasonic cleaner from Maplin cost me about £15 - it didn't last long, but then I did wire up the timer so it ran continuously.

    Since then, a replacement from Lidl cost about £17 - it has a decent timer duration, so no need to wire it up. It seems a lot more vigorous than the Maplin one too.
     
  18. baronpork

    Thread Starter Member

    Apr 16, 2013
    37
    1
    I suspect this ribbon, and keypad membrane in general, is a total loss.
    Tried gentle scraping, went staight thru. Wiping on contacts with a cloth wiped most of contacts away (or rather oxide aftermath of corrosion). Keyboard was partly functional, but when i pulled it out for disassembly/cleaning most of what was left of actual conductor was left in the socket on the board...

    [​IMG]

    Scale is centimeters.

    membrane in question:

    [​IMG]

    Board end of things:

    [​IMG]
     
    Last edited: Feb 2, 2015
  19. Gdrumm

    Distinguished Member

    Aug 29, 2008
    684
    36
    I've used non-standard ribbon cable before, but it's tedious work.
    If you can find one that matches the width and number of strands, you might have a shot at fixing it.
    From the photos seen, the board and membrane look clean.

    Perhaps someone would have better advice.
     
  20. baronpork

    Thread Starter Member

    Apr 16, 2013
    37
    1
    No worries, i just "reverse engineered" it all, made one up from 12mm microswitches and some wire. Good to go... works fine.

    [​IMG]

    At this point treadmill works fine, all problems solved. However, i'm yet to find a good advice on corroded/gray solder joints. Had a lot of trouble desoldering and retinning corroded traces/pads. Wrecked one pad, needed to just solder a jump wire to fix it...
     
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