Author Topic: Help on corroded connector  (Read 715 times)

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Offline Ultrapurple

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Help on corroded connector
« on: June 25, 2019, 09:56:51 am »
Hi all

I have an extremely elderly HP device that uses an Amphenol connector with a zillion soldered connections to a ribbon cable. The connector has seen better days - it has a nasty case of corrosion.

I have made a start on trying to redeem it using a fine abrasive (toothpaste!) but as the second photo shows, many of the contacts still look like what I believe many Americans envisage at the mention of a British person's teeth.

I have a limited number of cleaning options at my disposal. IPA and an ultrasonic bath are the main ones. Can anyone forecast whether I'm likely to get anywhere with either of these (separately, or together) or is there a better chemical solution I could use?

I am aware I'll probably have to re-plate what's left of the contacts because they're clearly pretty far gone, but I have ways to do that.
« Last Edit: June 27, 2019, 02:21:03 pm by Ultrapurple »
Rubber bands bridge the gap between WD40 and duct tape.
 

Offline BU508A

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Re: Help on corroded connector
« Reply #1 on: June 25, 2019, 10:03:45 am »
“Chaos is found in greatest abundance wherever order is being sought. It always defeats order, because it is better organized.”            - Terry Pratchett -
 

Offline Yansi

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Re: Help on corroded connector
« Reply #2 on: June 25, 2019, 10:13:36 am »
Just replace the damn connector.  :-+
 
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Offline 4thDoctorWhoFan

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Re: Help on corroded connector
« Reply #3 on: June 25, 2019, 10:26:53 am »
Dremmel tool with appropriate wheel attached.  Not sure what it's called.  Buffering wheel?
 

Offline Dubbie

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Re: Help on corroded connector
« Reply #4 on: June 25, 2019, 10:28:26 am »
Yeah, this looks like a 10min soldering job. Vs 30mis of cleaning and you still have an unreliable corroded connector.
 

Offline Ian.M

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Re: Help on corroded connector
« Reply #5 on: June 25, 2019, 10:37:22 am »
From the colour, those corrosion residue are copper salts. Cleaning and replating wont fix the pitting, which may well be severe enough to weaken the sprung contacts enough that they fracture.

I'm with Yansi.  There's no point in dicking round with nasty chemicals, abrasives etc. for however many days it takes to get a substandard result. Replacing the connector (including desoldering)  shouldn't take over an hour*, assuming you are *somewhat* competent with a soldering iron and can clamp or jig the connector and cable lined up so you don't have to fight every wire to get it in place.  There's only 64 of them . . . .

* Dubbie is a little over-optimistic - 9 seconds per wire isn't very long to desolder them all then position and resolder each wire.  Maybe if you work in a sweatshop doing cable looms as piecework  you could be that fast . . .
 

Offline Dubbie

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Re: Help on corroded connector
« Reply #6 on: June 25, 2019, 10:45:00 am »
Yeah, maybe that is a little optimistic :D let’s say 30mins.
 

Offline Ultrapurple

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Re: Help on corroded connector
« Reply #7 on: June 25, 2019, 10:56:41 am »
Thanks for these suggestions.

I would replace the connector if I could find one anywhere! It appears to be an Amphenol 57-10640(438) and I guess the '8343' is a date code telling me it's ~35 years old.

I have done some looking for a replacement but so far with little success. Indeed, the one I've shown here IS the replacement (a replacement cable assembly). I don't have a photo of the first plug in all its original mankiness but the second photo is the socket it came out of. It looks a bit like Bender six years after he lost his toothbrush.
« Last Edit: June 25, 2019, 02:30:37 pm by Ultrapurple »
Rubber bands bridge the gap between WD40 and duct tape.
 

Offline BU508A

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Re: Help on corroded connector
« Reply #8 on: June 25, 2019, 11:15:34 am »
“Chaos is found in greatest abundance wherever order is being sought. It always defeats order, because it is better organized.”            - Terry Pratchett -
 
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Offline Ultrapurple

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Re: Help on corroded connector
« Reply #9 on: June 25, 2019, 11:26:58 am »
@BU508A - thank you! I tried the Mouser site (and RS, Farnell...) without any success, probably simply due to ineptitude on my part.

I will have a good look at the connectors that came up and see what looks like the best option.
Rubber bands bridge the gap between WD40 and duct tape.
 

Offline shakalnokturn

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Re: Help on corroded connector
« Reply #10 on: June 25, 2019, 01:17:05 pm »
I'll be interested in the conclusions I have a HP 8350B+83525B that I started restoring a few years back.
Funnily the 64 way connectors were in similar condition, the 8350B had suffered corrosion around the larger capacitor bunch and near fan.
At the time I had a quick look for replacement connectors and resolved to clean the existing ones.
 

Offline Ultrapurple

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Re: Help on corroded connector
« Reply #11 on: June 25, 2019, 01:28:32 pm »
By a remarkable coincidence the connector is on a HP 11869A that I (want to) use to run an 86590C (2-18.6GHz) in an 8350B.

The first 8350B - with the socket photographed above - is pretty much scrap, I suspect, though I'm keeping it for parts for the time being in case its replacement has a hissy fit.
Rubber bands bridge the gap between WD40 and duct tape.
 

Offline Ultrapurple

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Re: Help on corroded connector
« Reply #12 on: June 26, 2019, 03:26:10 pm »
I gave it my best shot and ... it worked.

First I put the connector in an ultrasonic bath, to very little effect.
Then I replaced the water with warm IPA (yes, I'm aware of the dangers; I took appropriate precautions). Again, not very much action.
Finally I made up a strong, warm solution of citric acid and put that in the ultrasonic cleaner. Voila - it cleaned most of the corrosion off.

The last steps were a good rinse in plain water and a final slosh of IPA. The plating on the pins has clearly had it (but I can re-plate); the most important thing is that it works well enough for now and I have the use of my test instrument, at least for a while. Given that I didn't use it in the last ten years and only have one job for it at the moment, that's good enough.

Thanks for all the help, everyone.
« Last Edit: June 26, 2019, 08:08:14 pm by Ultrapurple »
Rubber bands bridge the gap between WD40 and duct tape.
 
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Offline Dubbie

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Re: Help on corroded connector
« Reply #13 on: June 27, 2019, 07:20:23 am »
A happy ending to the thread [emoji3]
 

Offline cvanc

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Re: Help on corroded connector
« Reply #14 on: June 27, 2019, 01:21:11 pm »
Good sleuthing  :-+

Citric acid, huh?  I woulda never thought of that.  Is this a generally applicable idea for heavily gunked up contacts?
 

Offline Ultrapurple

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Re: Help on corroded connector
« Reply #15 on: June 27, 2019, 02:13:57 pm »
I can't say whether citric acid is a general solution (sorry!) for contact issues. I used it because I had it handy - I'd bought a couple of pounds of crystals to give my dishwasher the de-scaling of its life and I simply had a few ounces left in the bag.

A note of caution: turning up at work with a large, unmarked baggie full of white powder can lead to some awkward questions (and a lot of people suddenly deciding they want to be your best friend).
« Last Edit: June 27, 2019, 02:17:51 pm by Ultrapurple »
Rubber bands bridge the gap between WD40 and duct tape.
 
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Offline emece67

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Re: Help on corroded connector
« Reply #16 on: June 27, 2019, 08:16:02 pm »
Sometimes I've used cleaning vinegar to clean corroded or battery-leaked contacts. Maybe weak acids do the trick.

Regards.
Information must flow.
 

Offline TERRA Operative

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Re: Help on corroded connector
« Reply #17 on: June 28, 2019, 05:32:41 am »
I have also found white vinegar good for cleaning this sort of gunk.


Now, you should make sure to store that cable in a zip-lock bag with a desiccant pack to keep it all fresh and delicious. :)
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