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Hints, Tips and Solutions (Do NOT post requests for help here) If you have any useful general hints and tips for vintage technology repair and restoration, please share them here. PLEASE DO NOT POST REQUESTS FOR HELP HERE!

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Old 1st Dec 2010, 1:50 am   #1
Graeme Murphy
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Default Cleaning gold plated edge connectors.

This may have been posted before but here goes....

I find that gold plated edge connectors do tarnish over time leading to noise, etc. Use an uncoloured (white) pencil eraser to remove the dirt and tarnish from the gold & finish off by removing the rubber "chaff" with a piece of soft cotton cloth. The edge connector will now be sparkling like new !
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Old 1st Dec 2010, 2:12 am   #2
paulsherwin
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Default Re: Cleaning gold plated edge connectors.

This was a standard technique used by computer field service engineers in the 70s and 80s. If the customer called field service out with random crashes or freezes, the first thing the engineer would do is remove all the cards from the backplane and clean the edge connectors with a vinyl pencil eraser. It really does work.
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Old 1st Dec 2010, 8:29 am   #3
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Default Re: Cleaning gold plated edge connectors.

if you really want to go over the top RS do a special rubber

i know as i have one !(so sad !)
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Old 1st Dec 2010, 9:18 am   #4
Mikey66
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Default Re: Cleaning gold plated edge connectors.

Ive got one of those RS rubbers you mention.
Its called GARRYFLEX RS 692 817
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Old 1st Dec 2010, 10:42 am   #5
Mike Phelan
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Default Re: Cleaning gold plated edge connectors.

Garryflex is an abrasive, though. I use it, but not for contacts and things.
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Old 1st Dec 2010, 10:50 am   #6
David G4EBT
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Default Re: Cleaning gold plated edge connectors.

Not wishing to sound too pedantic, but gold itself does not tarnish -certainly not in terms of oxidising, the most extreme example of which is rust on steel. Gold is one of the most stable metals, and the best conductor of even the tiniests of currents at extremes of temperature approx -150 - +200C, which is why of course its properties are favoured in electronics.

But of course, edge connectors aren't themselves gold - they're invariably copper or brass (or perhaps bronze) onto which an exceedingly thin film of gold has been electro-deposited.

If the base metal has first been nickle plated, (we've no way of knowing if it has) gold plated connectors won't tarnish even if the gold plating is as thin as 0.1 micron.

But if the base metal hasn't first been electroplated, that will have been on the grounds of cost, and it probably follows that the gold plating will be very thin indeed, compounding the felony. If the gold plating is so thin as to not form a complete film without pores, what you actually see isn't the gold 'tarnishing' but the base metal. (Copper, brass, bronze etc) migrating through the plating, arising from micro-porosity.

Any type of cleaning which uses abrasives will remove some of the already thin layer of gold, and though what remains may look bright and clean, it will inevitably be more threadbare than before, though the pores won't be visible to the naked eye.

If the contacts of any plugs that are plugged onto edge connectors are not themselves gold plated (tinned springy bronze for example) they themselves will deposit a layer of tarnish onto the gold plated edge connector.

Personally, I'd be more inclined to use a none abrasive chemical cleaner such as Goddard's Silver Dip, applied judiciously with a cotton bud (the buds of course - however gentle - are themselves abrasive).

I'm not doubting that the products sold for cleaning 'tarnish' will effect a cure, and of course the connectors aren't meant to be plugged on and taken off on a frequent basis. Just don't be tempted to look at your handywork through a microscope! I use a small light scope with a relatively modest level of magnification - 30x, which I use to check my home-brewed PCBs for broken or bridged tracks. However perfect they may seem to be to the naked eye, they're not a pretty sight at 30x and I dare say the same would be the case for gold-plated 'cleaned' edge connectors.

Not to drift too far off topic, although I've had my 30x light scope for 25 years, the same type is still available - for example, at this link:

http://www.arcare.com/Store/Products...ted-Lightscope

Great for spotting elusive dry joints too - one of the most useful litte gizmos I've ever bought!

Hope that's of interest.

David
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Old 1st Dec 2010, 11:48 am   #7
FIXITNOW
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Default Re: Cleaning gold plated edge connectors.

the one i have is Non metallic PCB cleaning scrub block RS Stock No. 216-2706

OverviewPCB Cleaning Scrub Block


•This fine grained non-metallic abrasive in an elastic binding agent is for dry cleaning or polishing copper laminates prior to printing or processing
Effective in cleaning metal contact areas on switches, relays, connectors etc.
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Old 2nd Dec 2010, 10:49 am   #8
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Default Re: Cleaning gold plated edge connectors.

Hi all,
Having been involved with gold plated edge connectors for some 10s of years, I have found the best solution to be to clean the board edge connectors themselves with IPA then a light spray of IPA and reinsert and remove several times to clean the sockets as well. Then if possible an air blast to remove excessive IPA. I have also used a very thin smear of silicone grease to inhibit further contamination.
In my radio/tv servicing days (long since past) turret tuners were the bane of our lives as most of them used silver plated contacts. We found that a thorough clean with Carbon Tetrachloride (gosh!) and later RBM contact cleaner followed by a thin smear of silicone grease worked wonders for up to two years. I have been an advocate of this method ever since.

John
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Old 3rd Dec 2010, 7:39 pm   #9
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Default Re: Cleaning gold plated edge connectors.

I've always used the coloured side of the eraser. This too for IC legs.
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Old 3rd Dec 2010, 7:47 pm   #10
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Default Re: Cleaning gold plated edge connectors.

Quote:
Originally Posted by John Caswell View Post
Having been involved with gold plated edge connectors for some 10s of years, I have found the best solution to be to clean the board edge connectors themselves with IPA then a light spray of IPA and reinsert and remove several times to clean the sockets as well.
John, I think we used to use trichloroethane in those days Ozone layer? What ozone layer?

I also used plenty of carbon tetrchloride as a kid. Either as "Thawpit" stain remover or in bottles from the chemist shop.
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Old 4th Dec 2010, 2:19 pm   #11
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Default Re: Cleaning gold plated edge connectors.

Working on shift in an RAF receiver hall we had some Marconi HF Rx's (as well as some valve rx'ers still in use) with pull out modules and we'd regularly have to pull them out clean with a rubber and spray with trich. As David says we we were probably just rubbing the gold off!

But don't use trich to clean perspex on a teleprinter
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Old 4th Dec 2010, 4:18 pm   #12
John Caswell
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Default Re: Cleaning gold plated edge connectors.

Hi all,
Ooh I had forgotten Trichloroethane, I think that came after Carbon Tet but not sure.
Thawpit now there's a name from the past.

John
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Old 4th Dec 2010, 5:37 pm   #13
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Default Re: Cleaning gold plated edge connectors.

We always burnished up the Gold edge connectors using, as previously mentioned, a large white soft pencil rubber.
We cut them into a specific shape to aid in their use (see attached)
Les
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Old 13th Dec 2010, 5:46 pm   #14
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Default Re: Cleaning gold plated edge connectors.

I always used methylated spirits but allow to dry before reconnecting to the mains (gently blowing on it evaporates it quickly).
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Old 24th Dec 2010, 1:49 am   #15
Graeme Murphy
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Default Re: Cleaning gold plated edge connectors.

I applied this to a Teradyne J259 system recently and I am pleased to report that it has not crashed since.
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