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| Re: Just for some light entertainment [message #373982 is a reply to message #373979] |
Mon, 24 September 2018 10:18   |
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Originally posted by: Anthony Adverse
> Not sure I'd want to sandpaper the slots though - especially with old
> gold plated connectors...
If you were going to get that physical I'd be looking for a bit of scotchbrite. Even 4/800 grit sandpaper would be coarse enough to chew your gold off... 1200+ would be a better suggestion.. still not where I'd want to go either.
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| Re: Just for some light entertainment [message #373988 is a reply to message #373982] |
Mon, 24 September 2018 14:38 |
Michael J. Mahon
Messages: 1770
Registered: October 2012
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Anthony Adverse <the.ertceps@gmail.com> wrote:
>> Not sure I'd want to sandpaper the slots though - especially with old
>> gold plated connectors...
>
> If you were going to get that physical I'd be looking for a bit of
> scotchbrite. Even 4/800 grit sandpaper would be coarse enough to chew
> your gold off... 1200+ would be a better suggestion.. still not where I'd
> want to go either.
>
Most gold plated connectors and edge contacts are rated reliable for about
50 insertions and removals, after which scratches in the gold plating
penetrate the gold and expose more reactive metals.
Sandpaper, or practically any hard abrasive, is definitely a no-no. Even an
“ink eraser” is too much.
--
-michael - NadaNet 3.1 and AppleCrate II: http://michaeljmahon.com
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| Re: Just for some light entertainment [message #374045 is a reply to message #373988] |
Tue, 25 September 2018 16:49 |
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Originally posted by: Michael Mann
> Most gold plated connectors and edge contacts are rated reliable for about
> 50 insertions and removals, after which scratches in the gold plating
> penetrate the gold and expose more reactive metals.
>
> Sandpaper, or practically any hard abrasive, is definitely a no-no. Even an
> “ink eraser” is too much.
>
> --
> -michael - NadaNet 3.1 and AppleCrate II: http://michaeljmahon.com
Fascinating reply, the 50-insertion factoid. Can you point us to a source for that? I'd like to read more about that.
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| Re: Just for some light entertainment [message #374085 is a reply to message #374045] |
Wed, 26 September 2018 18:35 |
Michael J. Mahon
Messages: 1770
Registered: October 2012
Karma: 0
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Senior Member |
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On 9/25/2018 1:49 PM, Michael Mann wrote:
>> Most gold plated connectors and edge contacts are rated reliable for about
>> 50 insertions and removals, after which scratches in the gold plating
>> penetrate the gold and expose more reactive metals.
>>
>> Sandpaper, or practically any hard abrasive, is definitely a no-no. Even an
>> “ink eraser” is too much.
>>
>> --
>> -michael - NadaNet 3.1 and AppleCrate II: http://michaeljmahon.com
>
> Fascinating reply, the 50-insertion factoid. Can you point us to a source for that? I'd like to read more about that.
My source was a senior hardware designer at HP, previously Amdahl,
previously IBM. We were discussing construction methods for computer
prototypes (and the need to make frequent changes in them) when he
mentioned the 50-insertion rule for reliable gold-plated edge connectors.
He explained that it was a result of both the thinness of the usual
"flash" gold plating and the presence of abrasive dust particles, which
scratch through the plating to base metal, leading to corrosion and
electrical intermittency.
Before replying, I did some web research on gold edge connectors, and I
found a pretty wide range of opinion! Some say they are good for about
1000 insertion/removal cycles, citing some testing. But the testing is
usually done in a clean, sometimes lubricated, environment, by cycling
the same PCB/edge connector pair repeatedly. This is a good
controllable environment, but not very representative of the real world.
If you think about it, it's pretty clear that the method of plating, the
thickness of the gold (and any alloying metal), the underlay metal (just
copper, or flash nickel), the contact pressure of the connector, and the
cleanliness of the environment are all important.
Given the mainframe background of my colleague, it's likely that he was
using conservative guidelines for PCB cards installed in a forced-air
cooled environment, which deposits ample quantities of environmental
dust. He also had experience with faults being introduced by "benign"
swapping of cards in the field.
While an Apple II is hardly a high-reliability device, a conservative
estimate of edge connector life is probably warranted by the relatively
dusty environment in which most are stored and used. This is
particularly true since the edge connectors are not shrouded in any way
when they are not in use.
BTW, I turned up another interesting and relevant factoid in my search:
gold-gold is very good, tin-tin is good, but gold-tin is trouble! This
is problematic since so many inexpensive Apple peripheral cards have
tinned contact fingers, not gold.
It seems that the electrical integrity of metal-to-metal contacts is an
advanced topic because of the many surface effects--there are lots of
research papers on the topic! And whether the contacts "wipe" together
regularly or whether they wipe once and stay for a long time is also a
consideration. Wiping is good, until wear changes the surface for the
worse. Contacts that do not wipe after insertion can be quite stable if
undisturbed, but can be problematic if stressed (even thermally) or
vibrated.
Thanks for the excuse to go down this rabbit hole! ;-)
--
-michael
NadaNet 3.1 for Apple II parallel computing!
Home page: http://michaeljmahon.com
"The wastebasket is our most important design
tool--and it's seriously underused."
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| Re: Just for some light entertainment [message #374086 is a reply to message #374085] |
Wed, 26 September 2018 18:52 |
bpiltz
Messages: 78
Registered: October 2012
Karma: 0
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> BTW, I turned up another interesting and relevant factoid in my search:
> gold-gold is very good, tin-tin is good, but gold-tin is trouble! This
> is problematic since so many inexpensive Apple peripheral cards have
> tinned contact fingers, not gold.
Yes, gold-tin is very bad, since it involves some sort of redox reaction between to two (chemically-incompatible) metals. Back in the '90s, cheap Taiwanese motherboard manufacters and memory manufacturers got in trouble / exposed for mixing tin and copper contacts as a cheapening measure to save a few cents per unit... Not good.
Your 50 insertions rule has me quite worried, as I frequently put my external USB 3.5" hard drives to USB-SATA adapters in order to play films directly off my HDs into my Blu-ray's USB ports... I've done it 100s of times with no problem so far, but I know it's only a matter of time before the gold connections wear off due to frequent insertion and ejection... Or, am I 'safe'?
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| Re: Just for some light entertainment [message #374087 is a reply to message #374086] |
Wed, 26 September 2018 19:28 |
sicklittlemonkey
Messages: 570
Registered: October 2012
Karma: 0
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Senior Member |
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On Thursday, 27 September 2018 10:52:37 UTC+12, bpi...@gmail.com wrote:
> Your 50 insertions rule has me quite worried, as I frequently put my external USB 3.5" hard drives to USB-SATA adapters in order to play films directly off my HDs into my Blu-ray's USB ports... I've done it 100s of times with no problem so far, but I know it's only a matter of time before the gold connections wear off due to frequent insertion and ejection... Or, am I 'safe'?
When I've mated systems like that I always tried to arrange the swap around replaceable USB cables - not ones integral to the device on either end. Type A are rated for 1,500 insertion cycles. Micro and Type C are rated for 10,000.
Cheers,
Nick.
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| Re: Just for some light entertainment [message #374093 is a reply to message #374087] |
Wed, 26 September 2018 20:15 |
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Originally posted by: Matthew Power
This thread has me wondering if some type of conductive grease should be applied to the pins on cards when people (like me) constantly swap different cards out on a 35 year old motherboard? Actually, as I'm typing this I think grease of any kind tends to trap abrasive dust.
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| Re: Just for some light entertainment [message #374119 is a reply to message #373968] |
Thu, 27 September 2018 22:05 |
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Originally posted by: James Davis
I read somewhere, once or twice, that pinching and sliding a piece of typing paper over (down, in the direction of the contacts) on a peripheral card's edge connector was sufficient to clean them. And, that doing something similar in the peripheral card slot, and vacuuming them out (with one of those battery operated keyboard vacuums) was sufficient to clean them.
20 years ago, I used a vacuum cleaner once to blow out 20 years of dust from my Apple and my PC. It took me a week to get that dust out of the rest of my house! Should of done it outside. :-)
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| Re: Just for some light entertainment [message #374124 is a reply to message #374119] |
Fri, 28 September 2018 02:29 |
Your Name
Messages: 914
Registered: September 2013
Karma: 0
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Senior Member |
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On 2018-09-28 02:05:55 +0000, James Davis said:
>
> I read somewhere, once or twice, that pinching and sliding a piece of
> typing paper over (down, in the direction of the contacts) on a
> peripheral card's edge connector was sufficient to clean them. And,
> that doing something similar in the peripheral card slot,
Best option is to use some rub gently with some cleaning alcohol.
A very gentle rub which some very fine sandpaper can help badly
corroded contacts, but you have to be extremely careful since rubbing
too hard will of course just destroy them.
Another option can be to use small separate strips of aluminium / tin
foil folded over the card edge where each of the contacts are ... but
it's not really advisable since the foil can get stuck in the slot when
you take the card out again!
> and vacuuming them out (with one of those battery operated keyboard
> vacuums) was sufficient to clean them.
> 20 years ago, I used a vacuum cleaner once to blow out 20 years of dust
> from my Apple and my PC. It took me a week to get that dust out of the
> rest of my house! Should of done it outside. :-)
You aren't meant to use a vacuum cleaner to blow (or suck) dust out of
electronics. The plastic nozzles can create static electricity, which
of course can destroy things like the chips in electronic devices.
You also don't blow it out yourself since your mouth will add saliva
droplets, and of course moisture is also a no-no inside elctronic
devices.
You're meant to use one of those cans of compressed air, which
apparently don't create static (somehow, since they too usually have
plastic nozzles!) nor add moisture.
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| Re: Just for some light entertainment [message #374125 is a reply to message #374087] |
Fri, 28 September 2018 03:32 |
Michael J. Mahon
Messages: 1770
Registered: October 2012
Karma: 0
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Senior Member |
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Nick Westgate <nick.westgate@gmail.com> wrote:
> On Thursday, 27 September 2018 10:52:37 UTC+12, bpi...@gmail.com wrote:
>> Your 50 insertions rule has me quite worried, as I frequently put my
>> external USB 3.5" hard drives to USB-SATA adapters in order to play
>> films directly off my HDs into my Blu-ray's USB ports... I've done it
>> 100s of times with no problem so far, but I know it's only a matter of
>> time before the gold connections wear off due to frequent insertion and
>> ejection... Or, am I 'safe'?
>
> When I've mated systems like that I always tried to arrange the swap
> around replaceable USB cables - not ones integral to the device on either
> end. Type A are rated for 1,500 insertion cycles. Micro and Type C are rated for 10,000.
>
> Cheers,
> Nick.
>
An excellent strategy!
And non-edge connectors are designed for their intended usage lifetime, so
USB connectors will likely have a thicker, electroplated gold layer.
One important aspect I didn’t mention is the effect of “wet” (current
carrying) or “dry” (non-current carrying) circuit applications.
Current flow affects electromigration and rates of corrosion, since no
connector has zero contact resistance and therefore a voltage appears
across the connector contacts. Current-induced micro-arcing also “clears”
opens caused by thin oxide layers or foreign matter. If contacts are
designed to interrupt current flow (either from unmating or from contact
bounce during mating) they should have relatively thick silver cladding,
because both tin and gold have poor arc behavior—another good reason to
power down before inserting or removing a peripheral card.
Dry circuits have no fault-clearing current flow, and they are susceptible
to electrical noise from imperfect contact. Gold is the preferred dry
circuit contact surface.
--
-michael - NadaNet 3.1 and AppleCrate II: http://michaeljmahon.com
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| Re: Just for some light entertainment [message #374126 is a reply to message #374124] |
Fri, 28 September 2018 03:44 |
Michael J. Mahon
Messages: 1770
Registered: October 2012
Karma: 0
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Senior Member |
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Your Name <YourName@YourISP.com> wrote:
> On 2018-09-28 02:05:55 +0000, James Davis said:
>>
>> I read somewhere, once or twice, that pinching and sliding a piece of
>> typing paper over (down, in the direction of the contacts) on a
>> peripheral card's edge connector was sufficient to clean them. And,
>> that doing something similar in the peripheral card slot,
>
> Best option is to use some rub gently with some cleaning alcohol.
>
> A very gentle rub which some very fine sandpaper can help badly
> corroded contacts, but you have to be extremely careful since rubbing
> too hard will of course just destroy them.
Never sandpaper gold plating. The finest grit will penetrate the very thin
flash playing, and the inevitable residual grit will damage the connector
as well.
If alcohol or water doesn’t do the job, careful work with a pencil eraser
is about as aggressive as I’d be.
Tinned edge fingers are sturdier because the tin layer is thicker, but even
there, sandpaper invites exposing copper to oxidize.
> Another option can be to use small separate strips of aluminium / tin
> foil folded over the card edge where each of the contacts are ... but
> it's not really advisable since the foil can get stuck in the slot when
> you take the card out again!
Not to mention that most edge connectors are double-sided, and you don’t
want to short the two sides together! And aluminum is virtually *always*
covered with a robust oxide layer that will interfere with good contact.
>> and vacuuming them out (with one of those battery operated keyboard
>> vacuums) was sufficient to clean them.
>> 20 years ago, I used a vacuum cleaner once to blow out 20 years of dust
>> from my Apple and my PC. It took me a week to get that dust out of the
>> rest of my house! Should of done it outside. :-)
>
> You aren't meant to use a vacuum cleaner to blow (or suck) dust out of
> electronics. The plastic nozzles can create static electricity, which
> of course can destroy things like the chips in electronic devices.
>
> You also don't blow it out yourself since your mouth will add saliva
> droplets, and of course moisture is also a no-no inside elctronic
> devices.
>
> You're meant to use one of those cans of compressed air, which
> apparently don't create static (somehow, since they too usually have
> plastic nozzles!) nor add moisture.
A good choice for most electronics. Just steer clear of anything with
lubricant or components (like pots) that are susceptible to trapping blown
debris.
--
-michael - NadaNet 3.1 and AppleCrate II: http://michaeljmahon.com
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| Re: Just for some light entertainment [message #374166 is a reply to message #374126] |
Sat, 29 September 2018 14:38 |
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Originally posted by: Oregonian Haruspex
Honestly I have solved a dodgy contact issue by blowing on the connector as
with a Nintendo cartridge on several occasions. I have also used paper with
alcohol, Blast Off, and even vinegar to remove battery corrosion. Problems
like oxidation and plastic degeneration really make me think that
eventually we will all be using “software preservation” aka emulation. I
read about research being done to analyze plastic degradation but it’s
awfully expensive and they haven’t gotten to the part where they halt the
aging process let alone rejuvenate things. I have never used Retrobrite
because I am afraid that it will accelerate the plastic aging process.
Japanese otaku or fan / hobbyist web sites are still the best thing on the
web in my opinion. They rarely need JavaScript and load in a flash. Thanks
for this.
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| Re: Just for some light entertainment [message #374180 is a reply to message #374166] |
Sat, 29 September 2018 21:50 |
Michael J. Mahon
Messages: 1770
Registered: October 2012
Karma: 0
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Senior Member |
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Oregonian Haruspex <no_email@invalid.invalid> wrote:
> Honestly I have solved a dodgy contact issue by blowing on the connector as
> with a Nintendo cartridge on several occasions. I have also used paper with
> alcohol, Blast Off, and even vinegar to remove battery corrosion. Problems
> like oxidation and plastic degeneration really make me think that
> eventually we will all be using “software preservation” aka emulation. I
> read about research being done to analyze plastic degradation but it’s
> awfully expensive and they haven’t gotten to the part where they halt the
> aging process let alone rejuvenate things. I have never used Retrobrite
> because I am afraid that it will accelerate the plastic aging process.
>
> Japanese otaku or fan / hobbyist web sites are still the best thing on the
> web in my opinion. They rarely need JavaScript and load in a flash. Thanks
> for this.
>
Physical degradation of properly stored Apple II’s won’t be our
problem—they should be fine for at least another 50 to 75 years!
--
-michael - NadaNet 3.1 and AppleCrate II: http://michaeljmahon.com
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| Re: Just for some light entertainment [message #374185 is a reply to message #374184] |
Sat, 29 September 2018 22:40 |
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Originally posted by: Anthony Adverse
All this reminded me of a c64 I had for a while... it'd been through a fire, and although intact was quite smoke damaged. In the end we took the mobo out of it, washed it in the bath, and hung it up to dry for a few days, gave it a blow with the hair dryer, and presto away we went.
A
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