"Paul" schreef in bericht
...
Rod Speed wrote:


"R. C. White" wrote in message
...
Hi, Mark.

I took off the cable at both ends and reconnected it.

Ah, yes, the old "Pink Pearl" treatment. ;)

Shades of the TRS-80! ;^{

Way back in 1978, when we had unexplained glitches, we would unplug
cables - usually from edge-cards in those days. Then we would give the
edge card connectors the "Pink Pearl" treatment: we would "erase" the
film of fine debris from the edge-card teeth using a pencil eraser, with
Pink Pearl being the most common brand name for such erasers. Then we
would plug the connector back onto the edge card and...problem solved.
;) Often we didn't even need the eraser; just unplug the cable and
plug it in again, letting simple friction remove the film. That simple
solution still works surprisingly often. ;)

It shouldn't be happening with modern standardised cables.


As I understand it, this is a connector retention problem
or a kinked cable problem.

First generation cables have absolutely nothing to hold them in
place. The connector body didn't provide a compression (interference)
fit. SATA cables would regularly fall off, due to vibration.

This happened, because the dudes at SATAIO were spending all their
time designing the perfect "SATA backplane connectors". That allows
disk drives to be plugged into slots in a server. Such as the 24 bay
"things" you can get for servers, to hold drives. Those have a
SATA backplane in back, and the carefully designed SATA connectors
are inside the box.

For the desktop, they just decided to "saw that connector in half
and send the plans to China". Without even checking whether this
was a good fit for desktop systems or not.

Later, some of the little people in the industry decided to
fix this stuff. So the connector body got deformed a bit,
to provide a compression fit. And later, the "metal jaw" thing
was added. The metal jaw thing has to be designed, so if the
mating member isn't available on the other end, the parts don't
conflict.

I got a new motherboard with jaw-equipped cable, and it would not
fit on my WD branded hard drive. So I had to fall back to the
simpler cable (deformed body). Thus, there are at least two retention
features available, and sometimes both features are on the same
connector. And this is all because the SATAIO committee didn't
test their original design before shipping it. (Otherwise, they
would have noticed how bad it was.)

The contacts are gold on gold, which relies on a "wiping" action
rather than the "biting" action of tin on tin. Since the gold is so thin,
erasers are no longer recommended for "reconditioning" the contacts.
The gold is so thin (10u instead of 50u), there might already be
pinholes in the finish. If you must clean such a connector, try
isopropyl alcohol and a lint-free cloth. I would not recommend
anything stronger than that.


Is that what's sold as 'contact cleaner'?



The SATA cable should not be bent until it kinks. This has an impact
on the dielectric insulation inside the cable. And can change the
cable impedance. It's more likely to be a problem, if one conductor
is kinked and the other one is not. When the cable changes direction,
try to make a "rounded corner" in the cable, not a pinch. I'm still
waiting to see an eye diagram or a TDR picture of a kinked cable,
to see just how bad bending them is.

And use some care when disconnecting a cable from a motherboard.
There was one brand of motherboard, with vertical connectors, where
the manufacturer didn't affix the connector body to the board very
well. A user would tug on the cable, and pull the connector
right out of the motherboard. Later connectors were fastened a bit
more securely than that.



thanks for your historical overview.
As I wrote, the MB and cable aren't exactly new. Do you have links to
pictures of the connector types you mentioned above? I understand they are
not exactly compatible?
For the moment this computer boots OK, but I'm still thinking about getting
a new cable and I don't want to buy the wrong type.
The MB is SATA II, and I believe nowadays the standard is SATA III, if that
makes any phisical difference.
BTW I never pull at the cables, I always pull the connector itself.
There are no sharp bends in the cable, but I suppose that's no guarantee
that there isn't any invisible micro crack somwhere in the cable.



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