Re: Need help with difficult hd problem: was Gremlins...

alfrede_neumann <alfrede_neumann@xxxxxxxxxx> wrote
> (was "Drive Gremlins continuing saga" I posted a reply to
> "do_not_spam_me@xxxxxxxxxxx" this below twice but it never showed.)

> Further information since last post: I benchmarked the hard drives
> on my system. Drive 0, 20 gb appears to be working normally,
> around 20MB/second both read and write. Drive one, the slave
> for which this machine seems to have destroyed two drives in this
> slot, shows read at 45MB/sec and write at only 2.5 MB/sec (8GB).

What are you measuring that with ?
It may be just an artifact of a poor test.

> Both are WD on primary ide channel. WD diagnostic program
> shows both set to UDMA-66 and OS also set to this, win98SE.
> Both appear to be on an 80 wire cable (from it's looks).

It doesnt take much to count the wires to work
out whether its got roughly 40 or roughly 80.

> The 2.5MB/sec is suspect from the little I know about this
> subject. Re the two drives that seem to have had head
> crashes, killing one and putting a bad spot in the second,

Thats unlikely, real head crashes shouldnt produce that sort of read rate,
particularly if its over the entire drive, not just one patch of the platter.

> does anyone have any further tips in how to diagnose this problem?

I'd check carefully that the write rate is real. Try HDTach.

> Next I will replace the cable with a better round cable, twisted pair.

Dont do that, those flout the standard and the last thing
you need right now is another variable. A new standard
80 wire ribbon cable costs peanuts. Make sure its no
longer than the standard 18" long.

> Maybe this post is overkill since I seem to have generally
> brought two areas of suspicion from the good replies I've
> gotten (much thanks), the power connectors and the power
> in general. Anything else that could show these symptoms?

Its more likely that the write rate is an artifact of a bad test.

> Dell reports that "some" of their models had a problem accepting
> udma-66 settings from the bios, but they do not say which models
> and their "solution" is to reset the bios to auto and reboot. Maybe
> this is a crap MB or bios design?

Its possible. The obvious way to test that is to see how
the 8G drive performs in a completely different system.

> ----
> Subject: Re: Drive Gremlins continuing saga
> From: do_not_spam_me@xxxxxxxxxxx replied:
>
> alfredeneumann wrote:
>
>> Reseated all the power connections, emoried the power
>> connector to make sure the metal contacts were not oxidized.
>
> Don't do that; it can remove the plating and lead to oxidation
> problems
> in the future. Just use alcohol, preferrably 90% or higher purity,
> and plug and unplug the connector several times or wipe the contacts
> with a popsicle stick or toothpick. Allow alcohol to evaporate
> completely
> before reappling power. But more often the problem is loose contacts,
> which can be bent slightly (emphasis) to retighten. Bad contacts,
> crimps, and broken wires can be detected by measuring voltages at the
> circuit board and comparing them to the voltages on unused connectors.
>
> ***
> I actually didn't emory it, I used a micro screwdriver to lightly
> scrap the female connectors. I don't know how you can bend them since
> the are recessed into the plug-how do you do it? Also how can you get
> a vom in there while the comp. is running to test the voltages, seems
> very risky
> to me?
>
>
>> Next step is replacing the cables as soon as I can. There are so many
>> brands out there, it's hard to figure which is the best value; I was
>> unable to find any test data on the 40 vs 80 wires, or anything
>> related to IDE cable testing.
>
> With anything faster than ATA/33, an 80-wire cable is a must for
> reliability, but round cables vary in quality, and many are made
> incorrectly, with straight wires instead of twisted pairs (TPO). The
> safest choice is a $1 generic flat 80-wire cable.
>
> ***
> I was suprised to find it difficult to find any 18 inch flat cable.
> All the ones I saw at egghead were 24 inches and up. Suprisingly, this
> interface must be more robust than I thought, since there are so many
> mfgs. who are selling cables in the 24 inch to 36 inch range. The one
> test I found showed better transfer rates between round twisted pair
> and flat cables, claimning alot of interference comes from outside the
> cable, but this test looked like it could have been sponsored by the
> round cable mfg (no suprise).
> ***


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