[Soekris] problem with net4801 and 2.5 hdd

[RW]

On Mon, 20 Aug 2007 02:11:02 -0700, Jingshao Chen wrote:

>On Fri, Aug 10, 2007 at 08:58:12PM +1000, RW wrote:
>> On Fri, 10 Aug 2007 09:46:00 +0200, Eduardo Diaz Comellas wrote:
>> 
>> >Hi all,
>> >
>> >I am facing a problem with some net4801 units and a 2.5 HDD. The disk 
>> >works fine in one of the soekris boxes I've got, but on others it hangs. 
>> >The boot log of a faulty reboot is:
>> >
>> >comBIOS ver. 1.31  20070408  Copyright (C) 2000-2007 Soekris Engineering.
>> >
>> >net4801
>> >
>> >0128 Mbyte Memory                        CPU Geode SC1100 267 Mhz
>> >
>> >Pri Mas  ST940<1=A                       LBA Xlt 1024-255-63  39070 Mbyte
>> What does ^^^^^^^^^  say when the drive is in a "good" unit ?
>> 
>
>In his original email, down it said " ST940815A"...
>
>
>> I <think> I know what the problem is but I need the other info to be a
>> bit more confident.


Ok. In every case where the characters in that string differ the diff
is in the upper two bits of the lower nibble. i.e. bits 2 and 3 of the
8 bit char field.

Those two bits are the same for S 0 1 and A and those chars are never
in error.

Let's deal with t'others:
 8 turned into <  means that bit 3 was high and bit 2 was falsely high.
 5 turned into = means that bit 2 was high and bit 3 was falsely high.
There are anomalies:
4 was correct (2 high 3 low)
9 was correct (3 high, 2 low)

My theory is that bits 2 and 3 have a (at least partial) short circuit.

Sometimes it shows up and sometimes it doesn't.

Commonly zeros trump ones but it is a battle between two voltages and
the threshold of the next gate in the circuit.

I'd be looking for a flaky IDE cable (most likely) or some "tracking"
on the PCB at either end(much less likely. ISTR it was the same drive
both times so that leaves the Soekris PCB and I think that QC at
Soekris is way too good for that.)

Check the cable for insulation between data bits 2 and 3. I don't have
a pinout to hand but you'll find one if you ask Mama Google,

Good luck!

Rod/
>From the land "down under": Australia.
Do we look <umop apisdn> from up over?