Triffid wrote:

>> Thanks for that.
>>
>> I checked and found the disk was already jumped SE. I removed the
>> jumper (what else to try?) but no luck. I tried a few other jumpers,
>> but no improvement.
>>
>> What was odd though is that
>>
>> a) The disk is seen if it is the *only* disk in the machine.
>>
>> b) The disk is seen if it the lower slot (SCSI ID=3), but not if its
>> in the upper one (ID=1). And no, there are not any jumpers installed
>> on any of the SCSI ID select pins.
>>
>> Anyway, it is at least semi-resolved. I've put an operating system on
>> it and it boots OK now. Just needs to be in the lower slot, otherwise
>> it can't be seen on the bus.
>
>
> That's rather odd. There is no physical or logical difference between
> the upper and lower drive bays aside from SCSI ID AFAIK.

Yes, I thought it odd too.

> I suspect your upper bay is b0rked somehow, and won't work with any disk
> as a result.

That is not so.

Here you can see the Compaq disk that presents me trouble in the lower
slot (ID=3) and a Seagate one in the top one (ID=1)


ok probe-scsi
Target 1
Unit 0 Disk SEAGATE ST39103LC 0001LS482885
Copyright (c) 1999 Seagate
All rights reserved
Target 3
Unit 0 Disk COMPAQ HB00931931 03F168224A01GAGSPCQ3F1
09RI9904200012259H7007
E32284 Q59H6952B09E31916 1999
ok


After I swap the disks around, using the same machine, the Compaq one
can no longer be seen.

ok probe-scsi
Target 3
Unit 0 Disk SEAGATE ST39103LC 0001LS482885
Copyright (c) 1999 Seagate
All rights reserved
ok


That behaviour is repeatable.

But when I move the disks to another SS20, both can be seen in any
position, but I'm pretty sure they had the same problem in yet another
SS20.


> I have a couple of spare SS20 backplane & cable assemblies here
> (Toronto, Canada), perhaps you could try one if the logistics aren't too
> complicated.

Thanks, but I am in the UK, so a long way from you, but in any case I
have five SS20's here.

> Triffid


It all seems very odd. But I have had problems with other Compaq disks
in SS20's before, so this is not a total surprise to me.