26 Feb
2003
26 Feb
'03
1:13 p.m.
From: ard(a)p850ug1.demon.co.uk (Tony Duell)
Try re-seating the 'ribbon cable' between the CPU
board and the disk controller PCB _at both ends_. I
would estimate that over 50% or disk problems on
M3s and M4s come from this cable!
You're right about this. It all starts to come back to
me... *Grin!*
This was one of the first things I'd do when a machine
came in with disk controller problems.
I'd also remove the cable totally and clean the
connections with a pencil eraser and possibly some
alcohol.
Mostly, I'd just use the eraser.
Tin to Tin connections would often get oxidation.
Jerry Pournelle used to talk about something called
Stabilant-21 that worked well to keep this from
happening.
This stuff worked great on Model I keyboard to E/I
cables (I soldered on the infamous Gold Plugs on mine.
and made a gold and shielded cable besides) and floppy
cables.
But since the behavior changes when he moves the
drives, it sounds like his "0:" drive is bad.
Regards,
Al Hartman
27 Feb
27 Feb
10:21 a.m.
From:
ard(a)p850ug1.demon.co.uk (Tony Duell)
Try re-seating the 'ribbon cable' between the CPU
board and the disk controller PCB _at both ends_. I
would estimate that over 50% or disk problems on
M3s and M4s come from this cable!
You're right about this. It all starts to come back to
me... *Grin!*
This was one of the first things I'd do when a machine
came in with disk controller problems.
I'd also remove the cable totally and clean the
connections with a pencil eraser and possibly some
alcohol. But since the behavior changes when he moves the
drives, it sounds like his "0:" drive is bad.
I rather gave up when he started swapping parts round!. I prefer to start
with a configuration that I know was capable of working...
As you said there are possible drive select and termination issues. So
I'd want to keep the drives as they were originally, at least for the
moment. And I would then start troubleshooting drive 0.
In particular, does it do anything when the machine is powered up/reset
with a disk in that drive. Does the motor even spin? If not, then I would
grab the logic probe and meter and start tracing signals. If you want to
do this, I have the schematics, etc to hand, and can talk you through it.
-tony
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