Help fixing a broken RL02

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Tue Jan 13 15:17:17 2004

>
> All,
>
> I'm looking for any hints or advice on repairing a broken RL02
> drive. I have two drives, one is working, the other indicates a fault.
>
> The unit with the fault lights the fault light as soon as it's
> powered up, it goes through it's normal power up cycle (runs the spindle
> at low speed) and seems normal beyond the fault.
>
> All power supply voltages are normal.

'All' meaning the +/- 8V rails and the +5V rail I assume.

>
> I've swapped the 'easy' to swap parts with my working unit however
> the fault persists (swapped the logic board that lives on the top/back
> cover, the servo board and the unit select buttons). Before I tear

It could be a fault on just about any part of the drive. For example, the
R/W module will cause a fault if it detects a current in the head (i.e.
the drive is writing) without write_gate being asserted.
 
> deeper into it I was hoping someone might have some hints or experience
> that will help me.

Stop swapping boards! That's no way to fix a computer (any computer, but
particularly a classic one).

Do you have the printset (schemciatics)? If so, look at the fault logic
on the drive select board. You'll see it's basically a logical OR gate
that combines about a dozen signals. First check that the output of that
gate is asserted (just in case the fault lamp driver has shorted or
something, although as you swapped ou the logic board this is unlikely!),
then see which of the inputs is asserted. Trace back from there to find
out _why_.

At least the RL02 can be worked on without extended boards...

-tony
Received on Tue Jan 13 2004 - 15:17:17 GMT