6 May
1999
6 May
'99
2:57 a.m.
-----Original Message-----
From: Tony Duell [mailto:ard@p850ug1.demon.co.uk]
Sent: Wednesday, May 05, 1999 12:01 PM
To: classiccmp(a)u.washington.edu
Subject: Re: Dec RL01 drive problem
The speed behaviour might be correct. The speed of the spindle motor in
an RL01 is regulated, and the feedback is taken from the sector
transducer. Without a pack in place, there will be no sector pulses, so
no feedback, so the logic will think the motor is stopped and will try to
speed it up.
If the heads are attempting to load, then the drive thinks the pack is
spinning at the right speed.
The spindle motor speed being regulated explains why things slow down. They
just slow
a little too much. The motor can't be doing any more than 120 RPM when the
heads attempt
to load.
My first thought is that for some reason the heads are not detecting the
servo pattern on the disk, so they can't lock to it. I assume you're
using a known-good RL01 pack -- and not just some pack that looks right,
an RL02 pack, or one that has been bulk-erased.
Well the answer is yes and no. I just purchased two DEC brand RL01 packs
from
Keyways. They came "as-is" since Mitch didn't have a drive to test them on.
Both packs
behave the same.
Are the heads clean and correctly connected to the R/W module (central
module in the drive chassis)?
Heads look clean and all connectors within the drive look firmly seated. The
head assembly
moves freely.
If yes to both of those, then we need to troubleshoot the servo logic. I
have the printset and tech manual here. You'll need a 'scope, though.
I'm sure I can find one in a couple of days. Is there anything else that
should be checked
first (power supply)?
-tony