-----Original Message-----
From: Paul Koning
Sent: Monday, April 08, 2019 6:26 PM
To: Charles ; General Discussion: On-Topic and Off-Topic Posts
Subject: Re: Sticking RL02 positioner
On Apr 8, 2019, at 6:11 PM, Charles via cctalk <cctalk@classiccmp.org>
wrote:
One of my RL02 drives (that sat for a long time) has developed what
appears to be a sticky head positioner.
But it's only a problem going from the full-retracted position to loading
track 0.
Once it's loaded, the drive will pass all seek and read/write tests.
It takes a surprising (to me) amount of force to pull the heads out into
the disk area (power off, no pack). When they're out there, the arm slides
back and forth easily.
Sometimes it won't load at all - push the load button, light goes out,
disk spins up to what sounds like normal speed, but the heads never move
and the Ready light doesn't come on.
There's supposed to be a Fault after 40 secs but that doesn't happen -
it'll sit there forever spinning but not ready.
If I turn off the power and remove the pack, and pull the positioner out
just enough to avoid opening the Heads Home microswitch (which causes a
Fault light), then it'll spin up, load track 0, and work fine the rest of
the day.
The manual (as usual) only recommends replacing the bad assembly for ease
in field servicing, which is deliberate.
But I don't have a DEC repairman and a warehouse full of parts handy... Is
there some kind of adjustment or lubrication I can do?
Lubrication in a disk assembly sounds like a thing to avoid because of
contamination.
I don't know the RL02 specifically, but some pack type disk drives have a
"head unload ramp", a wedge shaped device that lifts the heads away from the
platters when the positioner retracts to the unload position. I wonder if
there might be dirt on those that could be cleaned with a suitable cleaner
(kimwipes or similar lint free cleaner) and solvent (96% isopropanol comes
to mind). Does the book give any guidance about this sort of thing?
paul
===============================================
Yes, I am sure there is such a ramp, since the heads do move close together
when the positioner extends. I can feel it "wedging".
I'll take another look at it, when I have obtained some lint-free wipes or
swabs :)
