Sticking RL02 positioner

[Charles]

-----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 at 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 :)