Sticking RL02 positioner

[Paul Koning]

> 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