RK05 head alignment -- how difficult?

Guy Sotomayor Jr ggs at shiresoft.com
Mon Jul 24 10:39:31 CDT 2017


> On Jul 23, 2017, at 10:12 PM, Fritz Mueller via cctalk <cctalk at classiccmp.org> wrote:
> 
> Hey folks:
> 
> As some of you know, I've recently restored a PDP-11/45, RK11-C drive controller, and an RK05 drive.  I'm now at the point where I'm working to recover and archive the contents of the dozen or so RK05 packs that I got along with the drive and controller.
> 
> I've been inspecting and cleaning packs as I go, and have avoided mounting any packs that have signs of significant crashes (e.g. full rings down to the shiny aluminum) or any that have corrosion "pox".
> 
> Other packs have had just little "black smudge" style head crashes that come off with some determination with kimwipes and alcohol.  I've had pretty good luck recovering data from these.  Occasionally the drive will make a sort of "deli slicer" sound -- I run and unload the pack, disassemble it, clean any new smudges, open up the drive, give the heads a good inspection and clean, and continue on.  It's a little painstaking...
> 
> As I've gone through this process over a number of weeks the heads are accumulating dust and oxide in places that are hard see and get to, and I feel like I'll soon need to pull them and take them to my bench to really give them a proper and thorough inspection and cleaning.  I guess I'm looking for some advice/calibration from the community here.  Is it:
> 
>  "OMG, are you nuts, don't take the heads out, you'll never get them aligned,"
> 
> or is it:
> 
>  "Meh, RK05 alignment is not really that tough, and you would be better off making sure your heads are thoroughly clean and intact."
> 
> Any advice appreciated!

It’s not terribly difficult to align the heads on an RK05 drive.  The issue is if you want pack interoperability.  Unless you know that you have packs that were written with a drive that was in good alignment, you’ll need an alignment pack.  Alignment packs are easy to identify in that they’re red in color.

However, since you’re probably just dealing with you’re own collection of packs, it’s probably sufficient to use one to do the initial alignment and then check it with a couple of others.  Basically what you’re looking for is to have the heads be in the nominal center of the track.  There is some tolerance but if too far out can result in interchange issues with other drives (e.g. one’s too far “out” and the other is too far “in” and results in not being able to read tracks written on one drive with another).

As I recall the description on how to align the RK05 drive is in some of the DEC docs (I’d have to dig them out to determine which one).

TTFN - Guy




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