Bad heads on RL02: Worth replacing

[jim stephens]

On 12/17/2019 8:05 PM, Chris Zach via cctalk wrote:
> Took a look at the top of the RL02 pack. There is a fine layer of 
> white stuff on the disk in a ring at about where I would assume track 
> 0 is on the thing. Wipes off with my finger, but definitely was not 
> there when I put the pack in the drive.
>
> Also, looking at the head under a loupe I can see the head is not 
> perfectly flat when viewed from the side. The front (ahead of the air 
> gap/groove) with the magnetic head is narrower than the back of it. 
> I'm wondering if the head is *worn* to the point where it can't fly, 
> contacts the pack, and what I am seeing on the pack is the ceramic 
> from the head (which would be nice, meaning it's not ripping the pack 
> apart). Then again the black stuff on the head is probably the top 
> layer of oxide from the pack.
>
> Do heads wear out?
>
> C
I don't believe there should be any contact to make any "wear" affect 
the head.  It may have been damaged if you're talking one of the heads 
you cleaned up.  But heads should never really contact the drive on 
these types of heads.

I haven't posted earlier, but I had the same head technology on 
Microdata and Western Dynex drives.  Those had spring steel welded from 
the frame that attaches the positioner and the wires run out to the head 
via that arm.

The thing I had happen was that in fiddling with the head, and cleaning 
it, one could flex the head mounting.  It was a very stiff probably 
stainless steel, but I suspect in cleaning efforts early on when I was 
working with the heads and drives I got hold of some which either I or 
someone prior had over flexed.  The clearance is so small that I think 
that tweek allows the head to look okay, but in actuality isn't flown in 
the proper orientation to stay clear of the media.

I built a number of drives up from highly abused parts, and there were a 
lot of them, so got to play back then and learn.  Huge numbers of media, 
junk drives and the like.

Once I got new heads the problems vanished.  Never did get a reliable 
way to ID a head as good, so I always had a non essential removable 
platter I'd fit the heads to and fly them to see if they caused damage.  
If not, I'd move them to the fixed disk on the bottom of the positioner, 
and mount two more on the top that I'd vetted.  That saved the most 
media and heads.

But unfortunately not good now days where media and heads are scarce, 
since it risks the media and heads.

thanks
Jim