Bad heads on RL02: Worth replacing

[Chris Zach]

Pulled the air filter on this unit. Completely plugged with brown/black 
junk, I can't believe much air was going through. So it's possible that 
the heads were in a partial vacuum and couldn't fly?

Off to find a fresh RL02 filter from Amazon. :-)

C

On 12/18/2019 9:37 AM, Chris Zach via cctalk wrote:
>> 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.
> 
> Thanks Jim: The problem was happening before I removed the head, and the 
> symptoms (ring of white dust on the disk) has been going on for awhile 
> so I don't think it was the cleaning that threw it out of alignment.
> 
> I took a set of watch calipers to the head this morning to see if I 
> could measure the head width front to back (where front is the part of 
> the head closest to the spindle and back is the part of the head 
> furthest). Without removing the head from the head arm it's tricky to 
> measure, but it's pretty clear that the ceramic on the rear of the head 
> is thicker than the ceramic on the front of the head.
> 
> Which would make sense if it was dragging, as the ceramic would be worn 
> down by the pressure of the arm spring pushing down more on the front 
> than back. Once the head is angled it probably will not fly.
> 
> The next question and the really fun one is if the magnetic bar and 
> loops that are embedded in the ceramic are above the level of the 
> ceramic head. Ceramic on disk would leave wear, but I'll bet that steel 
> of the magnet would carve a nice trench.
> 
> I'll try to take a picture this evening but in the meantime unless 
> someone says that a wedge shaped head is "normal" I'm flagging this one 
> as bad.
> 
> Thank you for the write-up below. Amazing stuff...
> 
> C
> 
>>
>> 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