Well, I did check the head pretty thoroughly before installing it: One problem was there were dirt particles that were not coming off so I used the tip of a tweezer to loosen them up. Note I do this to watch dial faces from the 1870's (oddly enough also porcelain) so I'm pretty careful and am not making major scratches into that ceramic head. But I did a finger check, it's smooth. I'm wondering if the problem is the leading edge of the head is angled down or something: From the debris on the leading edge it's looking like it is digging into the pack. Not sure if this can be adjusted, or even what adjusting the head would be like. Interesting. I'll check the pack next weekend for damage before trying it in the good RL02 to see if it has any more errors on the disk. C On 12/16/2019 7:23 PM, dwight via cctalk wrote: > The head likely has something on it that you missed. Use your finger > to feel the head. Your finger is quite sensitive to tiny roughness. Of > course, clean your finger oil off before putting it back in. Make sure > that first landing area is smooth and flat. Almost all of the head > needs to have the cushion of air. With things stationary, look at how > the head comes down on the surface. The larger part needs to be > parallel to the surface. Most heads have a slight curve on the leading > edge to help trap the air. > Dwight > > ________________________________ > From: cctalk <cctalk-bounces at classiccmp.org> on behalf of Chris Zach > via cctalk <cctalk at classiccmp.org> > Sent: Monday, December 16, 2019 3:07 PM > To: CCTalk mailing list <cctalk at classiccmp.org> > Subject: Bad heads on RL02: Worth replacing > > So one of my RL02 drives (bought on Ebay years ago) is eating RL02 > packs. Makes tings, then the disks have errors in my other RL02 drive. > Took a bit to figure out which drive was eating what, but I'm 100% > certain it's this newer drive. > > So pulled the heads. The top one had significant gunk on it, the bottom > one a bit. Pics below. > > Top: https://i.imgur.com/FELhF9X.jpg > Bottom: https://i.imgur.com/Tmsf5Nd.jpg > > With alcohol and lintless swabs I managed to clean both of the heads up. > > Top: https://i.imgur.com/gmACM4R.jpg > Bottom: https://i.imgur.com/SfZQV5F.jpg > > Then put them back in the drive and mounted a scratch pack. With finger > on the load/run I let the drive spin up and when I heard tinging I > immediately spun down. Hopefully I didn't trash my scratch pack. > > Top head has gunk, bottom one had a few flecks, but looks pretty ok. > Top: https://i.imgur.com/EAvgmuH.jpg > Bottom: (picture didn't upload) > > Obviously the head is crashing, any idea why and if it's worth replacing > the head or should I put this drive out for parts? Yes I cleaned the > RL02 pack before putting it in. > > Never dull. > CZ >

On 12/16/19 7:57 PM, Chris Zach via cctalk wrote: The characteristics of the head are not adjustable. In my experience with 2315 packs, the top heads are the most prone to crashing. You have to make sure the platter is absolutely clean, spinning at the right speed, and there is nothing on the outer edge when the heads load.

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

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