RL02 head replacement, disk back online

[Tom Uban]

It actually looks like the spring on the "wedge" shaped / crashed head has been bent, which would be
a problem...

--tom

On 12/22/19 9:48 AM, Chris Zach via cctalk wrote:
> So after looking at the mess the mice had made of my third RL02 drive I decided it would probably
> be better to pull the heads and put them in my second drive (the one with the bad top head and
> plugged filter).
>
> Getting heads out was simple, and I decided to put them side to side with the heads in drive 2.
> The following images show some interesting details.
>
> https://i.imgur.com/tcmkUmO.jpg
>
> Note that O is original (the heads from drive 2) and the top heads are from drive 3.
>
> First, the heads on the third drive were in pretty good shape and looked clean. Under the loupe
> though I could see some fragments of gunk that needed to be removed. More importantly I did a side
> view comparison between the bad top head in #2 and the top head in #3:
>
> https://i.imgur.com/D6HOxND.jpg
>
> This was a really tough picture to take, and you have to zoom in on the heads in the upper right.
> But what you can clearly see here is that the better head from #3 (left one) is pretty much
> rectangle shaped while the crashing head from #2 (right one) is shaped like a wedge, with the top
> part being narrower than the bottom.
>
> https://i.imgur.com/fEGuOFE.jpg
>
> And of course the filter removed from #2. Note the silicon sludge, I think this is 100% blocked
> (and was why the drive made a lot of air/wind noises when spun up, the fan was cavitating)
>
> This sums it up: I think what happened is the unit was run in a very dirty environment, the
> absolute air filter plugged up, and the heads don't fly as well without that blast of clean air
> coming in. So they dragged on the disk, and the ceramic rubbed off (and onto the packs) which led
> to the eventual disk damage.
>
> Moral: Change filters. I cleaned up the #3 heads, put the heads from #3 into unit #2, put the air
> filter from #3 into #2, and fired it up with the test pack. Goes to ready no problem, will do a
> full dir/bad with RT11 later this afternoon to see if I still have two errors on the pack.
>
> It is interesting to note that the bottom head from drive 2 didn't look too bad, and did not pick
> up any dirt/oxide from the disk after I replaced the filter. It was probably flying very close to
> the platter but had just enough airflow to make it fly. Still, I'll put it in the spares pile and
> think about it for awhile...
>
> Otherwise, back in business. I'll be checking the filter on #1 just to be on the safe side. It was
> my RL02 drive from 30 years ago and was not one of the Solarex ones. Then I'll put fixing this
> third RL02 on the calendar (will need new wiring, long ribbon cable, filter, heads, and a massive
> clean-up inside), and start working on restoring my darn RSX11M 4.2 disk packs...
>