5 Feb
2004
5 Feb
'04
3:56 p.m.
I have gotten a few pairs of RL02 head assemblies, and I'd like to know
if they are used in 'pairs' per se, or if the upper and lowers are
interchangable, or does any of this matter...?
I know there are a few folks on the List experienced in changing out
head assys on the large-format drives, so I thought I'd ask.
BTW: I'm keeping a couple of pairs, and the remaining sets have already
been spoken for (all by Listmembers) so regretfully I have no extras at
this time. ;{}
Cheers
John
5 Feb
5 Feb
4:07 p.m.
I have gotten a few pairs of RL02 head assemblies, and I'd like to know
if they are used in 'pairs' per se, or if the upper and lowers are
interchangable, or does any of this matter...?
The upper ('down'[1]) and lower ('up') heads are different (they're
almost
mirror images of each other, so that the cable comes out on the same side
when installed).
However, they're not always fitted in pairs -- often you just replace the
bad head. I've never actually done an RL head replacement, but I've done
it for RK05s, and I remember just replacing a single head if the other
one was OK. The heads do not come as matched pairs, any 'down' head will
work with any 'up' head.
Note that RL01 and RL02 hheads are different, and you can't use the
'wrong' ones in either drive (you get something similar to the 40/80
cylinder problems on 5.25" floppies if you try)
[1] It's conventional to refer to these heads by the direction they face
when installed.
-tony
6 Feb
6 Feb
3:53 a.m.
On Thu, 5 Feb 2004, Tony Duell wrote:
bad head. I've never actually done an RL head
replacement, but I've done
it for RK05s, and I remember just replacing a single head if the other
one was OK. The heads do not come as matched pairs, any 'down' head will
work with any 'up' head.
There are definitely different kind of RK05 heads. We had to replace the
heads from a RK05 drive for our LAB8/e just two or three weesk ago. Trying
to align the heads with an alignment pack and executing the data
reliability tests revealed that there are low amplitude heads and high
amplitude heads as well as low amplitude disk packs and high amplitude
ones. The failed head was a high amplitude one and we tried several
low amplitude heads that wouldn't work together with the read/write
amplifier card. At last we found a head pair with high output.
Afterwards we found a small note in one ECO manual for the RK05 that
mentioned high and low amplitude packs but not heads. Our scope (btw. a
very good Tek 555!) proved that there are different heads, too.
Christian
8:43 a.m.
>>>> "Christian" == Christian
Corti <Christian.Corti(a)studserv.uni-stuttgart.de> writes:
Christian> On Thu, 5 Feb 2004, Tony Duell wrote:
> bad head. I've never actually done an RL head
replacement, but
> I've done it for RK05s, and I remember just replacing a single
> head if the other one was OK. The heads do not come as matched
> pairs, any 'down' head will work with any 'up' head.
Christian> There are definitely different kind of RK05 heads. We had
Christian> to replace the heads from a RK05 drive for our LAB8/e just
Christian> two or three weesk ago. Trying to align the heads with an
Christian> alignment pack and executing the data reliability tests
Christian> revealed that there are low amplitude heads and high
Christian> amplitude heads as well as low amplitude disk packs and
Christian> high amplitude ones. The failed head was a high amplitude
Christian> one and we tried several low amplitude heads that wouldn't
Christian> work together with the read/write amplifier card. At last
Christian> we found a head pair with high output. Afterwards we
Christian> found a small note in one ECO manual for the RK05 that
Christian> mentioned high and low amplitude packs but not heads. Our
Christian> scope (btw. a very good Tek 555!) proved that there are
Christian> different heads, too.
That's puzzling.
On the other hand, I remember a difference between "up" and "down"
heads, which has to do with the way the heads "fly" above the disk
surface.
The heads need the right amount of pressure towards the disk surface
for the flying height to be correct. If it isn't, you'll get low
amplitude (flying too high) or possibly head crashes (flying too low).
For a head flying above the disk, gravity and the head mounting
springs are pushing in the same direction; for a head flying below the
disk, gravity is lifting the head away from the surface while the
mounting springs push it to the surface.
So I would expect a head meant to be above the disk to give low
amplitude if installed below the disk. In any case, this is one
explanation why it matters.
paul
7640
days inactive
7641
days old
3 comments
4 participants
participants (4)
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ard＠p850ug1.demon.co.uk -
Christian.Corti＠studserv.uni-stuttgart.de -
jpl15＠panix.com -
pkoning＠equallogic.com