Re: HP7933 - Was: newbie question -storing a file from tape to disk -

The head cable connectors were color-coded depending on the drive they
were manufactured for...either 793X or 792X. I don't recall which was
which, but there were green connectors and yellow connectors on the new
heads. I think the green ones were for the 792X drives and the yellow
ones were for the 793X drives, but it could be the other way.

Something else you may have run into, was the 7933 head assembly getting
stuck to the "crash stop". If the drive thought the heads might be
about to crash, such as during a power failure, the actuator would do an
emergency retract to get the heads off of the platters to prevent a
crash. The actuator would retract the heads really fast and the head
assembly would come to a rest when it hit a foam pad called the "crash
stop". With age, the foam pad started to deteriorate and became sticky
(like the foam sound abatement for a 256X printer). When a 7933 with a
sticky crash stop experienced a power failure, the actuator assembly
would retract back fast and get stuck to the foam. When power came back
on, the heads wouldn't load because they were still stuck to the crash
stop. A quick flick of your finger was all it took to get the heads
rolling on their rails again. What was HP's solution to fix this?


Answer: apply talcum powder to the foam pad, being sure to dust it off
good to minimize the amount of powder that could find its way into the
disk chamber.

Then there's the time I pull-started a 7933 spindle motor using one of
my shoe strings, like pull starting a lawn mower. The 7933s ran for a
long time and the ball bearings in the motor heated up. When powered
down for a PM, they cooled. Sometimes when trying to spin them back up,
they wouldn't get up to speed quick enough during the self test so the
self test would fail, not allowing the drive to be used. I removed my
shoe string, wrapped it around the large nut on the bottom of the disk
pack spindle motor, turned on the drive and pulled as hard as I could to
help the motor get up to speed. It worked. Spindle motors didn't fail
that often, so we didn't stock one in our HP office. Once the drive was
up to speed and passed its self test, the drive could be used for a few
days while I ordered a spindle motor to replace the defective one.


Regards,

Steve Gray
Abtech Support



-----Original Message-----
From: HP-3000 Systems Discussion [mailto:HP3000-L@xxxxxxxxxxxxx] On
Behalf Of Denys Beauchemin
Sent: Thursday, March 06, 2008 9:26 PM
To: HP3000-L@xxxxxxxxxxxxx
Subject: Re: [HP3000-L] HP7933 - Was: newbie question -storing a file
from tape to disk -

I believe you are correct. They had to color-code them. I remember the
jockeying for position to get these heads, what a screw-up that was.

Does anyone remember when HP got out of the disk drive business? I
think it was around 1995.

Denys...

-----Original Message-----
From: HP-3000 Systems Discussion [mailto:HP3000-L@xxxxxxxxxxxxx] On
Behalf Of Joseph Dolliver
Sent: Thursday, March 06, 2008 5:14 PM
To: HP3000-L@xxxxxxxxxxxxx
Subject: Re: [HP3000-L] HP7933 - Was: newbie question -storing a file
from tape to disk -

Yeah, they were called green heads as I think.

Huge fail rate, kept HP busy for months replacing them all

From: Gary Robillard <gary.robillard@xxxxxxxxxxx>
Date: 2008/03/06 Thu PM 03:10:42 CST
To: HP3000-L@xxxxxxxxxxxxx
Subject: Re: [HP3000-L] HP7933 - Was: newbie question -storing a file
from tape to disk -

Since the 7933/35 topic seems to live on...

The head problem didn't cause disk crashes, but was a problem where the

head cables would become intermittent and finally would lose their
connection, causing read/write problems (if you were writing when the
cable quit, you now had bad data on your disk). That is what prompted
the badsectr utility which was originally written for MPE/V.

The 7933 was released because they couldn't get the seal right in order

to prevent contamination from entering the disk pack when it was
changed, so the door unlock was defeated and it was a 'fixed' pack.
Once the seal problem was fixed, the 7935 was released with the 'door
open' switch operable...

Thanks,

Gary Robillard



-----Original Message-----
From: HP-3000 Systems Discussion [mailto:HP3000-L@xxxxxxxxxxxxx] On
Behalf Of Gilles Schipper
Sent: Thursday, March 06, 2008 11:36 AM
To: HP3000-L@xxxxxxxxxxxxx
Subject: Re: [HP3000-L] HP7933 - Was: newbie question -storing a file
from tape to disk -

If my memory serves me correctly, some time after the 7933 was
announced and became quite popular, HP had a massive "recall" in order
to change faulty heads that were causing disk crashes.

This required CE's to replace the heads on any affected 7933 at the
next opportunuity - usually the next preventative maintenance call.

Now here is where my memory may be a bit fuzzier, but I seem to recall
that around that time, HP announced the 7935, which was exactly the
same as the 7933, but was modified to permit the user to replace the
diskpack itself.

(Perhaps the 7935 was the original and the 7933 was the one with
user-replaceble disk packs.)

-----------------------------------------------------------------------
-
Gilles Schipper
GSA Inc.
HP System Administration Specialists
300 John Street, Box 87651 Thornhill, ON Canada L3T 7R4
Voice: 905.889.3000 Fax: 905.889.3001
email: gilles@xxxxxxxxxx web: http://www.gsainc.com
-----------------------------------------------------------------------
-

---------- Original Message -----------
From: "Bob J." <BobJ@xxxxxxxxxxxx>
To: HP3000-L@xxxxxxxxxxxxx
Sent: Thu, 6 Mar 2008 13:20:14 -0500
Subject: Re: [HP3000-L] HP7933 - Was: newbie question -storing a file
from tape to disk -

As we travel down memory lane............
CEs were supplied a hoist to attempt installing & servicing the upper
7933 drives.
That setup never seemed safe for anybody within 20 feet of the racked

drives.
Sleuth was fun for the Series II/III. SleuthSM (simulator) was nice
for
the
HP-IB systems. Those utilities that did the actuator "butterfly" test

would usually pass through the resonant frequency of the drive to
make some scary noises.

Bob J. -- Ideal Computer Services
http://www.icsgroup.net

Jeff Kell wrote:




Does anyone recall the "rack-mounts" for stacking 7933s? Anyone
else ever "race" 7933s across the DP centre floor by judicious use

of adager or fcopy?


'Sleuth' on a 7920/7925 could produce some very humorous results.
Don't recall that utility making it beyond the Series II/IIIs
though.

Jeff

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------- End of Original Message -------



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joseph dolliver
e3k solutions , inc
41630 marie court
leonardtown, md 20650
301-475-6985

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