That would be test 24. Values are recomputed by creating a gains tape by
writing to the loaded scratch tape. Pressing the rewind button, press the
reset button. And then press the button... acceptable values for average
gain is E0 to 60 hex... all of this based on my memory from many moons ago.
CLEAN THAT HEAD ALL THE to the BACK! -an old salty HP CE taught me that one
years ago.....!!
Ryan C. Melander
Ideal Computer Services, Inc.
88 Wright Brothers Ave.
Livermore, CA 94551
Ph. 800-862-8787
Ph. 925-447-4747 x213
Fx. 925-447-4780
[log in to unmask]
-----Original Message-----
From: HP-3000 Systems Discussion [mailto:[log in to unmask]] On Behalf
Of John Pitman
Sent: Tuesday, July 20, 2010 3:22 PM
To: [log in to unmask]
Subject: Re: [HP3000-L] Old HP
Be aware that adjusting or recalibrating heads can render ALL tapes made on
that drive in recent times unreadable......
Regards,
John Pitman
-----Original Message-----
From: HP-3000 Systems Discussion [mailto:[log in to unmask]] On Behalf
Of Brett Forsyth
Sent: Wednesday, 21 July 2010 12:46 AM
To: [log in to unmask]
Subject: Re: [HP3000-L] Old HP
Jim,
My memory is a little foggy, but I believe there is an automatic head
alignment routine onboard the 7978 - accessable via the front panel - it
sets
the amplitude and adjusts for head skew electronically - things that get out
of
whack as a head wears down. I'm pretty sure we did this as a common
procedure back in the old days. You may not need a new head (yet) - it
might just need recalibration.
The head actually gets "louder" as it wears down and you get closer to
the
electronic pickups, and an over amplitude problem was common, thus the
onboard alignment diag. Same thing with skew - although minute, the pickups
are never perfectly straight and as you wear the head down this becomes an
issue.
I popped this out to the list as well because I don't know the access
codes/key panel strokes any more, but perhaps someone listening may not
have destroyed as many brain cells in the last few years and might be able
to
walk you through it.
Good luck,
Brett J Forsyth
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