NetNews Usenet Archive 1992 #18/NN_1992_18.iso/spool/comp/sys/mac/hardware/15657

Text File | 1992-08-20 | 10.2 KB | 196 lines

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Path: sparky!uunet!zaphod.mps.ohio-state.edu!news.acns.nwu.edu!casbah.acns.nwu.edu!golub
From: [e-mail] (Robert Golub)
Subject: Strange flicker on Apple 13" Hi-res monitor (summary)
Message-ID: <[e-mail]>
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Organization: Northwestern University, Evanston Illinois.
Date: Thu, 20 Aug 1992 18:24:07 GMT
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I would like to thank everyone for their responses to my original posting.
Below is a summary of the replies. The consensus appears to be that this
phenomenon can be natural and benign, representing arc'ing of the electron
beam with loose phosphor from shipping; however, frequent occurrences could
cause some monitor damage and may represent a
bad capacitor.
There have been problems noted with specific monitor serial numbers (see
below) and it is possible that Apple would cover cost of repair.
Thanks again!
-Rob
Original posting:
I have a new Apple 13" Hi-Res RGB monitor, and it intermittently does a quick
black jump of the screen image, similar to what happens on-screen during a
restart. It is rare,
and doesn't seem to have any particular pattern to it, and though it may be
associated with closing windows I think it occurs at other times. There may be
a "static" sounding crackle with it. It is *not* at all like the degaussing
effect.
Again, it is rare, and otherwise the monitor seems to be working fine. I have
a new Mac IIci, 8 meg RAM, cache card.
I know that this is somewhat vague, but does it sound familiar to anyone?
___________________________________________
From: [e-mail] (Tom Fussy)
The condition you are experiencing is high voltage arcing internal to the CRT.
It is considered normal unless it is happening frequently (once or twice or
more per day).  Inside the CRT there is a near vacuum.  There are closely
spaced electrodes withing the CRT's electron gun that rely on this vacuum for
insulation.  Small bits
of contamination that are produced during the manufacturing process of the CRT
may
create a path for a spark to jump between electrodes. This is the crackle you
hear.  The screen goes blank momentarily because the CRT's high voltage field
is temporarily nulled.  No need to worry about any of this, unless it is
happening often to the point of annoyance.
If it is happening several times per day, then I would say that you have
reasonable grounds for requesting a replacmement.  How old is the monitor?
This condition often is aggrevated by shipping and handling, but will settle
down after the monitor has been installed over a period of time.
There is no risk to you.
It should die out over time, but may never go to zero instances. The reason I
say you may have grounds to request a replacement
is that there are components mounted on the circuit boards that are designed
to protect sensitive circuitry from the high energy contained in these arcs.
The protecting components have a rated life before they begin to degrade to
where their ability to protect is compromised.  Someday you may have one of
these arcs and your screen may go black
and not come back.  This may require several thousands arcs, but at "several"
per day, they can add up.
I don't know what Apple uses as an accept/reject number for this problem.
Here at Sun
we have monitored this problem using an arc counter on suspected bad units.
We have
been successful at
getting Sony to take back tubes that arc at the 10 per day level. They
consider 1 or 2 per day to be normal, particularly early in the life of the
unit, when floating contaminants are more abundant within the CRT.  If there
is reputed to be a rash of such problems, then it sounds like Sony is having
process problems at their CRT factory.  It still may be worth trying for a
replacement on the chance that you will get a better one.
Tom Fussy
Monitor Development
_________________________________________
From [e-mail] Tue Aug 18 18:11:34 1992
My monitor does a similar thing (don't know if it's exactly
the same) and I believe it's a known bug, from what I read before on the net.
In case no one's posted a response, I'm appending an article I saved from
previous discussions about
this. The article says "shutdown of the monitor" but I interpreted the
discussion at the time to include the bounce/blink that I see.
Btw, I'd definitely call Apple's customer relations number
to check on this program before assuming Apple would pay. A while back,
someone reported that the customer relations people didn't know about the
program, but I'd expect they would by now.
Good luck!
Bill
--------<comp.sys.mac.digest.1199>--------
Subject: Info-Mac Digest V10 #151
>From: [e-mail]
Date: 24 Jun 92 20:03:43 GMT
Info-Mac Digest             Wed, 24 Jun 92       Volume 10 : Issue 151 Today's
Topics: AppleColor High-Res RGB H.V. capacitor (A)
...
Date: Tue, 23 Jun 92 19:12:17 -0700
>From: [e-mail] (Bill Moynihan)
Subject: AppleColor High-Res RGB H.V. capacitor (A)
In an effort to clarify the above subject issue I will give you the Readers
Digest version of Apple's Repair Extension Program 3L0218. 1)The symptom is a
shutdown of the monitor
and the green power-on LED. 2)The monitors were manufactured from March '90
through July 22, 1991. 3)Qualifying capacitors have a date code printed on
their sides
from 0C01 to 1G22 (inclusive). 4)This program will end March 23, 1993. 5)For
those people who have already had their monitors serviced by an Authorized
Apple Service Provider and their monitor serial numbers are 7000001 thru
7101012 or 5378111 thru 5624450 or 9000001 thru 9029500 they are eligible for
reimbursement if they a)have a proof of purchase, b)an Authorized Apple
Transaction Form stating name of service
provider, product serial number, date of repair, parts used in repair, cost of
repair, c)proof of repair payment (canceled check, credit card receipt, paid
invoice). Submit your reimbursement claim to Apple Computer, Inc., Attn. High
Voltage Capacitor
Reimbursement, P.O. Box 17214, Denver, CO 80217.
Bill Moynihan ([e-mail])
__________________________________________
From: Tony Rich <[e-mail]>
Yes, Bill Gibson sent me (and you) the article about bad capacitors.  I had
seen it at the time it came out, but monitors FAILING sounded like a more
serious problem than ours, and our monitor's serial number didn't land in the
range of the serial numbers that were
given (although I see now that its manufacturing date, June 1991, does).  I
didn't pursue the matter then, although I wondered if the problems were
related.
>    If it helps, my serial number is 7101777.
So yours falls (barely) outside their "defectives" range, too -- 7101012 was
the last one they listed in the 7-millions in the "defective capacitors"
article!  Ours is serial number 5017740.  Perhaps you and I are seeing a
"just-starting-to-fail borderline capacitor" problem.
Do you know if anyone who has experienced the jumping has actually gotten
their
monitor fixed (i.e., the problem is gone after taking it in for repair)?
    -- Tony
_________________________________________________
From: [e-mail] (Ralph Paul Ritchey)
Hi.  I'm having the same things that you described happening to my monitor.
THere is an old issue of MacWorld that listed a series of serial numbers for
the Apple monitor that had bad capacitors put in them.  I dropped mine off at
a local apple dealer, and they told me it was fine (right) even though it was
within the range of numbers.  I'm at a loss as to what's going on with it,
since it does it so infrequently.  If you hear anything, could you let me know
about it?  Thanks.
Ralph Ritchey
[e-mail]
______________________________________
From: [e-mail] (Philip Heacock)
I have talked to three people who have bought 13 inch monitors in the last six
mo. All of them exhibit this behavior.  The "problem" (is it?) is independent
of cpu.
-Phil
________________________________________
From: [e-mail] (l boyd)
Make that four!   My 1-month-old monitor went (quite literally) on the blink.
Of course, now I can't reproduce the problem, but I DO HAVE A WITNESS!
I do believe the problem is independent of the CPU -- it might even be
something
as "stupid" as a loose cable, though that was the first thing I checked.
Lauren Boyd                                     Department of Otolaryngology
Systems Analyst/Programmer                      University of Washington, RL-
30 *Go Huskies*                                    Seattle, Washington  98195
________________________________________
From [e-mail] Wed Aug 12 10:20:47 1992
I've had that happen on all of the Apple 13" RGB monitors I've ever had, plus
I just saw it on one of the new 16" color monitors.
I have been told that this is normal on new trinitron tubes. The crackle you
hear is the electron beam arc'ing inside the tube as loose phosphors from the
tube manufacture float around inside the tube.
I do not know if this is true or not, but it makes sense, and the 'crackle'
has always gone away after a while.
Mike Shoemaker
Apple Computer, Inc.
______________________________________________
From: [e-mail] (john r park)
It sounds like you have a bad High Voltage Capacitor.  This is a known problem
in the
13" monitor.  Most apple dealers will fix this for free if it falls within a
certain range of serial numbers.
John R Park                |  Dept of Mech. Engineering [e-mail]
|  Brigham Young University
_____________________________________________
From: Gerard Hammond <[e-mail]>
I've had exactly the same problems. the screen just does a quick
flick and then it's ok. Happens very intermitently and
usually  happens after a mouse click. I too have a IIci, Cache card
8       megs ram. Sounds suspious doesn't it?!
Please Keep me informed!
best regards
Gerard Hammond
Dept Chem
Univ of New England
Armidale
Australia
--
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Robert M. Golub, M.D.           Division of General Internal Medicine
222 E. Superior                 Northwestern University Medical School
Chicago, IL 60611               E-mail: [e-mail]    Voice: [phone]