khayo@sonia.cs.ucla.edu (Erazm J. Behr) (01/13/88)
This was noticed (and discussed, with no concrete conclusions
as far as I remember) a half-year ago or so. The SE in our
department also has this problem, but it's hardly noticeable.
A conjecture/question: is it possible that the power supply
transformer (stronger in the SE, but just as close to the CRT
as in the Plus - which doesn't suffer from the problem) is
generating an alternating magnetic field powerful enough to
escape the (insufficient?) screening and deflects the beam
in the tube? Topologically, it would make sense. Eric.
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>>>>---------------> khayo@MATH.ucla.edu long@viking.dec.com (Rich Long - LJ02 - DTN 226-2598) (01/13/88)
Hello everyone,
This is my first USENET posting, so please forgive me if I do anything wrong!
I'm having a problem with my Macintosh SE that I hope has a cure: It has had a
screen jitter almost since the day I bought it.
System Configuration:
Apple Macintosh SE
2.5 MB RAM (Apple Upgrade, done with analog board replacement, see
below)
Internal HD20
Internal 800K floppy
Extended Keyboard
The machine was purchased in August of 1987, and the jitter grew steadily
worse, until the analog board was replaced under extended warranty in December
1987. That fixed the problem for a short time, but it has recurred, and seems
to be getting worse again! The whole screen jitters, but the major disturbance
seems to be confined to the lower left quadrant. If this is an interaction
between the fan/video or the hard disk/video, is there a fix for it??? Is there
any fix for it??
I find this problem EXTREMELY annoying.
Help save my Mac! I really do like it except for the screen shake.
Thanks in advance,
Rich Longlriggins@afit-ab.arpa (L. Maurice Riggins) (01/13/88)
In article <8801122138.AA04420@decwrl.dec.com> long@viking.dec.com (Rich Long - LJ02 - DTN 226-2598) writes: >Hello everyone, > >This is my first USENET posting, so please forgive me if I do anything wrong! > >I'm having a problem with my Macintosh SE that I hope has a cure: It has had a >screen jitter almost since the day I bought it. > <deleted text> >Rich Long Rich, You're not alone. I bought one in June and had it back to the dealer by August. The screen was wavering in the upper left corner. He tried several things including replacing the crt. Bottom Line: Unplug the fan - the interference is gone! Of course, this was done with the case off... You couldn't leave it that way. His techs checked their Apple connection who confirmed the problem and said Apple was working on it (the checks in the mail). My dealer committed to provide the fix free if Apple does ever release one, free or not. The fan is a really poor design anyway...a noisy squirrel cage with closed ends, and the motor and wiring is close to the deflection coils of the crt. Yes, my problem is getting worse. I suspect it's because of dust collecting on the fan and slowing it down. Try this. Put your hand over the fan outlet blocking the flow. Does the interference increase? Maybe cleaning will help. NETWORLD - Anyone heard of a fix? Or as I've heard rumored is Apple only considering the SE a short term system not worth the recall (e.g. //c timing) of the tons of SE's they've sold. -- Maurice lriggins@afit-ab.ARPA
devoz@encore.UUCP (Joe Devincentis) (01/14/88)
[eat at joes] Two of us purchased 2.5 meg (20 meg hd) SE's in November. Both of these machines have extremely loud fans, and also suffer screen jitter in the upper left hand corner of the screen. We recently became registered developers, and ordered a development machine which showed up with 2 improvements; A quieter fan, and no screen jitter. I think apple has fixed the problem neh? devoz@encore Question: Is apple going to tell us how we get this done to our SEs? I would like a quieter fan even if it costs me some $$. The noise is disturbing.
graefe@tramp.Colorado.EDU (William S. Graefe) (01/14/88)
I read somewhere that the CMOS chips that are part of the display in the SE
are highly vulnerable to voltage spikes and can cause display failure.
Is this related maybe? Is this true?
I read this in either MacUser or MacWorld (can't remember)
!---------graefe@tramp.Colorado.EDU----graefe@tramp.UUCP---! ,---. !
! Bill |(insert something terribly witty, humorous, )! | _ _ !
! GraeFe, Jr.|(and inspiring in this space: )! `-+-' | !
!---------{sunybcs, hao,nbires}!boulder!tramp!graefe-------! `---' !tedj@hpcilzb.HP.COM (Ted Johnson) (01/15/88)
I bought an SE HD20 in June and have the same problem. It has had 2 hard disks replaced and has also had the analog board replaced (the fan ate itself), fortunately all under warranty. Since then the screen jitter continues, but it isn't really noticeable unless I look for it. I agree though, a FIX would be nice! -Ted
curry@nsc.nsc.com (Ray Curry) (01/18/88)
>Note about CMOS chip failure:
CMOS memory chips are more delicate than NMOS because the NMOS chips usually
have some sort of discharge path. However the subject wavering on the screen
I am sure is the same as on my machine which just makes the screen appear to
be moving slightly. This coupled with the whiter color of the screen over
my Plus screen, made the SE a little bothersome. I didn't mind but I am
someone that concentrates more heavily on the screen could find it objection-
able.
To reiterate what another posting said, it does appear to be caused by the
stock squirrel cage fan. I just returned from MacWorld Fair where I bought
the SE silencer fan and both fan noise and screen jitter have gone away.edg@pbhyg.UUCP (Elizabeth D. Gottlieb) (01/20/88)
In article <4917@nsc.nsc.com> curry@nsc.UUCP (Ray Curry) writes: >>Note about CMOS chip failure: > >CMOS memory chips are more delicate than NMOS because the NMOS chips usually >have some sort of discharge path. However the subject wavering on the screen >I am sure is the same as on my machine which just makes the screen appear to >be moving slightly. This coupled with the whiter color of the screen over >my Plus screen, made the SE a little bothersome. I didn't mind but I am >someone that concentrates more heavily on the screen could find it objection- >able. > >To reiterate what another posting said, it does appear to be caused by the >stock squirrel cage fan. I just returned from MacWorld Fair where I bought >the SE silencer fan and both fan noise and screen jitter have gone away. I'm jumping into this conversation late, so I don't know if my problem is the same as the "jitter" noted here --- does anyone know what could be causing a faint white line to scroll down my SE screen? It's a horizontal line across the entire screen, moves rather quickly. What could the problem be? (Naturally, it's no longer under warranty)... Thanks for any comments, Libby Gottlieb