[comp.sys.mac] a different kind of SE screen quirk

abr@mit-amt.MEDIA.MIT.EDU (Adam B Rosen) (10/19/87)

I haven't seen this one mentioned, though it happens on my SE with hard disk
and two of my friends' machines with double floppies.  When scrolling through
a large document, say in Word (any version) or downloading text via modem,
as the print scrolls up the screen the Mac makes a very faint 'pulsing'
noise with each line, vaguely reminiscent of an old teletype banging to the
next line.  It's a combination squeak and hissing sound, which is almost
(but not quite) drowned out by that 'ear splitting' fan so many people have
mentioned.  Any other noise in the room, such as stereos or conversation, will
drown it out, so check for this in quiet locations.

Has anyone else experienced this, or is this problem unique to these 3 Macs?

Adam B. Rosen

"Crutches are a reality for those who can't drug handles"
		-login quote on the media-lab computer last week

wade@sdacs.ucsd.EDU (Wade Blomgren) (10/19/87)

In article <1660@mit-amt.MEDIA.MIT.EDU>, (Adam B Rosen) writes:
> I haven't seen this one mentioned, though it happens on my SE with hard disk
> and two of my friends' machines with double floppies.  When scrolling through
> a large document, say in Word (any version) or downloading text via modem,
> as the print scrolls up the screen the Mac makes a very faint 'pulsing'
> noise with each line, vaguely reminiscent of an old teletype banging to the
> next line.  It's a combination squeak and hissing sound, which is almost
> (but not quite) drowned out by that 'ear splitting' fan so many people have
> mentioned.  Any other noise in the room, such as stereos or conversation, will
> drown it out, so check for this in quiet locations.
> 
> Has anyone else experienced this, or is this problem unique to these 3 Macs?

I most definitely have this same "problem" with my MacSE. Absolutely ANY 
program that scrolls text in a window causes this faint "screeching" or 
screaming.  As Adam says, it is not really loud enough to be too annoying. (It 
certainly does not anger me as much as my wiggling screen). An acquaintance of 
mine, upon hearing the description of this problem, surmised that it could 
actually be the 68000 processor (or the ROM?) doing the screaming, as the 
tightly looped set of ScrollRect calls is executed. He had seen a similar 
thing in a lab full of AT&T boxes. (Meaning that there was some fairly common 
activity that started those processors humming).  Harmonics in the silicon...
hmmm. A modestly loud stereo is the best solution I have found.

Regardless of the cause of this particular glitch (avoidable or not),
I am not impressed with the QC on the Macintosh SE.

Wade Blomgren
wade@sdacs.ucsd.edu

david@wiley.UUCP (David Hull) (10/21/87)

In article <1660@mit-amt.MEDIA.MIT.EDU>, (Adam B Rosen) writes:
> When scrolling through
> a large document, say in Word (any version) or downloading text via modem,
> as the print scrolls up the screen the Mac makes a very faint 'pulsing'
> noise with each line....

In article <458@sdacs.ucsd.EDU> wade@sdacs.ucsd.EDU (Wade Blomgren) writes:
> An acquaintance of 
> mine, upon hearing the description of this problem, surmised that it could 
> actually be the 68000 processor (or the ROM?) doing the screaming, as the 
> tightly looped set of ScrollRect calls is executed. He had seen a similar 
> thing in a lab full of AT&T boxes. (Meaning that there was some fairly common 
> activity that started those processors humming).

Well, my Mac SE does this too.  I just noticed it about a month ago
(I've had the SE for about six months now), so I don't know if the noise
started just recently or if it has been there all along.

I'm pretty sure that it's the power supply making the noise.  We had a
couple of Sun 2s at work that had the same kind of problem--executing a
program would cause it to make a loud buzzing noise.  Replacing the
power supply cured the problem.  I think that as the CRT and the 68000
draw current during a scroll it causes the power supply to make noise.

> Regardless of the cause of this particular glitch (avoidable or not),
> I am not impressed with the QC on the Macintosh SE.

I agree.  I've had mouse clicking problems, disk ejection problems,
the loud fan, and now this.  My screen doesn't normally wiggle, but I
can make it do so if I hold my hand over the fan outlet on the back.
Anyway, the noise isn't a catastrophic problem.  As you say, the fan
practically drowns it out.  But annoying, all the same.

-David
-- 
					---------------------------------------
					David Hull  TRW Inc.  Redondo Beach, CA
					  ...!{uunet,cit-vax,trwrb}!wiley!david

cjdb@sphinx.UUCP (10/29/87)

In article <1506@wiley.UUCP> david@wiley.UUCP (David Hull) writes:
>...  My screen doesn't normally wiggle, but I
>can make it do so if I hold my hand over the fan outlet on the back.

My SE screen display bulges in the middle horizontally every time I
start it up and the Welcome to Macintosh box appears. I don't see it
do anything funny at any other time. Possible explanations?


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