3 Apr
2018
3 Apr
'18
1:07 p.m.
Hi all,
Recently booted up my B&W Powermac G3, all came up fine including the 17? CRT monitor.
However after a second or so, the
monitor gives a ?popping? sound and the image on the screen expands then shrinks. This
repeats every few seconds.
I?m guessing the monitor is on the way out - but as this is a complete B&W system - I
wondered what the likely cause is?
Thanks
3 Apr
3 Apr
1:48 p.m.
On Tue, 2018-04-03 at 21:07 +0100, Ian Frost via cctalk wrote:
Recently booted up my B&W Powermac G3, all came up fine including the
17? CRT monitor. However after a second or so, the?
monitor gives a ?popping? sound and the image on the screen expands
then shrinks. This repeats every few seconds.
I?m guessing the monitor is on the way out - but as this is a
complete B&W system - I wondered what the likely cause is?
That sounds like some sort of problem with the EHT supply. If the
picture is stable until the first pop and then it expands, that might
suggest that the EHT voltage is dropping because of some sort of sudden
spark discharge. Does the image also get dimmer/fainter at the same
time? Can you see any evidence of arcing inside the monitor when this
is happening? ?
I guess it's not impossible that slightly-conductive dust might have
built up inside the monitor somewhere to the point where the EHT
insulation is compromised and it's flashing over. If that's the
problem then a bit of a clean-up might be all it takes to fix it.
Needless to say, be careful when cleaning around the EHT.
Conversely, if the image was to get initially smaller and then suddenly
expand with a "pop", that might suggest that the EHT supply regulation
has gone wrong and the voltage is going too high. From what you've
described though it doesn't sound as though that's what is happening.
p.
2:09 p.m.
On Apr 3, 2018, at 3:48 PM, Phil Blundell via cctalk <cctalk at classiccmp.org>
wrote:
On Tue, 2018-04-03 at 21:07 +0100, Ian Frost via
cctalk wrote:
https://en.wikipedia.org/wiki/Apple_displays
indicates:
?.The Apple Studio Display series of CRT displays were available in a 17" Diamondtron
and a 21" Trinitron CRT, both driven by an LG-Manufactured chassis. These displays
were notorious for faulty flybacks. ?
</instant wikipedia expert >[
Would that be consistent with the symptoms, and is there a good way to test?
- Mark
Recently booted up my B&W Powermac G3, all came up fine including the
17? CRT monitor. However after a second or so, the
monitor gives a ?popping? sound and the image on the screen expands
then shrinks. This repeats every few seconds.
I?m guessing the monitor is on the way out - but as this is a
complete B&W system - I wondered what the likely cause is?
That sounds like
some sort of problem with the EHT supply. 
5:58 p.m.
?.The Apple Studio Display series of CRT displays were
available in a
17" Diamondtron and a 21" Trinitron CRT, both driven by an
LG-Manufactured chassis. These displays were notorious for faulty
flybacks. ?
those are both COLOR, aren't they?
Not that it couldn't be flyback, but those two would presumably be
unrelated to a B&W CRT.
6:08 p.m.
On 2018-04-03 8:58 PM, Fred Cisin via cctalk wrote:
They are colour. In this context, B&W means "blue and white", as in the
G3 tower (and monitor) colour scheme. Pinstripy if I recall correctly.
--Toby
?.The Apple
Studio Display series of CRT displays were available in a
17" Diamondtron and a 21" Trinitron CRT, both driven by an
LG-Manufactured chassis. These displays were notorious for faulty
flybacks. ?
those are both COLOR, aren't they?
Not that it couldn't be flyback, but those two would presumably be
unrelated to a B&W CRT.
4 Apr
4 Apr
1:13 p.m.
On 04/03/2018 08:08 PM, Toby Thain via cctalk wrote:
They are colour. In this context, B&W means
"blue and white", as in the
G3 tower (and monitor) colour scheme. Pinstripy if I recall correctly.
I never thought I'd see B&W in the context of displays mean anything other
than black & white, but of course in a discussion about Apple hardware,
anything is possible :-)
1:37 p.m.
They are
colour. In this context, B&W means "blue and white", as in the
G3 tower (and monitor) colour scheme. Pinstripy if I recall correctly.
I never thought I'd see B&W in the context of
displays mean anything other
than black & white, but of course in a discussion about Apple hardware,
anything is possible :-)
It is sometimes surprising where terminology becomes ambiguous.
At the college, with a few dozen 5150s, we used CGA cards with cheap B&W
composite monitors, including some that were marketed for CCTV. THAT
permitted us to afford substantially more machines than either IBM CGA
color monitors OR IBM "monochrome" card and monitor. That was before the
aftermarket reached full saturation.
But, when shopping for cheap composite monitors, when you asked about B&W
monitors, you would often get told that they had none. because what they
had were green or amber phosphor.
If you asked for monochrome, then they started in with monitors compatible
with the IBM MDP/MDA or Hercules cards.
What is the minimum phrase that will unambiguously (or minimum ambiguity)
specify B&W (of any color of phosphor) with composite input?
YES, the IBM monochrome monitor, or later after-market with Hercules
compatible cards, IS a much better image. But, for running a text editor
and a compiler, the choice was between 15 computers with CGA color, 20
with IBM monochrome, or 30 with CGA and cheap composite monitor. Our
priority was to try to have almost enough machines for the number of
students. And contrary to demands from SOME instructors, you do NOT need
color to learn to use WordPervert, Lotus, or programming tools. Later,
when we were finally using generic 386SX machines, we had an instructor
who was teaching a course on Unix, who insisted that all the machines had
to have VGA. Again - enough minimal machines for everybody, or half
enough machines with fancy preferred hardware?
--
Grumpy Ol' Fred cisin at xenosoft.com
2405
days inactive
2406
days old
6 comments
6 participants
participants (6)
-
cisin＠xenosoft.com -
jules.richardson99＠gmail.com -
mtapley＠swri.edu -
pb＠pbcl.net -
silvercreekvalley＠yahoo.com -
toby＠telegraphics.com.au