Re: LCD Monitor Problem - Turns on and off
- From: "Arfa Daily" <arfa.daily@xxxxxxxxxxxx>
- Date: Fri, 03 Mar 2006 23:57:35 GMT
"mistermaniac" <mistermaniac.2447p1@xxxxxxxxxxxxx> wrote in message
news:mistermaniac.2447p1@xxxxxxxxxxxxxxxx
Bill Simpson Wrote:
I tried to post this yesterday, but it didn't seem to show up.
Apologies if it's duplicated. Probably a Comcast problem.
I have a very unusual problem with an LCD monitor. I will try and be
descriptive as possible without being confusing.
When the adapter for the monitor is plugged directly into a wall
outlet, and there is always current to the wall outlet, I can turn the
monitor on and off normally. There are no problems.
When the adapter for the monitor is connected to my UPS and the UPS is
turned off and then back on, or when the adapter is plugged into a
wall outlet and then unplugged from the wall outlet and plugged back
in, I begin to have problems.
Specifically, in the two situations above, when booting the computer,
the monitor will "buzz" briefly, the picture will come on, and then go
off. It will do this several times during the boot sequence. It will
do it once at the bios, once at the Windows splash and then again at
the login screen. Upon each of the three occurrences mentioned, the
monitor will "buzz", the picture will come on briefly and then go off.
However.if I reboot the system several times, or when I'm at the last
login screen, turn the monitor on and off several times with its
switch, it will eventually stay on.
I have tested this monitor with different video cards and on different
systems, so it's not the video card or one specific box.
From the way the LCD is reacting, the problem seems to be similar to a
bad ballast in a fluorescent light, is this possible?
Any suggestions (except leave it plugged in all the time? Is there any
way to test this LCD with minimum equipment and knowledge?
Thanks in advance.
When the screen goes "off" does it really goes off? It sounds like a
bad inverter or a bad ccfl.
--
mistermaniac
Yes, you need to establish this. It is very possible, if the monitor is
genuinely not starting after a period of being totally unpowered, that the
problem is actually the external power supply, which is pretty much certain
to be a switch mode type. I have had a number of these giving similar
symptoms to those you state, the cause being bad electrolytics, particularly
on the primary side. In general, when switchers have this sort of problem,
once you've persuaded them to come on, and the caps have warmed up a bit,
they will stay on. Try measuring the output voltage of the power supply,
after it's been off for a couple of hours. You may well find that there
isn't any, or what there is, is pulsing. You could also try hanging a low
wattage car bulb across the power supply output - say an interior light
bulb - if you can figure a way of getting a connection to the output plug.
Arfa
.
- References:
- LCD Monitor Problem - Turns on and off
- From: Bill Simpson
- Re: LCD Monitor Problem - Turns on and off
- From: mistermaniac
- LCD Monitor Problem - Turns on and off
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