My Monitor Suddenly Doesn't Show Anything!

On May 9, 5:43 pm, Paul <nos....RemoveThis@needed.com> wrote:
> trunterzx wrote:
> > One day when I came back to use the computer, which was switched on, I
> > kept pressing the keyboard but nothing came onto the monitor. I
> > switched off the power and switched on again, the screen came out for
> > a while, and went off again. So I decided to unplug the power plug of
> > the monitor and plug it back, and somehow the problem was solved. But
> > now, the problem came back, and now unplugging and plugging the
> > monitor power can no longer solve the problem... Is my monitor spoilt,
> > or does the problem lie somewhere else?
>
> > Please help! Thanks.
>
> You don't say whether your monitor is an LCD, but I'll assume it is.
>
> The monitor has a backlight inside it. The LCD panel controls
> the transmission of light, and there is a light source behind
> the panel.
>
> The majority of LCD monitors have one or more CCFL (cold cathode
> fluorescent) lamps for backlights. They need 700 to 1000V AC to
> operate. A small rectangular circuit board has an "inverter",
> which converts a low voltage like the 12V DC inside the monitor,
> to the required high voltage AC to run the lamp. The AC is
> also at a high frequency, so there won't be any flickering.
>
> If the monitor lights up for a second or two, and then goes
> dark, that is the inverter shutting off. It means the
> inverter thinks it is overloaded, and so it has shut off.
> This can mean a failure of the inverter, or an actual
> short somewhere in the wiring (like dust or dirt forming
> a conductive path for the high voltage to flow). Sometimes
> the connectors on the inverter are corroded and make an
> unreliable connection.
>
> One test you could have tried, if you could still see the
> monitor screen, is turn down the intensity setting of the
> monitor. If you can do that, frequently the inverter will stay
> running for a while longer. But it won't last forever.
>
> This is really a shame for LCD monitors, because
> everyone worries about the CCFL (the lamp itself)
> and its 25000-35000 hour lifespan. But what seems
> to happen instead, is problems with the inverter
> mean never getting to see the lamp wear out.
>
> Inverters can be replaced - the hard part is finding
> an exact substitute. There are companies on the
> web that sell substitutes, but you never know how
> close they are to functioning like the original.
> I doubt any company sells the exact same module
> as the one inside your LCD monitor right now.
> If only the LCD monitor companies sold replacement
> parts, or were required to by law.
>
> Paul

Paul, thanks for taking the time to give all this very interesting
info on monitors. It's nice to know what's really happening "in
there".
ATB
sandy58
 >> Stay informed about: My Monitor Suddenly Doesn't Show Anything! 

This message is not archived
 >> Stay informed about: My Monitor Suddenly Doesn't Show Anything! 

Paul wrote:

trunterzx wrote: > One day when I came back to use the computer, which was switched on, I > kept pressing the keyboard but nothing came onto the monitor. I > switched off the power and switched on again, the screen came out for > a while, and went off again. So I decided to unplug the power plug of > the monitor and plug it back, and somehow the problem was solved. But > now, the problem came back, and now unplugging and plugging the > monitor power can no longer solve the problem... Is my monitor spoilt, > or does the problem lie somewhere else? > > Please help! Thanks. You don't say whether your monitor is an LCD, but I'll assume it is. The monitor has a backlight inside it. The LCD panel controls the transmission of light, and there is a light source behind the panel. The majority of LCD monitors have one or more CCFL (cold cathode fluorescent) lamps for backlights. They need 700 to 1000V AC to operate. A small rectangular circuit board has an "inverter", which converts a low voltage like the 12V DC inside the monitor, to the required high voltage AC to run the lamp. The AC is also at a high frequency, so there won't be any flickering. If the monitor lights up for a second or two, and then goes dark, that is the inverter shutting off. It means the inverter thinks it is overloaded, and so it has shut off. This can mean a failure of the inverter, or an actual short somewhere in the wiring (like dust or dirt forming a conductive path for the high voltage to flow). Sometimes the connectors on the inverter are corroded and make an unreliable connection. One test you could have tried, if you could still see the monitor screen, is turn down the intensity setting of the monitor. If you can do that, frequently the inverter will stay running for a while longer. But it won't last forever. This is really a shame for LCD monitors, because everyone worries about the CCFL (the lamp itself) and its 25000-35000 hour lifespan. But what seems to happen instead, is problems with the inverter mean never getting to see the lamp wear out. Inverters can be replaced - the hard part is finding an exact substitute. There are companies on the web that sell substitutes, but you never know how close they are to functioning like the original. I doubt any company sells the exact same module as the one inside your LCD monitor right now. If only the LCD monitor companies sold replacement parts, or were required to by law. Paul

Thanks for the info. Sorry I forgot to say more about my monitor. It's a BENQ monitor, and the model is Q7T4.



So if the inverter is spoilt, does that mean I have to go and get a new monitor? One thing I forgot to mention is that the green lamp which indicates that there is signal from the computer remains on all the while even when the monitor does not show anything. And the monitor takes a longer time to go off when I leave the computer switched off for a long time. Could it be a problem of the graphics card? I'm using GeForce 8600.
 >> Stay informed about: My Monitor Suddenly Doesn't Show Anything! 

trunterzx wrote:

>
> Thanks for the info. Sorry I forgot to say more about my monitor. It’s
> a BENQ monitor, and the model is Q7T4.
>
> http://imagenes.solostocks.com/media/3/8/6/media_1418683.jpg
>
> So if the inverter is spoilt, does that mean I have to go and get a
> new monitor? One thing I forgot to mention is that the green lamp
> which indicates that there is signal from the computer remains on all
> the while even when the monitor does not show anything. And the
> monitor takes a longer time to go off when I leave the computer
> switched off for a long time. Could it be a problem of the graphics
> card? I’m using GeForce 8600.
>

For an inverter problem, there are a couple possible symptoms. There
may be no light ever, coming out of the screen (complete failure).
There can be light for 2 seconds, followed by darkness. That is the
inverter shutting down on an overload. That means the inverter is
"weak", and can no longer support the load the CCFL lamp is presenting.

The LCD screen works on light transmission. If you could, somehow,
shine a light through the back of the screen, you'd see that the
screen was still working. It is just the light source that has
died.

There are web sites that sell replacement inverters, but I don't know
what the odds are that you'll successfully repair the monitor.
For a consumer, the easiest solution is to buy a new monitor.
It all depends on how much time you want to spend on it.

You'll notice here, that the people running this site, are making
a hefty profit. Which doesn't help matters either.

http://www.lcdpart.com/doc/inverter.html

An inverter can drive more than one lamp. Some of these little boards
drive a number of lamps. And in some of the larger display devices,
there can be multiple of these little boards. Obviously, at the LCD
monitor factory, they're not paying $69.99 for each inverter, or
monitors would be ungodly expensive. If the monitor cost $300, it
hardly makes sense to spend $100 on a repair that might not work.
If the monitor is really expensive, or a high quality one, then by
all means, try to repair it. If the monitor cost $1000, then $100
gamble is worth it. But at the $300 level, it'll be a decision
based on your own skill level at disassembling and repairing things.

(Example of an inverter)
http://www.lcdpart.com/Products/lg1501.html

Examples of installation procedures. Downloadable PDF shows how many
screws and whether things need to be pried apart or not.

http://www.lcdpart.com/doc/inverter_installation.html

There are way more monitor brands and models, than there are
suppliers selling replacement inverters. So you may not even find a
match for your model. Which makes the decision to buy a new
monitor, an easy one.

Paul
 >> Stay informed about: My Monitor Suddenly Doesn't Show Anything!