Screen suddenly goes dead since using a monitor on T21

[abrogard]

My T21 works well, usually.

A little while back I plugged a monitor into it and a usb keyboard and it has always had a serial mouse plugged.

For a while it worked well like that. No problems at all. The monitor screen would light up, the T21 screen would go black and we'd compute on, no problems.

Then the monitor screen started suddenly going black, like as though it were trying to run a screen saver (which it doesn't have - the computer I mean).

And we didn't know how to get the notebook to start using its own screen. So there was nothing we could do but a hard reboot.

So after a while of this behaviour and because we couldn't fix it we took the monitor off.

And the behaviour has continued but this time it is, of course, the computer's own LCD screen that is going black.

Can anyone help with how we can deal with this behaviour?

regards,

ab

[joester]

Assuming you are running windows, I would go to the display options (right click on the desktop and select properties\screen saver), then power settings.
Verify the power scheme selected isn't configured to turn the monitor off.

If it isn't that, you may have a motherboard problem.

[phelix]

I assume you've tried Fn-F4?

[abrogard]

Surely whatever power setting it has would only turn the screen off when the machine is unused for some time?

And I'm sorry I didn't make it clear but I mean this happens during the course of one's work. We're busily hacking away and the screen goes black!

However I'll check it as soon as I can.

No.. I haven't tried Fn/F4. I rather thought I'd tried every function key combination by simply holding down the Fn key and hitting all the function keys one after the other. Perhaps that method simply doesn't work because the previous keycode is still in the buffer or somesuch.

I don't have a list of function keycodes. Is one within the machine somewhere?

I'll try that key combination next time it happens.

What's intriguing me (beyond the necessity to get the screen working again) is just what is happening? Why would it do this? (During the course of work, I say again.)

regards,

ab

[rkawakami]

Ah, Fn+F4 puts the system into standby mode (wake it up by pressing the Fn key). I think what the "phelix" meant was Fn+F7, which cycles the active display between the LCD and an external monitor.

[abrogard]

The external monitor is now disconnected... I should make that clear.

The notebook itself blackens its own screen at unpredictable times...

I'm still waiting for it to happen again so's I can try Fn/F7

But why would it do it? Surely something is broken?

[rkawakami]

The next time it happens and before you try hitting the Fn+F7 combination, take a close look at the LCD and see if you can see any active pixels. Shine a bright light on the panel at an angle. If you see a "ghostly" image of your normal screen, that means the backlight has turned off for some reason. If the screen is totally blank, then the video signal (and backlight) has ceased to be delivered to the LCD.

Yes, in either case something is wrong. If the backlight has simply turned off you could have a problem with the inverter board (fairly cheap and easy to fix). Or, it's possible that there is a loose connection somewhere between the motherboard and LCD panel. If the entire screen is blank (no pixels) then there's several things that can be wrong. First thing to check is the lid closure switch. Located just in front of the right-side hinge, press it down a couple of times with a small screwdriver or pen. Don't push too far down, just flush with the keyboard bezel. If that makes the display return, you've solved the problem. If not, well, then try the Fn+F7 key sequence.

A list of Fn key actions is available in the Hardware Maintenance Manual, downloadable in Adobe Acrobat format from here:

T2x HMM

Page 48 lists the Fn combinations. There are also icons on each "F" key which should give you an idea what the Fn+F keypress does.

[phelix]

Ah, Fn+F4 puts the system into standby mode (wake it up by pressing the Fn key). I think what the "phelix" meant was Fn+F7, which cycles the active display between the LCD and an external monitor.

Yes, I meant Fn-F7 Sorry!