Monitor won't power up when connected to power source. Blue power icon lights up momentarily before going dark again. Used multiple power cords in a vain attempt to assure it wasn't my cord. Checked outlets to ensure no breaker was flipped. Problem persists. Anyone have any other ideas?

disconnect the power adapter 2) disconnect the battery too 3) Press the power and hold the switch button power by 60 seconds. Then proceed in reverse and Power again and can be fix it.Of course if the problem remain test the memory from your pressing the key f2 or f9 depending of your modell in the reboot and go to the test memory.
God bless you

check caps

this is not a pc problem... this is because the connection loss between pc and monitor... not all pc's have sleep mode in externa vga connection.... it just cuts power off... u can configure monitor of possible to do that..

Screen won't come on when? When you first hit the power button to boot it up? Does anything ever post to the screen when you hit the Power Button? Or does it seem like it booted up all the way (you hear the fan running, you hear the hard drive spinning) except the screen is black?

If it seems like it booted up all the way except the screen is black try the steps below.

Shine a flashlight on the dark screen to see if you barely see the icons on the desktop. If so, then the LCD Inverter is bad.

Plug in an external monitor and see if the display shows up on it. It can be any kind of monitor even the old big fat crt monitors as long as it has a vga cable to connect to your computer's vga port. If so that proves your video card is ok. The video will show on most systems when you reboot without you having to do anything. Some systems will require you to hit the FN (Function key) + F1 thru F12. Hold down the FN key then hit the correct key for displaying on the monitor (F1 thru F12). The correct key will normally have CRT/LCD on it or it will have the icon of a display.

If you see no icons by shinning a flash light and the external monitor works, then your screen is bad. If you see no icons by shinning the flash light and nothing shows on the external monitor, then most likely your video card is bad.

If it does not seem like it booted up all the way try the steps below:

When you plug in the power cord is there any lights whatsoever on the laptop, where the plug goes in or on the AC Adapter of the power cord?

When you press the power button do you hear fans running, hard drive spinning, lights on the computer, hear any beeps or lights constantly blinking, hear the DvD/CD drive click and the light on the drawer of the DvD/CD turn on for a second or two? If so the laptop is trying to boot or may have booted, but the screen is not showing for some reason.

Beep tones and blinking lights tells the technicians what is going on with the laptop and why it is not booting. Most times it's a motherboard issue when you hear beeps or blinking lights continuous. Most times the problem is with the memory or Video Card. Count the Blinking Lights or Beeps and take note of their pattern (1 Long or 1 Long followed by 2 Short).

Maybe your power cord is bad if you don't get anything to happen whatsoever when you press the power button. And if that's true maybe you was operating off the battery the last time you had it on and since the power cord is bad, it was not charging the battery so the battery is drained and the power cord is bad.

Maybe you have a Static Charge Buildup. Remove the Power Cord, Remove the Battery, then Press and Hold the power button for 30 seconds. After 30 seconds plug the power cord back in (leave the battery out) and hit the power button to see if it boots. If it does, you can put the battery back in and let it charge.

Maybe your DC Power Jack which is where the power cord plugs into the computer is bad. Take an ink pen and push the tip inside the jack and see if the little pin wiggles, if so the jack is bad. You'll have to take the laptop apart to fix it. Most times it is soldered onto the motherboard, so you will have to desolder the old and solder a new one.

Maybe your memory is bad or the memory slot is bad.

Remove the Power Cord, Remove the Battery, Remove the cover that houses the memory on the bottom of the laptop then remove one of the memory chips. Set the chip aside then try rebooting the computer. If it boots, then you know the memory chip you set aside is bad so mark an x on it with an ink pen. If it fails to boot then move the chip to the next memory slot and try rebooting. If it fails take the chip out and set it aside, then put the other chip in and try booting it in both slots. If it boots, just to verify that the chip set aside is bad, mark an x on it and put it into the open memory chip slot and try booting.

This is strange.
I think your ac adapter power cord is bad. Get another one from ebay at: http://www.ebay.com

Just put in your computer's make and model, not the model of the battery in the ebay search.

For example: Toshiba Satellite Pro L300 AC Adapter

It might be your lcd screen's inverter, but it's strange. Anyway test the inverter by plugging in the ac adapter and when the screen goes blank try the steps below.

Shine a flashlight on the dark screen to see if you barely see the icons on the desktop. If so, then the LCD Inverter is bad.

Plug in an external monitor and see if the display shows up on it. It can be any kind of monitor even the old big fat crt monitors as long as it has a vga cable to connect to your computer's vga port. If so that proves your video card is ok. The video will show on most systems when you reboot without you having to do anything. Some systems will require you to hit the FN (Function key) + F1 thru F12. Hold down the FN key then hit the correct key for displaying on the monitor (F1 thru F12). The correct key will normally have CRT/LCD on it or it will have the icon of a display.

If you see no icons by shinning a flash light and the external monitor works, then your screen is bad. If you see no icons by shinning the flash light and nothing shows on the external monitor, then most likely your video card is bad.

Jeff, connect an external monitor for a diagnostic test.

Laptop OFF, monitor OFF, connect a VGA monitor to the VGA port on the back of the laptop,
(RGB/Monitor connector,

http://en.wikipedia.org/wiki/VGA_connector )

The external/VGA monitor can be a CRT type (Looks like a small TV), or a flat LCD screen that has a VGA cable.

Turn the external monitor on. If a CRT type allow it to warm up.
Turn the laptop on.

By default the display should show on the external monitor. If not press, and hold down on the Fn key, and tap the F5 key. (One of the Hot Key's)

If the display still does not show, hold down on the Fn key, and tap the F5 key again.
There are three display options;

1) Internal monitor of laptop ONLY
2) Internal monitor of laptop AND external monitor
3) External monitor ONLY

If graphics show on the external monitor, you have a problem in the Display Assembly, and/or the Video Cable.

If graphics do Not show on the external monitor, you have a problem with the graphics chipset on the motherboard.
(ATI Radeon 3100)

http://www.irisvista.com/tech/laptops/Toshiba-Satellite-Pro-L450-L455/laptop-disassembly-1.htm

Video Cable
1) Could be the connections. The connection of the video cable TO the motherboard, and the other end of the video cable TO the back of the LCD screen. (In the Display Assembly)

2) Could be damage to the video cable. Check the sheath of the cable for obvious signs of damage. If so, the thin tiny wires inside may be damaged also.

Cable should be checked for continuity of each wire in the cable. (Ohm's with a multimeter)

Video Cable condition, and tightness of connections check out, it's on to the screen Inverter.

Primer:
An LCD screen does not produce light by itself. It needs an additional light source.
A Backlight is the additional light source.

A Backlight is a CCFL, or a series of LED lights.

The Toshiba Satellite L455D-S5976 Notebook PC, uses 1 single CCFL for a Backlight.
Cold Cathode Fluorescent Lamp.

Similar to Fluorescent lighting used in homes, and businesses, but on a MUCH smaller scale.

A screen Inverter is used to convert the power (Electricity) from the laptop, for the LCD screen, and Backlight.

90 PERCENT OF THE TIME the fault is the Inverter.

The screen Inverter is a small rectangular circuit board, and is located behind the Display Bezel, an at the bottom of the LCD screen,

Example of screen Inverter,

http://www.battery-stores.co.uk/laptop-inverter.php/toshiba_Satellite+L455D-S5976_205_5226.htm

Link to a free Service Manual for the Toshiba Satellite L455D series of Notebook PC's,

http://www.tim.id.au/blog/tims-laptop-service-manuals/#toc-toshiba

Under the main Toshiba heading go down to the subheading -
Satellite A10. (A10 is in blue)
In this 'paragraph' go down to the third line, and scroll across to -
L450D, in blue.
Click on L450D.

This is a PDF file. The computer you are using now has Adobe Reader on it, which uses PDF files.
After you click on the file name { L450D } it may take up to 30 seconds before the first page comes up.

Would appreciate it if you would post back in a Comment with your findings.
Regards,
joecoolvette

If the monitor is a multiple source monitor then it could be stuck on an incorrect source or may not support auto source detection. See if there is a button to change the source. This will typically, but not always, be labeled source or have an icon that looks like a square with an arrow.
If there is no way to change the source or it is a single source monitor then you should see if it works on another system.
Since you shared that there is normally a dell monitor on the system then it is safe to say the computers video output is working correctly, but it is possible that the Gateway monitor will not work with the older hardware of the system.
I wish you the best of luck

First when you power up the computer press F8 key then enter in enable vga mode.
If you are able to enter then go to start menu->control panel->display property ->settings.
Change screen resolution to 1024*768 then apply and ok.
But if you are not able to see safe mode and other menu.
Then open cpu cabinet .
Refix RAM memory.
Pull cmos cell from motherboard for 10 minutes.
Reattach all connection harddrive.
Open processor fan and processor remove dust from all parts.
Make sure motherboard is not ground with cabinet.
Remove PCI cards if any.
After all above still same then change RAM then try.
Let me know if you need further assistance.
Thanks for using FixYa.

it may simply be a lose connection with the monitor cord. or the monitor cord may to be replaced.

From what I understand there may be a problem with the power circuitry used to light up a small fluorescent light that is the actual light source for the display. The TFT display itself doesn't produce it's own light, and if you point an external light source to the display and see program windows & other things the display itself is fine. Your problem can be solved with relative ease, but only in a computer service because it demands some components to be changed.