Toshiba U400 142 psu45e 00d005en no display blank screen

When powering your Toshiba U400 142 laptop you find there is no display and the screen is blank.

The first test is whether the laptop is actually powered. Check that the charger is plugged into the mains and that the mains supply is switched on and that the charger lead is plugged into your toshiba laptop. Verify that the DC power led on the laptop is illuminated. If it is not then investigate a possible laptop charger failure.

Press the power button on the toshiba u400 laptop and observe that the power led illuminated. Do you also notice the hard drive led flashing?

Did you see the BIOS screen on the laptop lcd screen or is nothing displayed at all on the laptop screen? If you see the bios screen then investigate a problem with the operating system causing it to not boot correctly or to hang.

If the laptop appears to be working but still nothing is displayed on the screen and it is blank then check that you have not accidentally switched the display source to the external monitor. Cycle through the display source keys ( usually a function key and one of the F-keys which will have a monitor icon printed or lcd/vga ).

With the laptop powered hold the laptop in bright sunlight or a really bright light or torch so that the lcd screen is illumined. If you can see a faint picture then the laptop is working but either the lcd screen, inverter or lcd screen cable is faulty. If you see signs of a dark liquid within the screen or leaking from the screen then the screen has become damaged by impact and you will need to replace the lcd screen.

To determine whether it is the inverter or the lcd screen is sometimes a case of flipping a coin. A good route to follow is to replace the inverter first as this is usually the cheaper of the two. If the symptoms persist after a new inverter has been fitted then you will need to change the lcd screen. The inverter steps up the voltage supply in the order of thousands of volts to power the tube within the LCD screen.

The lcd screen is made up of the TFT array, a controller board and a cold cathode tube or in some newer LCD screen an LED array. When the cold cathode tube fails then the screen is still working but it is just not illuminated so that you can see the picture. Think of it being just like a flourescent tube light in a kitchen.

These instructions can be applied to almost any laptop with no display on the screen. The toshiba u400 is fitted with a 13.3" tft lcd.

Viewed: 266 times.