problem with display - toshiba satellite 1800-400 HELP please

[pm]

Hello,

I've got a Toshiba Satellite 1800-400 laptop with following specs:
proc: Intel Celeron 800 MHz
HDD: 15 Gb
RAM: 256 Mb
op. sys: Win XP Pro SP2

Problem:
monitor is switching off so often that I can't use it any more. At the
beginning (=3-4 days ago) it was going down after 1-2 hours of normal
work, now it does it right after switching the comp on. It's not
completely turned off - where is a little button that turns the monitor
off then you close it and when I press it - monitor blinks and displays
properly (but only for this blink...). External monitor works fine when
I plug it in.

What I've tried:
- I switched off (and tried different settings of) power settings, in
BIOS and in Windows
- I removed Win Pro and installed Win 98 instead
- I didn't manage to update the BIOS because my floppy drive doesn't
work ;-/
- I removed all programs and updates from last period

I've no idea what it can be and I didn't find any hint in google search.
I hope any of you can help me with it!!

thanks a lot!!!

P.

 

[Paul]

Hello,

I've got a Toshiba Satellite 1800-400 laptop with following specs:
proc: Intel Celeron 800 MHz
HDD: 15 Gb
RAM: 256 Mb
op. sys: Win XP Pro SP2

Problem:
monitor is switching off so often that I can't use it any more. At the
beginning (=3-4 days ago) it was going down after 1-2 hours of normal
work, now it does it right after switching the comp on. It's not
completely turned off - where is a little button that turns the monitor
off then you close it and when I press it - monitor blinks and displays
properly (but only for this blink...). External monitor works fine when
I plug it in.

What I've tried:
- I switched off (and tried different settings of) power settings, in
BIOS and in Windows
- I removed Win Pro and installed Win 98 instead
- I didn't manage to update the BIOS because my floppy drive doesn't
work ;-/
- I removed all programs and updates from last period

I've no idea what it can be and I didn't find any hint in google search.
I hope any of you can help me with it!!

thanks a lot!!!

P.

Inside the LCD screen of the laptop, there is a "backlight".
The light is probably a cold cathode fluorescent lamp (CCFL).
The CCFL is powered by an inverter circuit, and the inverter
makes high voltage. It is probably the inverter that is
overheating or defective. The CCFL lamp is good for 20000
hours operation or so - since you were able to get it to
run for 1-2 hours, it might still be good.

This is an example of an inverter circuit.

http://www.fairchildsemi.com/markets/buck_royer.html

That looks a lot like a flyback circuit. The transistors commutate
the +12V, drive the transformer primary, and high voltage AC comes
out of the secondary. The voltage is quite high, like 700 or 800VAC,
but delivered at a low current (5 milliamps).

To see pictures of someone ruining/repairing their laptop, go here:

http://www.fonerbooks.com/laptop_5.htm

It might be easier to continue to use the external monitor.

Paul

 

[pm]

Inside the LCD screen of the laptop, there is a "backlight".

http://www.fairchildsemi.com/markets/buck_royer.html

Paul

thanks a lot! I unplugged this inverter and plug it again and now it's
working again! I don't know for how long ;-) But I've found where to buy
this spare part so I think I'm covered now.

Cheers!

P.

 

[kony]

thanks a lot! I unplugged this inverter and plug it again and now it's
working again! I don't know for how long ;-) But I've found where to buy
this spare part so I think I'm covered now.

If that's all it took, you might try cleaning the contacts.

It might help future readers with same problem if you post
the make and model of monitor, invertor #, and/or where you
found the replacement.

 

[pm]

kony wrote:
(...)

It might help future readers with same problem if you post
the make and model of monitor, invertor #, and/or where you
found the replacement.

Sure,
specs of my comp are here:
http://www.toshiba-europe.com/computers/products/notebooks/satellite1800_400/techspecs.htm
and some details about inverter:
- number on the white sticker: C1639786
- numbers next to word 'TAMURA': HBL-0220 E-P1 70881, YMX-F4A
- number above the 'caution: high voltage': UA2031P01
- number on the little white background in the middle of inverter: 15B2


P.