testing laptop system board

[phalsedoom]

Anybody know of sites or books that would give information about testing the circuitry of a laptop system board? I have a dead system board for a toshiba laptop. Well it boots, but it will not work with the display so i have to use an external monitor. The laptop screen works so it must be a problem with the board. in addition this board will not work with the battery, only ac plug. So, i figured i would try to learn something new and toy around with this thing. but i am wolefully ignorant whne it comes to circuits and the like. So, that is the function of this call for help.

 

[Bozz]

Oh, if they only existed

I can call myself a specialist compared to most who have had no official training with Toshiba laptops.

What model is it because the faults you describe sound much like an open circuit FET in the onboard DC-DC power supply of the laptop. Tracing faulty FET's is a pain in the @ss because they measure open circuit even when in serviceable condition so you can be stuck at it for hours. I have never found any good sources of information about pinouts of various IC's used in laptops such as the switchmode power supplies, I reckon they like to conceal information to avoid other companies easily stealing intelectual property and who can blame them. I have fixed many boards mainly with obvious faults but I am unable to fix more than I can fix.

The reason I am inclined to suggest it's the onboard DC - DC converter is because you say it has multiple problems and multiple problems are usually related to a common source. Another reason I believe that is because you do have video out but no picture on the LCD. This could be a very simple fix, get a torch and shine it into the LCD to check if you can see the screen operational. This would suggest the high voltage cold cathode flourescent backlight lamp inverter is not working...

It would be unlikely to be anything other than the power supply or a microcontroller IC that controls functions such as switching the inverter on/off, switching the charging cct on/off etc etc etc....

Reply with the model number of the laptop and I will see if I can assist you further.

Cheers

 

[phalsedoom]

Thanks a lot for the info. the model number is satellite 2100cdt. I also have a system board for a 1605cds. But on that one the problem is the machine will not power up at all except for the light. But anyway, thanks for the assistance. I think this will be a really cool project if I can just get some more info.