Amstrad alt 386sx screen not coming on help please

[traindriver69]

Hi all
I have been trying to get working an Amstrad alt 386 laptop all I was getting was a green power light I have replaced the capacitors in the power supply and now it sounds like it is trying to do something but the screen is completely black so I don't know what it is doing but when I turn the power off there is a flash on the screen for a second.
I have checked the voltages from the power supply to the screen and these seem correct.
any help would be much appreciated.

 

[ptp170]

Watch my Amstrad ALT 286 videos on YouTube. One of the parts mentions about a negative voltage required to make the screen function.

 

[traindriver69]

Hi
Yes I have watched your videos and the voltages. Match what you say were needed but screen black.