Packard Bell EasyNOTE TK backlight problem

[dicky96]

Hi guys, I don't fix many laptops so I am not totally familiar with this fault

I have the Packard Bell EasyNOTE TK laptop

The fault is no backlight. I get a picture on an external monitor connected to either VGA or HDMI, and if I shine a torch on the laptop screen I can see I have an image but no back light.

The fault was initially intermittent, the laptop would work for 10 minutes after power on then the screen would go black. Sometimes it would last for a longer time, enough time to install windows and some apps, and then go black.

But now it seems to be a permanent fault.

The problem still occurs if I remove the HDD so it is not a software issue.

This is a CCFL screen and has an inverter

I checked by setting my oscilloscope to the most sensitive range and holding the probe right next to the inverter transformer but I can't see any pulses as I would expect, or if I do they are an extremely low amplitude and could just be background noise

I also tried setting my Fluke DMM to Hz mode and holding the probes by the inverter. Nothing.

I checked the voltages on the input connector

pin 1& 2 = 18V
pin 3 = 5V
pin 4 = 3.3V
pin 5 = 0.2V
pin 6 & 7 ground

See pics for more details.
Can anyone tell me is the inverter faulty or is it not getting an enable signal?

Thanks


On the input connector I

[peste]

Re: Packard Bell EasyNOTE TK backlight problem

usually this problem is caused by the inverter or, and the CCFL lamp ... remove the plug from the inverter that leads to the CCFL lamp,
and install another test lamp, or other test display.

[String2016]

Re: Packard Bell EasyNOTE TK backlight problem

Agree with peste, I have same problem before I solved the problem by replacing sa ccfl inverter