Backlight problem - Aspire 5732z

JonCC

My daughter managed to break her LCD yet again. Unfortunately the first supplier provided an LCD (LED backlit) replacement assuring me that CCFL was no longer available as a replacement and that the LED backlit version would be compatible. After installing it, I got no screen and no backlight function. I subsequently contacted another supplier who managed to supply me the correct CCFL backlit panel, however this time on replacing the screen I found the CCFL backlight was not powering on.

 

My immediate thought was the inverter, and as a relatively cheap part I ordered another Inverter thinking it would fix the problem.

 

Alas no, the inverter did not fix the problem. To check the new LCD panel was working, I purchased an external CCFL inverter and confirmed that the LCF panel was working perfectly as once connected to the external inverter the backlight was fully functioning.

 

Having no means to test the output of the new inverter, I purchased a further inverter (from a different supplier - just to be certain it was not from the same batch.) Sadly this inverter gives identical result - no backlight.

 

My attention then turned to the laptop itself...had something blown effecting the feed to the inverter? This is where you guys hopefully come in. The input to the inverter has the following voltages - I have been unable to find any documentation to state what the acceptable ranges are, for the laptop output or indeed for the inverter input. Can anyone shed any light...no pun intended.

 

The figures below are as follows: Input Battery*, Input Mains*, Inverter circuit board (read from the PCB to ensure its not faulty connector.

 

• Green    10.6v                     19.42v                  19.41v
• Blue       10.6v                     19.42v                  19.41v
• Brown     0.04v to 0.08v        0.04v to 0.08v      0.04v to 0.08v
• Grey       3.31v                     3.31v* & 0.26**     3.31v*  & 0.26**  (FN+F6 *On *Off)
• White      0.51v                     0.51v                  0.20v/0.00v**  (Internal Screen On/Off in OS)

Would welcome any comments.

philetus

I know FN + F6 turns the backlight off and on.

JonCC

Unfortunately toggling FN+F6 doesnt switch the backlight on in this case, although as you will see from the voltage readings, it does have an impact on the input voltages.

philetus

Had any luck?

http://forum.notebookreview.com/sony/613996-no-backlight-led-screen-2.html

JonCC

Thanks for link. 

I am hoping Acer is going to supply me the input voltages for the Inverter...my gut feeling is something has popped on the mobo when the screen got damaged. If I apply 3 volts to the inverter input on pin 2 the backlight comes on and the monitor works perfectly....unfortunately the feed to that pin from the mobo is currently outputing 0.20v and nothing close by I can jump a 3v feed from.

 

Would be nice to think its the fuse, but presumably if it was I would have no voltage coming through, so am wondering if its a resistor thats popped.

 

 

philetus

Have you checked the lid switch that turns off the screen when the lid is closed?

JonCC

Yep. All works perfectly. Its the motherboard output to the inverter input connector - almost certainly something has failed. if I apply 1.5v to 3v to pin 3 the inverter switches on and the backlight works perfectly. Unfortunately the output from the mobo on that pin is 0.20v 

 

Lookslike i maybe tracing the fault on the motherboard shortly

 

Still hoping someone from Acer can provide me the correct voltage range.

philetus

A wide range of input voltages Though the input voltage range varies depending on the specific battery used in each application, the inverter needs to support battery voltages of approximately 5 to 15 V. When an AC adapter is used, however, even higher voltages are present. In some cases, the input voltages range more than 4 to 1.

http://www.mikrocontroller.net/attachment/1389/Application_Note_97.pdf

JonCC

Thanks for info.

Sadly Acer seem unable to supply me with the ranges that the mobo should be outputing