ESpec - мир электроники для профессионалов


acer aspire 7750 (LA-6911P rev:1.0) dim display on lcd

  Список форумов » Ноутбуки и КПК

Следующая тема · Предыдущая тема
АвторСообщение
Mohamed Kamel 
Новичок
Сообщения: 13
 
Сообщение #1 от 10/04/2014 14:05 цитата  

Hi!
acer aspire 7750 display is ok on external monitor, but dim on led lcd.
Tested with another working lcd, always dim display.

Main Voltages measured on JLVDS1 connector pins :
+INVPWR_B+ : 21V
Local_Dim_R : 0.8 to 1.1V
INVTPWM : 3.6V
+3VS : ok
+LCDVDD : 3.6v
+5VS : ok
But BKOFF# : 0V ??? issued from EC kb930QF
BKOFF# resistance to ground measured about 4 ohms ??

I guess that BKOFF# should be around 3v to enable backlight.

Do I have to replace the EC to get BKOFF# high and enable backlight ?

Please advise further.
Thank you
SBA 
Передовик
Сообщения: 1293
SBA
 
Сообщение #2 от 10/04/2014 21:02 цитата  

There is very easy way - desoldering BKOFF# pin kb930. After this, you can decide to change kb930, or try to find something else.
Mohamed Kamel 
Новичок
Сообщения: 13
 
Сообщение #3 от 11/04/2014 01:59 цитата  

I do agree with you. It's the easiest and most reliable way, though I often avoid handling pins of large chips singly as they are prone to break easily.

I'll go on and feed back.

thank you
Mohamed Kamel 
Новичок
Сообщения: 13
 
Сообщение #4 от 25/04/2014 21:51 цитата  

Wish to share members, how I solved the acer aspire 7750 dim display issue.
As BKOFF# signal was low, and resistance to ground about 4 ohms, I lifted BKOFF# pin of kb930 as suggested by "SBA", and it's resistance to ground went high, but 3.3V was always absent. I traced from BKOFF# pin of JLVDS1 back to EC kb930 & found R342 is missing, fixed a new one, BKOFF# went then high and display came

Перейти: 
Следующая тема · Предыдущая тема
Показать/скрыть Ваши права в разделе

Интересное от ESpec


Другие темы раздела Ноутбуки и КПК



Rambler's Top100 Рейтинг@Mail.ru liveinternet.ru RadioTOP