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Mohamed Kamel
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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 |
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SBA
Передовик
Сообщения: 1293
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| There is very easy way - desoldering BKOFF# pin kb930. After this, you can decide to change kb930, or try to find something else. |
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Mohamed Kamel
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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 |
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Mohamed Kamel
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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 |
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