820-2530-A no backlight after liquid damaged.

Alan.L

Member
Board turn on to no backlight with (?) folder.

i've replacement U9701 because it has corrosion on pin21 and pin23.
Pin21's pad is gone, so i've run a wire to C9796.

LVDS connector looks good.


i get 12.55v on F9800 Fuse when connected LVDS cable.

i found problem...

R9809
pin1 4.1V (PPBUS_S0_LCDBKLT_EN_DIV)
pin2 0V (PPBUS_S0_LCDBKLT_EN_L)

R9808
pin1 12.55V (PPBUS_S0_LCDBKLT_FUSED)
pin2 4.1V (PPBUS_S0_LCDBKLT_EN_DIV)

Q9807
pin1 0V (Ground)
pin2 3.27V (BKLT_PLT_RST_L)
pin3 0V (PPBUS_S0_LCDBKLT_EN_L)
pin4 0V (BKLT_EN_L)
pin5 3.19V (LVDS_IG_BKLT_ON)
pin6 0V (BKLT_EN_L)
b4j2tg.jpg
 
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Alan.L

Member
Q9806
Pin1 12.55V (PPBUS_S0_LCDBKLT_PWR)
Pin2 12.55V (PPBUS_S0_LCDBKLT_PWR)
Pin3 4.1V (PPBUS_S0_LCDBKLT_EN_DIV)
Pin4 12.55V (PPBUS_S0_LCDBKLT_FUSED)
Pin5 12.55V (PPBUS_S0_LCDBKLT_PWR)
Pin6 12.55V (PPBUS_S0_LCDBKLT_PWR)


bad Q9806?
 

larossmann

Administrator
Staff member
Q9806 is doing its job. How can it be bad if it is passing power from input to output? Answer aprendiz's question!
 

Alan.L

Member
12.55 voltage on pin 23 from U9701

R9703 12.55v (PPVIN_BKL_R) This is on other side of the board.
 
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Alan.L

Member
R9701
Pin1 0v (BKLT_EN_R)
Pin2 3.1v (BKLT_EN)

C9714
Pin1 5.2v and fluctuating to 3.7v ish

C9711
Pin1 3.27v (PP3V3_S0)

R9731
Pin1 12.55v (PPBUS_S0_LCDBKLT_PWR)
Pin2 3.1V (BKLT_EN)
 

Alan.L

Member
i'll try replace the stock lvds connector to see if any help. since the connector is so close to u9701 ic.
 

Alan.L

Member
think i found a problem. u9701's pin23 and pin 24 is shorted together. i just removed and it is still shorted. so my replacement job was good.
i've also removed D9701 and it is still shorted. do i have a bad L9701 ?
 

Alan.L

Member
PPVIN_BKL_R and PPBUS_S0_LCDBKLT_PWR_SW not ment to not connected together right?. the schematic confused me a bit since the drawing look like they should be.
i dont have another known good board to test.
 
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Alan.L

Member
backlight is working now after i replaced L9701. but PPVIN_BKL_R and PPBUS_S0_LCDBKLT_PWR_SW is still shorted together. is this normal?
 
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