820-3462 Backlight Fuse (F9700) keeps blowing

[StraightToThePoint]

820-3462

PPBUS_G3H - 12.6V when fuse is soldered and desoldered.

Replaced with 3-4 fuses, keep blowing.

No corrosion or liquid damage signs on the backlight circuit (Around Q9707) or around the LVDS connector.

Any tips, I will be happy to report back voltages of other chips too.

 

[2informaticos]

Post diode mode (red probe at ground) on both pines of D9701; w/ and w/o LCD connected.

Never power up a board directly after changed a fuse.
There should be a reason for that; you must find it first...

 

[StraightToThePoint]

Post diode mode (red probe at ground) on both pines of D9701; w/ and w/o LCD connected.

Never power up a board directly after changed a fuse.
There should be a reason for that; you must find it first...

Without LCD connected
Pin 1 - 220 K ohms
Pin 2 - 60 Ohms

With LCD connected
Pin 1 - 220 K Ohms
Pin 2 - 50 Ohms

 

[2informaticos]

Do NOT quote an entire post visible few centimeters above.
Please maintain forum aesthetic...

You have a problem on the MLB; LCD assembly should be good.
Check all 2.2uF filter caps from backlight output.
Also inspect LCD connector.

BTW, for the future use schematic points for reference, not from boardview; like K of D9701, instead of pin2.
We use schematic for assistance, not boardview.

 

[No-Clean]

Just in case someone comes back in here like I did make sure to check the LCD cable in diode mode on pin 1 if you keep blowing fuses. In one repair I did the cable connector looked perfect but it was shorted on the inside of the LCD, remove the plastic cover on the LCD lid, remove the bad cable, clean the connector on the LCD lid, inspect it with the microscope and clean well, put new cable and check diode mode on pin 1 again, if there is no short also check for continuity back to the connector to make sure you are good, replace fuse and done!