820-00281 A1707 Battery use -> no backlight...

[Mortentoft]

Hey guys.
I have an 820-00281 A1707 15'' which teases me a lot. First of all; The logic board is in excellent condition. Absolutely clean and looks new.
The problem is that the machine works and runs perfectly normally when the battery is unplugged. When I have the original battery in it boots as it should, but quite quickly the backlight flashes and then goes out. It takes 20 v and charges the battery with 3.9-4.0 amp, but the backlight disappears. Without battery: normal power consumption
I have tried three different batteries and it does the same thing.
I think it might be U5000 (SMC problem) and will look at TCON_BKLT_PWM line tomorrow at the office. If anyone has an obvious solution, I'd like to hear it

Thank you all and especially 2informaticos who allways gives good vibes and advices.

Good night

 

[2informaticos]

Same behavior with battery alone (no charger connected)?

If charger and battery both connected, backlight still stays off, if you disconnect J6951?

Check U5255 signals.

 

[Mortentoft]

Hi again. Finally Got the lb out (Damn lot of screws. U5255 is well… pp3v3_g3h is Stable and is 3.3 as it should. Had a tiny solderball from pin 6 (3gh). But nothing short… Could it be roastet?

 

[2informaticos]

I was expectingto get U5255 input and output voltages, when you don't get backlight.
Use boardview to find easiest points for test.

 

[Mortentoft]

Sorry… misunderstood… i vil find it for you

 

[Mortentoft]

Hi again 2informaticos. I screwed up… I thought after unplugging all the connections between housing and LB it works with and without the battery. What is wrong with the topcase? I do not know but something interfear with the backlight. Take a look at the picture battery and screen alone works fine but when it comes into the topcase funny things happens. I will find a new topcase amd voila … should work. Sorry for all the “concerns” and Thank you again. All fine now

 

[2informaticos]

When you have the board placed on the chassis, disconnect the cables, one by on.
Check which connection blocks the backlight.