No backlight on LCD - 820-3437 Macbook Air

[patrickribbsaeter]

check if you get an image or backlight. if you still dont get an image either an apple logo or flashing folder by flashing light onto the apple logo on the back of the screen then check continuity on pin 18/19 of lvds connector and pin 2 of L8304 and check voltages on pin 18/19 of lvds as well.

- LVDS connector Pin 18/19 i get on both 000.2v (schematic says should be 3.3v) (in continuity mode I get: OL. on both pins 18/19. NO BEEP!
- pin 2 of L830: I get NO beep in continuity mode. and voltage I get the same 000.2v
- pin 1 of L830: also shows 000.2v and NO beep!

 

[patrickribbsaeter]

What about U8300...? Could that be a problem?

 

[Gmorb]

I always let my iron go up to 750 honestly.

 

[patrickribbsaeter]

I always let my iron go up to 750 honestly.

Thats farenheit right, not celcius..? I have 450 celcius on mine.

 

[Gmorb]

As long as it works for you and its not taking forever to melt solder youre fine at that temp.

 

[JohnB8812]

Lets start over...Do you have 3.3 volts on pin 18/19 of the LCD connector? If so, you should have image meaning if your screen doesn’t have image, try another known good test screen. If you DON’T have 3.3 volts on pin 18/19, check to see if it makes its way to L8304 pin 1. If yes, possibly blown inductor or bad trace from inductor to screen. If NOT getting voltage on pin 1, check if EDP_PANEL_PWR is present at pin 1 of U8300

 

[patrickribbsaeter]

Lets start over...Do you have 3.3 volts on pin 18/19 of the LCD connector? If so, you should have image meaning if your screen doesn’t have image, try another known good test screen. If you DON’T have 3.3 volts on pin 18/19, check to see if it makes its way to L8304 pin 1. If yes, possibly blown inductor or bad trace from inductor to screen. If NOT getting voltage on pin 1, check if EDP_PANEL_PWR is present at pin 1 of U8300

Thanks. Im going to check exactly what u described and get back to you here shortly.. meantime.. Do you know if this Backlightdriver works for this motherboard? https://www.mouser.se/ProductDetail...=sGAEpiMZZMsE420DPIasPlogyTiw5Lxrbcr5vzVG7Qo=

 

[JohnB8812]

Possibly. I recommend buying them from store.rossmanngroup.com Don't delay buy today!

 

[patrickribbsaeter]

Possibly. I recommend buying them from store.rossmanngroup.com Don't delay buy today!

yes, make it easy.. DONT DELAY, buy today

 

[turbo]

1. No apple logo when adding light to the screen. The screen is pitch black still.
2. I get chime when pushing start button. And the apple logo on the back of the LCD is lit. But not front.
3. L7701 (I have 8,5 Voltage). On Diode mode I have 0.384.
4. C7710 (resistance mode I get 0.428) and Voltage mode 5.12V)

change led driver