Toshiba Satellite L500-1R1 no backlight

[rtstorm]

Hi,
i have this toshiba, when turn ON, all working ok but no backlight on LCD.
I disassemble the screen and i think this is LED LCD so no inverter.

Can you please check the photo of the LCD board and tell me what should i check.

I see on one pict there is circle component marking (220). Is this a capacitor?

Thank you

[dycc]

Re: Toshiba Satellite L500-1R1 no backlight

Pin 1 ,2,3=19v (VSL)
pin 5=3.3v (BL_EN)
pin6= 3.3v for full brigthness (PTW)

[rtstorm]

Re: Toshiba Satellite L500-1R1 no backlight

pin 1= 0V
pin 2,3 =3V
pin 4,5,6 =3.15

[rtstorm]

Re: Toshiba Satellite L500-1R1 no backlight

I think i dont have anyware 19V on JLVDS connectror on mainboard.

Here is schematic

[rtstorm]

Re: Toshiba Satellite L500-1R1 no backlight

i found 19V on LCD board, it is marked here.

[dycc]

Re: Toshiba Satellite L500-1R1 no backlight

0.81v is too small for back light control . it should be between 2 and 3v max . reflow GPU and if it does not not work ; disconnects the connector pin(0.81v) and with a wire ,solder 3V(+v3alw) directly from the motherboard up to the screen at pin ptw(0.81v).

[dycc]

Re: Toshiba Satellite L500-1R1 no backlight

it'll work, but it may display blank screen before the writing appears. minor annoyance but it does not prevent the laptop to operate

[rtstorm]

Re: Toshiba Satellite L500-1R1 no backlight

But i can see the picture on display only backlight is not working, is this really issue with GPU?

[dycc]

Re: Toshiba Satellite L500-1R1 no backlight

yes because GPU trigger the switch who give brightness

[dycc]

Re: Toshiba Satellite L500-1R1 no backlight

according to your diagram you have to disconnect pin 11(JLVDS) on page 18 . solder +3VALWP(page 40) on it and you will see the magic .

[rtstorm]

Re: Toshiba Satellite L500-1R1 no backlight

Hmm how to disconnect pin 11? Any suggestion so I do not break that pin.

But i noticed that i dont have anymore picture on LCD, only on VGA output. I check Fuses and noticed that fuse is dead, i dont know how but it is not pass contingency test.

What value is that fuse?

[rtstorm]

Re: Toshiba Satellite L500-1R1 no backlight

i got pictiure on LCD, still no backlight. i will try to connect +3VALWP (page 40).

But i am not shure how to disconnect pin 11(JLVDS)

[rtstorm]

Re: Toshiba Satellite L500-1R1 no backlight

is it necessary to disconnect pin 11 on JLVDS? can i just connect +3VALWP directly on pin 11 JLVDS?

[alihomee]

Re: Toshiba Satellite L500-1R1 no backlight

did you try with other led and cable?

[rtstorm]

Re: Toshiba Satellite L500-1R1 no backlight

No i dont have another led this type

[spleenharvester]

Re: Toshiba Satellite L500-1R1 no backlight

Maybe you could break Pin 11 off on the cable side? I'm not too sure.

[rtstorm]

Re: Toshiba Satellite L500-1R1 no backlight

hmm ok, i will try that way.

[rievax_60]

Re: Toshiba Satellite L500-1R1 no backlight

I first try to apply the voltage through a resistor to avoid causing more damage.
470 ohm to 1k should be ok.

[spidey]

Re: Toshiba Satellite L500-1R1 no backlight

i think you have problem with your led control ic or led itself. Check the working conditions of ic, in the 2nd photo near the ribbon cable which goes to leds.

[rtstorm]

Re: Toshiba Satellite L500-1R1 no backlight

i disconnect pin11 and connect +3VALWP on it, but light wont turn on. Now i have 3V on PWM. Is this the LCD screen fail?

@spidey: how can i check this IC?