Dell inspiron N7110 LCD no back light

[bigsam731]

Re: Dell inspiron N7110 LCD no back light

OK. Ill hold off on it and use it as is for now till Mr. Budm can figure something out. Please let me know if you need me to do more testing or anything else. I really appreciate you guys help.

[meritosari]

Re: Dell inspiron N7110 LCD no back light

I believe this case will end with Happy ending.

[budm]

Re: Dell inspiron N7110 LCD no back light

OK. Ill hold off on it and use it as is for now till Mr. Budm can figure something out. Please let me know if you need me to do more testing or anything else. I really appreciate you guys help.

Please see post 40.

[bigsam731]

Re: Dell inspiron N7110 LCD no back light

I did disconnect the wire going back to pin 18 from pin 36. I just connected it to pin 2 without a resistor. what does S3, on pg. 2 of the schematics, have to do with LCDVCC?

[budm]

Re: Dell inspiron N7110 LCD no back light

That page is not truely clear to me if the S* STATESare the sequencing of the power or what.
I would suggest to use resistor between pin 2 and pin 36, when pin 2 3.3VDC is switched off then the backlights will be off at the same time, and when the pin 2 is switched on then you will have backlights. So basically we are using the switched pin 2 3.3V to turn on and off the backlights.
You can verify that pin 2 is a switched power by checking to see if 3.3V is NOT present when PC is off.

[bigsam731]

Re: Dell inspiron N7110 LCD no back light

I will double check and make sure that pin 2 has switched power. Laptop should be plugged into power or the battery and in the off state when I do the test correct?

Also, why do I need a resistor between the two pins? And what type of resister should I use? Please forgive my ignorance on the last two questions, I just want to learn.

[budm]

Re: Dell inspiron N7110 LCD no back light

I will double check and make sure that pin 2 has switched power. Laptop should be plugged into power or the battery and in the off state when I do the test correct?

Also, why do I need a resistor between the two pins? And what type of resister should I use? Please forgive my ignorance on the last two questions, I just want to learn.

'make sure that pin 2 has switched power. Laptop should be plugged into power or the battery and in the off state when I do the test correct?' Correct.
The resistor is in the circuit to limit the current in case there shorted circuit between pin 36 and GND when something goes wrong.
470 Ohms 1/8W or 1/4W will do.

[bigsam731]

Re: Dell inspiron N7110 LCD no back light

Pin 2 is switched. I checked the voltage while the laptop in in the off state and got 2.1MV. and will install the resistor once I receive the order.