LCD2041-WB-V Backlight

Tw1tch · Post by **Tw1tch** » Tue Oct 22, 2002 9:31 am

Hi,

I brought this issue up on the lcdc boards first but it seems to be more a hardware problem more than a software one.

I set up hotkeys via lcdc but can't seem to toggle the backlight on/off with it. I also tried the AlphaDemo and the program couldn't toggle the lcd backlight either. Everything else works beautifully including the hot keys I set up to go forward and backward through the different screens. Anyone have any ideas to what is causing this?

I also tried Matt's suggestion of using the test area in lcdc but the backlight toggle doesn't work either. I tried other commands such as clear screen and cursor home. All of them worked with the exception of the backlight on/off commands. I also rechecked the connections and thay all seemed snug.

I can live without this feature (considering everything else works) but was wondering what is causing it not to work.

Thanks in advance.

Miles · Post by **Miles** » Tue Oct 22, 2002 1:27 pm

When power is applied to the unit, is the backlight already on and you can't turn it off?

Tw1tch · Post by **Tw1tch** » Tue Oct 22, 2002 2:25 pm

Yes, the backlight is already on when I first start the unit.

Miles · Post by **Miles** » Tue Oct 22, 2002 2:36 pm

Do you have access to a multimeter?

Tw1tch · Post by **Tw1tch** » Tue Oct 22, 2002 2:45 pm

No but I can go after work and get a fairly cheap one. It will probably come in handy for other uses.

Miles · Post by **Miles** » Tue Oct 22, 2002 2:52 pm

Let me know ASAP and we can do some measurements!!!

Tw1tch · Post by **Tw1tch** » Tue Oct 22, 2002 5:42 pm

Just got back from the store. Sorry I'm very new to this. What should I measure and how?

SiGmA_X · Post by **SiGmA_X** » Tue Oct 22, 2002 6:36 pm

I have the same problem, same LCD too... Please post instruction soon! (I have a multi-meter already

)

Thx.

Miles · Post by **Miles** » Wed Oct 23, 2002 2:03 pm

We are going to measure voltage so you need to apply power to your LCD. Set your multimeter to 20 Volts DCV.

1) Place the ground pin of your multimeter (black) in on of the holes next to the voltage regulator (component next and a little above the power connector, part#78M05).

2) Place the positive pin of your multimeter (red) on the data pin that controls the backlight. This is located on the gate of the N-channel mode field effect transistor. The part # is a 6Z. This is located above the 7660 in the upper left corner of the PCB.

3) Your next step is to measure the voltage while the backlight is on and then by using your software turn the backlight off and take a measurement.

Let me know your results!!