I just attempted my first project with an LCD, and it did not go well. I am hoping to get some advice on how to prevent this from happening to my next LCD.
On the first night everything seemed to work fine - the LCD was bright and clear. On the 2nd night I suddenly noticed smoke coming from the backlight LED+ pin (pin 15).
I measured the current going through the backlight and it was something like 80mA. Seems very high to me...
I examined the other side and could see melted plastic:
The datasheet says that no resistor is necessary for the backlight, but I tried hooking up a 12 ohm resistor anyways. This stopped the smoke, but caused the backlight to flicker. I found another datasheet for a similar LCD, and that one required 4.2V instead of 5V on the LED. I tried doing that as well by hooking up the LED through two diodes in series, but this setup continued to smoke. I measured the current again, and now it was drawing 600mA! I am currently running the LCD w/o the backlight, since it now starts making a boiling sound immediately when I connect it.
I have purchased this LCD here: http://www.adafruit.com/products/181 http://www.adafruit.com/datasheets/TC1602A-01T.pdf
And hooked up the backlight in accordance with this tutorial: http://learn.adafruit.com/character-lcds/wiring-a-character-lcd
Note that both the tutorial and the datasheet hook up the LED directly to +5V, which is exactly what I did.
So, what could have gone wrong? What precautions can I take to prevent this from happening again? Any suggestions would be appreciated!
Here is a video that shows a bit more of the setup and the smoke: http://www.youtube.com/watch?v=Wdqyi4hqlMw