I'm new to electronics and I'm trying to figure out if it is dead or not. Here is the product in question: http://www.sparkfun.com/commerce/product_info.php?products_id=256 I have tested the back light and it works. I don't have a potentiometer for the contrast lead, but I figured that I could use a 10k resistor instead. I don't know whether it should be connected to + or -.
I've tried this: LiquidCrystal - Arduino Reference and wired it accordingly. I'm not able to get the LCD to do anything. Any ideas on how I can verify that it is not dead?
When I first tried my 1st LCD panel I failed miserably.
The contrast control is very important. Using a pot, you will find that you only see a picture on the screen at a specific setting. I found some small 20-turn pots in an old VCR. It made a big difference.
The picture shows a 20k pot. It also shows that it is exactly across + and - which means it is a short. But the resistance is high enough not to cause problems with heat or battery. That means you can go higher but do not go too far lower (even a 10k would work). I have also used 50k and 100k pots in a pinch since I had them in my junk box.
Go to google images and look for a 20-TURN POT for some pictures of what they look like. VCRs are filled with pots. Find a dead VCR and steal the caps and pots.
The pot is being used as a voltage divider. The pot setting determines what the LCD panel sees for contrast voltage.
When the pot is adjusted all the way CCW you will get 0V (in series with 0ohm) connected
to VLCD. When the pot is adjusted all the CW you will get +5V (in series with 0ohm)
connected to VLCD.
If you short GND (0V) to VLCD you get one constrast level. Shorting +5V to VLCD
you get the opposite constrast level.