Quote Originally Posted by RYTECH
The lcd datasheet doesnt say much about anything.

i metered the lcd backlight - 50 milliamps

The only other things powered off the 7805 is the LCD itself, a pic 16F84a.

The current rating is 1amp on the 7805, no heatsink is attached.

Input voltage is between 12 and 18v. When the LCD backlight is unattached, the 7805 remains cool, the circuit and lcd function normally.
I think you need to add a heatsink. Your regulator is dropping upto 13V with worst case supply voltage. At 50mA the LCD will be causing it to disipate an additional 0.65W with only the tab to get rid of the heat.

The 7805 datasheet I have just looked at says that maximum power dissipation is "Internally Limited" so it *shouldnt* self destruct but best not risk it

What is the TOTAL current you are drawing from the supply.