LCD backlight problem

UltraMan · 11-09-2001, 04:39 PM

I was out in my truck cutting a hole for the 16x2 crystalfonts lcd in my dash, and when i finished i turned the computer on, and the lcd was working fine. The backlight started to dim and then went completly out. I have no idea what the problem is, but it is the second time its happened. I dont think it shorted out, and i'm pretty sure all the connections are good. Could it be a bad potentiometer? What kinds of things cause a backlight to break or stop working? Thanks.

moahdib · 11-09-2001, 10:41 PM

how is it powered? if it's by your power supply it might not be able to supply enough current to power your LCD....
in that case just use a 7805 voltage regulator with a heatsink...you can take 12V from your battery and it will supply 5V 1A max.

UltraMan · 11-10-2001, 10:39 AM

It is powered by my power supply in the comp, but i think i just had the potentiometer set to 0 resistance and burnt out the backlight. Is there a way to figure out what kind of resistance would be optimal for the backlight? thanks

SuperMatty · 11-10-2001, 09:54 PM

I think its unlikely not having the potentiometer set above 0 ohms fried it. I have connected my backlight on my LCD like this numerous times. However, I don't have the model that you have so I suppose you may be correct in assuming that. Generally, the manufacturer will specify how much resistance should be applied to the backlight. In my case, according to Densitron, 2.3 ohms was recommended. Generally, if the optimum resistance is applied, the backlight will be bright, but will not get very warm until after a long period of time.