Character LCD on/off and lifespan

**bombboyer** · 09-23-2002, 10:45 PM

What's the average lifespan of a 40x4 character LCD? I'm wondering if it would be better to turn it off if I'm listening to the radio. How could I rig an on/off switch to the LCD without damaging my power supply, as I use a molex to get the +5 from my power supply (AC/DC)? I want to turn off the actual screen, not the backlight or the contrast all the way down.

**Charliey** · 09-23-2002, 10:58 PM

I think the life should be pretty good, and out of everything, id only worry about shutting off the back light.

Just solder a little switch into the line thats feeding power to the back light.

**bombboyer** · 09-25-2002, 08:49 PM

Originally posted by Charliey

Just solder a little switch into the line thats feeding power to the back light.

I don't think that will work, as I think it will blow a PS if you plug/unplug things with the computer on. Any other ideas?

**MP3DUB** · 09-25-2002, 11:22 PM

You shouldn't have to wory about the lifespan of your lcd, as most of their mtbf are quite long (think lcd clocks in early 80's cars).

**Charliey** · 09-28-2002, 12:04 AM

If youre only turning on/off back light, it should be alright.

The problem occurs is when you accidently short the power supply wires when your computer is running. Then it restarts.

The other problem that can happen is its not good for the LCD processor when there is a signal applied to the data pins (ie it is plugged into the parallel port), but it does not have power supplied to the power supply pins.

So, only install a switch to turn off the back light, not the main power to the screen, unless you remove the parallel connection with it.

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