Interfacting 4x40 HDD780 LCD with Printer port (Parallel Port)

**Fosgate** · 02-03-2002, 06:32 PM

Dude the number on the right are not the parallel port pins... its the pins of the standard 4x40 LCD screen another words you need a schematic on how to connect standard 4x40 LCD screen to parallel port and where ever you see the pins numbers for the standart LCD use the ones that i posted above instead... You know what ... It probably would be easier if i give you the pin outs for the parallel port instead of the standard LCD. Will try to do that tonight.
As for 100V its basically the output of your backlight inverter... you going to need one.
and for -2.5v that will be bit complicated... you might need to use Maxim chips to get that voltage or make a circut that will convert -5v from your computers supply to -2.5v

**Jarrod** · 02-03-2002, 08:35 PM

I'm goin to need a backlight inverter? What for? Where do I get one appropriate for my LCD in Australia? Any help on a circuit to get -2.5V from -5V input would be greatly appreciated.

**MP3IAN by Ian Gregory** · 02-03-2002, 11:05 PM

Good to see you also own a VL Berlina and are having exactly the same trouble as me!!!!
Bloody things! I used the schematic as mentioned before and i receive the two rows of blocks upon startup but i don't get any response by using lcdprint or lcdisplayer etc.

**Rob** · 02-04-2002, 02:50 PM

Any help on a circuit to get -2.5V from -5V input would be greatly appreciated.[/QB]

There is a chip called an LM337T

I hope this is of some use.

Rob

**Jarrod** · 02-04-2002, 08:19 PM

The info on that chip says its adjustable from -1.2V to 30 something volts, which means it cannot go down to -2.5V which I require. Also, what voltage does it require to begin with?

**Ces///M3** · 02-04-2002, 08:30 PM

where can i purchase one of these 4x40 el drivers? thanks

**Jarrod** · 02-05-2002, 11:17 PM

I got the 40x4 EL LCD from www.rockby.com.au

here is a link to one inverter I found: http://www.allelectronics.com/spec/BXA-12529.pdf but it seems it doesn output 100V AC, actually, nowhere near it, it outputs 750 V AC or sumfen, so where the hell am I meant to find one that outputs 100V AC X 2 (two backlights) from 12V DC input?

**Miel Gibson** · 02-06-2002, 12:30 AM

Sure you can use an LM337T, it's adjustable from - 1.2 to -37 volts with a maximun input of - 4.2 volts. Go hereto get the circuit
I went to that web site where you got the LCD from and I couldn't find any LCD with backlight, which model did you get?

[ 02-06-2002: Message edited by: Miel Gibson ]

[ 02-06-2002: Message edited by: Miel Gibson ]

**Jarrod** · 02-06-2002, 03:24 AM

The model I got isn't listed in their 'online' catalogue, i hade to ring them up and they had one in stock.

Need any other info about the LCD for you to be able to help me?