lcd test

i have removed a LCD out of a HP printer (hp1000) its a 14pin is there a way to test its pinout ,, its easy enought to test for ground pin but thats about it, Cant realy see and visiable part numbers i still have the board it was on . wasnt able to find any simple referances to just the lcd,,, and thoughts :) ? i think its a non-backlight lcd do to the fact of only 14 pins. the 3rd pin in is the ground so it doesnt seem to conform to a normal pinout set.

the 3rd pin in is the ground so it doesnt seem to conform to a normal pinout set.

Some displays work well with pin 3 grounded so this device could have the standard 14-pin pinout.

Don

so do you think it is just the ground and Vin are just swithced? i have seen a section someplace with a different pinout for LCDs but of course now i cant find it :) ill have to track it down again. i thought it was under the LCDs library.

so do you think it is just the ground and Vin are just swithced?

That's not what I said. There is a (subtle) difference between pin 3 being grounded and pin 3 being the ground.

Normally there is a potentiometer whose ends are connected to +5V (typically pin 2) and GND (typically pin 1). The wiper of the potentiometer goes to pin 3. Most displays work best when the wiper is close to the ground end of the potentiometer putting around 0.5 V on pin 3. Some displays work satisfactorily with the wiper all the way at the end which effectively connects pin 3 to ground. When that is the case you really don't need the potentiometer, just connect pin 3 to ground.

So the real question is: can you find another pin that is "GND". This will typically be pin 1, but it is sometimes (rarely) pin 2.

More questions: Are the 14 pins in a single row or in two rows of 7 pins? If they are in a single row then where is that row with respect to the display? Most displays have the single row of pins at the upper left or the lower right. In either case pin 1 is typically near the edge of the board. If the pins are at the lower left then they are typically numbered with pin 3 near the edge then 4, 5, 6, ..., 14, 1, 2 as you go toward the center.

Don

Can you post a couple pictures of the display? I'm only guessing this display is HD44780 compatible. At the moment, I'm compiling a list of displays you can easily salvage with the following and this thread could help me with this list and help future people salvaging displays:

| Host device | Display type | Pin-out | OP | Pictures | | - | - | - | - | - | | HP1000 printer | HD44780 w/back light(?) | Standard(?) | http://arduino.cc/forum/index.php/topic,95093.0.html | N/A |

This list post is here if you're interested in helping:

http://arduino.cc/forum/index.php/topic,95196.0.html

this display has a single row of a ribbon cable and of course there centered :) . I'll post some img shortly :)

Here ya are ,, hope this helps :) https://picasaweb.google.com/110333204650769760273/LCDDisplay?authuser=0&feat=directlink Also third from the right was the same as Case ground.

My instinct tell me, this display is just an LCD. That it. The control circuit is on the board where that LCD is connected. Unless it has a circuit under that LCD, if not, well you are out-of-luck, unless you hack that board.

My 2 cent.

lol excesive hacking for a inexpensive part ,,, probably not worth the effort :)

woody_unreal: lol excesive hacking for a inexpensive part ,,, probably not worth the effort :)

You are missing the fun part ...of hacking <--> thinkering ;)

Correct - i love to tinker ,,,, but i have already ran down most of the ICs from the board, it doesnt seem to be one of those popular boards that have alot of datasheets, lol so i have took apart somemore stuff :) Well See about this one MC1604c-syl its a 4x16... once again i have created more work for myself :)

Thanks for the picture. Unless we know what sits on the back side of that glass, we can never tell. I am still leaning towards LCD+control circuitry. Since a bare LC glass would have way more connections than that ribbon cable. There's still hope.

To hack, is to reversed engineer, to thinker, to do live tests and see what happen. <--- that is the fun part. :grin:

Let hope no magic smoke happen. :roll_eyes:

The hope is : look for a + V line <-- A Vcc , and GND line if it fit the standard LCD pinouts. And check for data lines and possible control line.

About the chips numbers. Google it. You may fine something of interests.