Hello
It is extremely important for a factory that I test this display
The display was mounted into a very old machine
The company that made the machines is no longer in business.
I'm not a certified technician I'm just a hobbyist and the machine is from my parents factory.
No one in here (Venezuela) is willing to look at the machine without the electronics blueprints which are of course non existent since again the machine is VERY old and the company is out of business.
I got a 10k Resistor between 5v and GND
Also I got a 10k Pot one ent at VCC the other at GND the middle goes to LCD pin 3
LCD Protoboard Arduino
1 GND GND
2 5V 5V
3 MIDDLE OF POT
4 12
5 GND
6 11
7 NC
8 NC
9 NC
10 NC
11 5
12 4
13 3
14 2
The display doesn't even turn on but i'm sure at least it turns on
I'm trying to run a modified hello world from the LCD library
I just changed the line from lcd.begin(16, 2); to lcd.begin(40, 2);
Many thanks
DMC-40218 73-1069-datasheetz.pdf (165 KB)
The first thing you should do is make sure that the display 'works'. To do this you do not need your Arduino except possibly as a voltage source.
Connect your power to pins 1 and 2 and connect the potentiometer to pin 3 as you have described above. With the potentiometer set to one end the display should be blank and at the other end you should see rectangles or blocks at each character location on the top line and maybe also on the bottom line. The correct setting is where the top line of blocks is barely visible.
If you don't see the blocks then you may have an extended temperature range device which requires a negative voltage (with respect to GND) on pin 3. To check this out you will need another power supply, a 9-volt battery will suffice. Connect the POSITIVE terminal of the battery to GND. Disconnect the end of your potentiometer from GND and connect it instead to the NEGATIVE terminal of the battery.
With this arrangement you can adjust the voltage at pin 3 from +5v to -9v (with respect to GND) and you should, at some point, see the rectangular blocks.
If this works you can hook up the other six connections to the Arduino and the GND at LCD pin 5 and you should see your message on the display.
Don
Dear Don
Thank you So much!! For letting me know and taking the time to answer me.
As you can see a very expensive machine old bus still functional can't be put to work because of this.
I was hoping that you could answer me since you and the Brazilian guy were the only ones I could find in here that have posted about that LCD
The thing is that the display does not turn on either regular way
and if I put the battery as you describe and turn the potentiometer I just see 2 small vertical lines in about 1/3 of the LCD like | |
and after like half a second it fades
It doesn't matter every time I turn clockwise or counterclockwise the potentiometer lines appear but quickly fade. I can not se solid block at all.
Does it means my display is bad?
If so can it be substituted by a regular 40*2 display that uses HD44780 or you advice to look and buy the same old display?
Thank for your reply again
Belen
Dear Don
Thank you So much!! For letting me know and taking the time to answer me.
As you can see a very expensive machine old bus still functional can't be put to work because of this.
I was hoping that you could answer me since you and the Brazilian guy were the only ones I could find in here that have posted about that LCD
The thing is that the display does not turn on either regular way
and if I put the battery as you describe and turn the potentiometer I just see 2 small vertical lines in about 1/3 of the LCD like | |
and after like half a second it fades
It doesn't matter every time I turn clockwise or counterclockwise the potentiometer lines appear but quickly fade. I can not see solid block at all.
Also something is really really weird. If I do not supply any power to between Pin 1 (GND) and pind 2 VCC (Power supply for Logic) and disconnect for a second the POSITIVE side of the battery (mantaining all connections) for a quick time, then I can see solid blosk in random parts of the display but not all across it.
Does it means my display is bad?
If so can it be substituted by a regular 40*2 display that uses HD44780 or you advice to look and buy the same old display?
Thank for your reply again
Belen
Dear Don
I have replied to this with my tests results
You available or anyone else who can also point me out in the right direction?
Many thanks
