LCD Good or Bad

I recently picked up two Displaytech 204A LCD panels from a control panel. But I don't know if they are working or not. I took one of them and connected as described on one of the threads on this forum. But I did not get any display at all. The spec sheet says the backlight uses 3.3V so I connected it to the arduino 3.3 V (pin 15) and 16 to ground. Pins 1 and 2 to 5V and ground respectively and pin 3 to the wiper of a 10k pot with the other two pot leads to gnd and 5V.

Still nothing at all. I checked voltages and they are all OK, then I thought maybe a short between pins on the LCD, so checked that and they are all OK.

So I am out of ideas to try and find out whether or not this LCD is even any good or should I just deep six it.

Thanks.

Hi,
Find attached the display specs and pinouts.

Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?

Can you post the code you used please?

Thanks... Tom.. :slight_smile:

204A series-v21.pdf (1.25 MB)

TomGeorge:
Hi,
Find attached the display specs and pinouts.

Yes, I read this. Thanks.

Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?

Can you post the code you used please?

I didn't use an code yet, I just connected pins 1, 2,3 and 15 and 16. Pin 1 to 5V pin 2 to gnd, pin 3 to the wiper on a pot with the other two pot wires to gnd and 5V. Pin 15 to 3.3V and pin 16 to gnd. That should give me some indication that its working. Basically what I expected was dark squares on a light background with the pot giving me the ability to adjust the contrast. But there is absolutely nothing on the screen. I have power to the lcd, I tested the pins and can read the voltages and they are what they should be. I can take a picture of the wiring but it looks like this: https://301o583r8shhildde3s0vcnh-wpengine.netdna-ssl.com/wp-content/uploads/2014/11/LCDpot-min-1.jpg except I connect 15 to 3.3V from Arduino.

Thanks... Tom.. :slight_smile:

I also found this document which gives me the pin outs. Interesting that there is no voltage specified for pins 15 and 16. http://docs-europe.electrocomponents.com/webdocs/06dd/0900766b806dda1c.pdf

"All" my LCD displays were "broken"......

Then I discovered the POT trimmer...now they ALL work :slight_smile:

Hi,

I didn't use an code yet, I

Well you will only know if you connect to your controller and run some code.
OPs image.

You will need to connect a lot more than that, the display controller has not been sent any display commands.

Tom... :slight_smile:

TomGeorge:
Hi,

Well you will only know if you connect to your controller and run some code.
OPs image.

You will need to connect a lot more than that, the display controller has not been sent any display commands.

Tom... :slight_smile:

TomGeorge:
I was under the impression that this connection would give me a background with brightness/contrast that can be adjusted by the pot. I'll play some more and see what turns up.
Hi,

Well you will only know if you connect to your controller and run some code.
OPs image.

You will need to connect a lot more than that, the display controller has not been sent any display commands.

Tom... :slight_smile:

quamikazee:
"All" my LCD displays were "broken"......

Then I discovered the POT trimmer...now they ALL work :slight_smile:

Pot trimmer?

Hi,
Can you post some pictures of your displays, front and back?

Thanks.. Tom.. :slight_smile:

TomGeorge:
Hi,
Can you post some pictures of your displays, front and back?

Thanks.. Tom.. :slight_smile:

I have no idea how to upload photos to this forum. sorry.

Here are two photos of the LCD

Here are two photos of the LCD

Hi
You need to attach them.
Please read
http://forum.arduino.cc/index.php/topic,148850.0.html

You can scroll down to image instructions.

Thanks. Tom.. :slight_smile:

TomGeorge:
Hi
You need to attach them.
Please read
http://forum.arduino.cc/index.php/topic,148850.0.html

You can scroll down to image instructions.

Thanks. Tom.. :slight_smile:

Tom,
Tried that but got an error message. So must be a problem with the images. But I have another 4 X 20 that I salvaged, Its a Lumex SO2004 D. The spec sheet (http://datasheet.octopart.com/LCM-S02004DSR-D-YE-Lumex-datasheet-21629521.pdf) doesn't show anything for pins 15 and 16. Does that mean there is no connection to these two pins. The DisplayTech I was originally working with required 3.3 V for the back lighting on those two pins. But I supposed they are all different. I am a real novice at this soo......

ov10fac:
Tom,
Tried that but got an error message. So must be a problem with the images. But I have another 4 X 20 that I salvaged, Its a Lumex SO2004 D. The spec sheet (http://datasheet.octopart.com/LCM-S02004DSR-D-YE-Lumex-datasheet-21629521.pdf) doesn't show anything for pins 15 and 16. Does that mean there is no connection to these two pins. The DisplayTech I was originally working with required 3.3 V for the back lighting on those two pins. But I supposed they are all different. I am a real novice at this soo......

Sounds like it doesn't have a backlight.
Make sure your images are under 1M, resize in a graphics program, I use Paint, Win7.
jpg, png are best.
Tom... :slight_smile: