(SOLVED) LCD technical difficulties

Hi, I have 2 LCD's. One of my LCD's is a 20x4 2004A with I2C and the other is a 16x2 QAPASS with I2C LCD. Both of my LCD's will not work consistently and i will need to wiggle around some wires to try and help the connection but they are very inconsistent. They work at times then stop working a little later. Is it the LCD manufacturing? the wires connection? or is it something else?

Have you soldered the connections to the LCD module?
Show photos of your devices and the soldering used on the connections to them.

--- bill

I only have the I2C modules soldered to the LCD’s. The wires used to connect the I2C to the arduino are not soldered. Here are the pictures.

Here is the second file

how about the other side of the LCD module, where the pins are soldered to the LCD module?
Can you show a photo of that?

If the soldering is good on that side, then it could be the pin connections on the Arduino.
Some Ardiuno boards have headers that have internal metal connections that are not very tight and if you have pins on your wires that are narrow (some pins are thinner than others), it can make a combination where the connection is not very good and can have issues.

If you want to test the i2c signals and the internal LCD RAM, you can use the hd44780 library and run the run the included I2CexpDiag diagnostic test.
The hd44780 library is available in the IDE library manager.
You will want to use examples in the hd44780_I2Cexp i/o class.
Additional documentation can be found in the included Documentation example sketch.
It has information and many links to additional information.
There is also additional information about the library on its gitub page and wiki.

--- bill

Are you using a tie point breadboard?

I am not using a tie point breadboard. Here is the other side of the LCD.

I am having trouble putting the picture

Are you using a tie point breadboard?

Look at the photos posted. You can see how everything is wired up.

--- bill

I am having trouble putting the picture

You may be trying to post a photo that is too large or you may be out of attachment space.
This forum enforces some silly size limits for attachments.
One is a 2MB file limit. (this one is ok for photo attachments since photos should not need to be that large)
You can definitely make the photo a lower resolution than the prior photos.
However, you also may have to go back and shrink the photo sizes that you previously posted to free up some space in your limit as I think that there is also some kind of maximum total size limit for all your attachments.

--- bill

OK, here we go:



here is the other side of the LCD’s where the I2C is soldered to the LCD’s

OP image.

Solder looks ok.
There may be an issue with the wires and connectors.

Once it is working, if you don't move it or touch it will it continue to work?

Have you run the I2CexpDiag example sketch that comes with the hd44780 library to see if it detects any issues?

--- bill

I could not find the example I2CexpDiag

There might be another problem. The LCD I2C's power LED is not turning on when connected to the arduino when the arduino is on.

The LCD I2C's power LED is not turning on when connected to the arduino when the arduino is on.

That is a problem.
The i2c backpack power led should be on whenever there is power.
If it is not on, there is a power issue.
It is more than likely do to a bad connection in the power or ground wire.
It could be the connector at either end or the wire itself.

It could also be short in the wiring or connectors.
If it is a short, then the power led on the Arduino would also go off as the USB fuse turns off the power from too much current draw.

--- bill

The led on the arduino is on and is not turning off. I will try to use other new wires and see if that fixes the problem.

The problem has been fixed. I just switched to other new female to male wires and all worked perfectly. Thank you anyway for your help.

Usual problem.

As soon as you have anything not working as you suppose it should, test all "Dupont" jumper wires.

A lot that have been sold over time, are not even proper copper wire - apparently copper plated aluminium which cannot be soldered and may even cause problems with crimped connections. :astonished:

You don't even get what you paid for! Sad that we are sold rubbish but - that's what the world is like. :roll_eyes: