# LMB204BFC 20x4 LCD problem

#### walid el masry

Joined Mar 31, 2009
132
i have LMB204BFC 20x4 LCD since long time ago and i can't remember if i break it mistakenly but when i tried to use it again i noticed that 1st 8 characters of rows 1&2 is not working properly and i don't know why, so i hope anyone can help me !!!

a description to my problem is in this video

#### spinnaker

Joined Oct 29, 2009
7,835
Check your contrast pin. Do you have a resistor or better a potentiometer on contrast?

Check you initialization code. Do you know it has worked before?

Step through your code, use a scope or logic probe and verify commands and data are getting to the LCD the way you think they are getting there.

#### walid el masry

Joined Mar 31, 2009
132
everything about the hardware and software is ok, it not the 1st time i use LCD but its just weird that i lost the 1st 8 characters when i reach the 3rd row it just annoying they work way and not in another so i hope if the is explanation to this and if it is an internal hardware defect

#### spinnaker

Joined Oct 29, 2009
7,835
Well if everything is OK then why is it not working? Obviously you have a problem somewhere. You also could simply have a bad LCD.

And could you please use capital letters to start a sentence and a period to end one? Otherwise it is really annoying to read.

#### walid el masry

Joined Mar 31, 2009
132
Well, am sorry if i annoyed you!.

#### spinnaker

Joined Oct 29, 2009
7,835
Well, am sorry if i annoyed you!.

I didn't say you annoyed me, I was just pointing out that it is only common courtesy to make your posts as readable as possible.

#### walid el masry

Joined Mar 31, 2009
132
Ok thanks, i will buy another one they cost about 10$here, i just wanted to know if there are any explanation to this but sounds like its a hardware defect due to something i didn't noticed. Thanks again. #### spinnaker Joined Oct 29, 2009 7,835 Ok thanks, i will buy another one they cost about 10$ here, i just wanted to know if there are any explanation to this but sounds like its a hardware defect due to something i didn't noticed.

Thanks again.
Yeah I have blown out about a half dozen of them and have seen similar
behavior.

The white boxes are usually a hint of contrast problems but the strange jumping around like that usually means a bad device assuming everything else is OK.

The video was a good idea.

I like to try and put headers on all of my LCDs. Make them all the same for each project. So what I did was to build an LCD tester. I can simply plug
in an LCD and test it if I suspect it is bad.

You are living in Egypt now? Is it still easy to get product with all that is going on? \$10 US is a pretty decent deal if it is a local purchase.

I can't do that well here if you throw in shipping. I don't know of anywhere within several hours drive that might carry anything like that. Pretty sad as we used to have at least two electronic distributors in the city along with one other that sold surplus gear. They are long gone.