Weird characters on CFAH2002A

[Neily]

We have had 3 of these lcds fail in this manner out of about 75 units. The one in the picture was running fine for weeks. I went for lunch, and when I came back it was messed up. Anyone seen this problem before?. Power off/on does not fix it. Its being controlled with a freescale MC9S08GB60 in 4 bit mode using my own software. I don't suspect software or timing issues because its a rare problem, and once it shows up it can't be fixed.

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[CF Tech]

That is an odd failure.

It looks like some how the CGROM has been corrupted--note how each "e" has exactly the same incorrect pixels lit.

The only thing I can think of would be to make sure the display is protected from ESD events, and make sure the power supply is stable.

We can get an RMA going for the damaged LCD modules. Please write returns(at)crystalfontz(dot)com, reference this post and request an RMA.

 

[cosmicvoid]

I wonder if perhaps the connection from the pcb to the glass is corrupted, the zebra strip.

 

[CF Tech]

Ya, I considered that, but that kind of failure usually makes vertical or horizontal stripes that are corrupted, and they tend to be located at a given location. Here, the "e" appears several times in different locations with the same odd corruption.

 

[Neily]

It looks like some how the CGROM has been corrupted--note how each "e" has exactly the same incorrect pixels lit.

That's exactly what I was thinking, corrupted CGROM. In this unit it only seems to be affecting the lower case letters. Its not the zebra strip for sure. The letters always display in the same manner no matter where they are on the display. Notice how there is no corruption on the top line, but if I display a different screen with lower case letters on the top line, you will see the same problem on the top line. We are pretty careful about static discharge. Up in Canada here Jan-Feb is pretty dry (and COLD!) creating more of a static problem. Anyway I'll discuss with my boss about the RMA thing.

Thanks.