Two rows of white squares on my LCD 2004

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Two rows of white squares on my LCD 2004

Post by Gort » Wed Jun 19, 2019 12:37 pm

Hello Fellow 'LCD 2004 White Block' Battlers,
This is a problem I've been having with several a 'upgraded' RUMBA and TANGO Arduino PCBs running with Windows 10.
I have scoured the web, and this fine forum as usual, but so far I have drawn a blank.

The problem(s):
I have the LCD 2004 display correctly plugged into the EXP1 and EXP2 connectors, I connect the USB with the PCB jumper in the USB power mode and the display presents the usual characters as expected. At first...

I shut down my PC and, on returning the next day, I'm the proud owner of the 20 white blocks on rows 1 and 3. The LCD display is completely unresponsive to all inputs.

On reinstalling my old RAMPS 1.4 PCB, as a test for the LCD, the display works fine. :roll:

I am aware of the screwed-up EXP1 and EXP2 PCB silkscreen outlines on some PCBs so I have tracked the pins from the display to the PCB to ensure that they are all in the correct orientation. This is born out by the fact that they work at first.
My question is: how can it work one minute and not the next? And why does my old PCB work fine all the time?

I have tried uploading a sketch and the compiling and upload appear to work normally. I have the polite 'Thank You' at the end of the upload but still no characters on the LCD 2004.

Pardon my complete ignorance on this subject but I'm wondering if it is possible to 'de-flash' the USB chip which could affect the operation of the LCD?

My only other conclusion is that I have two dud PCBs in a row. A pretty unlikely answer, but I'm getting desperate for some progress with this problem.
As always, any suggestions gratefully received :)


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Re: Two rows of white squares on my LCD 2004

Post by William » Wed Jun 19, 2019 2:36 pm

Hi, Can you provide a specific picture?
-Keep your mind and try to test it. :)
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Re: Two rows of white squares on my LCD 2004

Post by _kaktus_ » Thu Jun 20, 2019 12:39 pm


I suggest that you thoroughly test all connections from the display module to the controller board.

It is possible that there are no contacts somewhere.

The result on the display you are observing indicates that the display is not properly initiated by the software.

If you only connect the new display to the power supply, it will show the same.
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