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Smart controller screen unreadable, Marlin setting or bad screen?

Posted by HugoW 
Smart controller screen unreadable, Marlin setting or bad screen?
November 18, 2018 07:34AM
Hi,

my new screen, the famous RepRapDiscount Full Graphics Controller, is unreadable unless you check at very specific anlges:

[www.youtube.com]

Is it a setting on Marlin I can change to fix this? The potmeter on the bottom of the board doesn't seem to do anything. Please advise.

Cheers,

Hugo
Re: Smart controller screen unreadable, Marlin setting or bad screen?
November 18, 2018 07:53AM
On the Front of LCD there is a Contrast control potentiometer you can see it is blue and white.
Adjust for the best LCD display.


Electronics Technician / Computer Programmer
Re: Smart controller screen unreadable, Marlin setting or bad screen?
November 18, 2018 08:00AM
That's what I feared, that potentiometer does next to nothing. The video shows it in it's most optimum setting, in only gets worse if I turn it the other way.

Hugo
Re: Smart controller screen unreadable, Marlin setting or bad screen?
November 18, 2018 08:08AM
That issue is well known,,,

this issue is that they have a contrast on the lcd module (where you cant get to it) and on the main board... they should have removed the one on the lcd...

I know of two fixes for this

1) solder a resistor between pins 2 and 3 on the display (the value depends on where they left the pot you cant change) see [reprap.org]
I have personally had to do this to a few boards and know it works well

2) some have removed the blue and white variable resistor. I have not personally tried this one, It leaves you with no way to adjust the contrast, but seem to work, according to this youtube [youtu.be]
Re: Smart controller screen unreadable, Marlin setting or bad screen?
November 18, 2018 09:00AM
Well, I just tried all solutions in de linked topic, to no avail. I also measured all voltages everywhere I could, they are all OK. I think I have a faulty LCD... Bummer...

Hugo
Re: Smart controller screen unreadable, Marlin setting or bad screen?
November 18, 2018 10:20AM
This is entirely possible, though I believe Dust is correct and it is just a back-light problem.

More information here
[reprap.org]


Electronics Technician / Computer Programmer
Re: Smart controller screen unreadable, Marlin setting or bad screen?
November 18, 2018 11:04AM
The other common reason for poor contrast on Arduino Mega/RAMPS setups is that the 5V regulator on the Arduino is not capable of powering the Arduino + 12864 display without overheating. As a result the voltage on the 5V rail sags to significantly less than 5V. This causes a few issues, including messing up the contrast setting on the LCD and overheating of the bed mosfet on the RAMPS. If this is the cause, then providing 5V power via the USB connector is one of several workarounds.

Edited 1 time(s). Last edit at 11/18/2018 11:05AM by dc42.



Large delta printer [miscsolutions.wordpress.com], Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Smart controller screen unreadable, Marlin setting or bad screen?
November 18, 2018 11:08AM
Well, it looks like the backlight is well adjustable, but the graphics just aren't clear...

Hugo
Re: Smart controller screen unreadable, Marlin setting or bad screen?
November 21, 2018 12:24PM
I already replaced my Mega's voltage regulator with an LM7805CV, rated for 1,5A (and it can take 24V). And I have the same result when I power it over USB, with plenty of power over the 5V available. I measure 4,988V on my mulitimeter, I doubt 0,012V makes it go wrong.

I just made this clip but they cannot see it in China so they think I am pulling their leg:

[www.youtube.com]

At 1:17 you can see there is something going on on the screen and the knob is functional. It's difficult to film and poperly zoom.

Hugo

Edited 2 time(s). Last edit at 11/21/2018 12:28PM by HugoW.
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