Unfortunately, my extruder 8825 driver ended up fried. I guess this might have damaged the Arduino Mega and RAMPS Board.

I tested the Arduino Mega and I'm pretty sure that it is fried too, so I bought a new one. I thought the MOSFETs on the RAMPS are damaged, so I removed them and tested them. One of them was not working, so I bought a new RAMPS Board too

Now I have a new 8825 driver, a new Arduino Mega and a new RAMPS 1.4 but the LCD still doesn't show anything and it just lights up on power up.


1 Answer 1


So basically you just replaced everything except for the LCD (the LCD testing is described a little further). If the LCD is not working then, this could imply that either your LCD is broken, or one of the new parts is not functioning as expected, or you have not connected things correctly.

Are you sure the firmware flash went okay? You could test the Arduino Mega 2560 by connecting it over USB to e.g. Pronterface, you do not need the LCD for testing the Arduino Mega and the RAMPS.

The LCD could be tested separately by creating a sketch in Arduino IDE and connect the correct pins of the LCD cable to some pins of an Arduino device, e.g. load the the U8Glib example sketch "GraphicsTest" and add the following constructor:

U8GLIB_ST7920_128X64_1X u8g(6, 5, 4);  // SPI Com: SCK = en = 6, MOSI = rw = 5, CS = di = 4

This implies that you need to attach the correct pins on the Arduino (in my case to digital pins 6, 5 and 4 for respectively SCK, MOSI and CS to the respective EXP1 pins 5, 3 and 4):

EXP1 wiring for Arduino Uno

Jumper cable wiring full graphical display for testing purposes

Note that you see 5 pins attached, as the LCD needs to be powered (pin 10 on the EXP1 header) and grounded (pin 9 on the EXP1 header).

RepRapDiscount Full Graphic Smart Controller connected to Arduino Uno clone running U8GLIB "GraphicsTest"

I wired this on an Arduino Uno clone and confirmed that 2 of the spare RepRapDiscount Full Graphic Smart Controller clones showed the test program.

PS, this is a simple wiring of the LCD, it displays the test in fade blue-ish, so not the bright colored white pixels, but that is normal!

  • $\begingroup$ mega 2560 is fine. firmware flash was okay. I can send commands via Pronterface. I've tested the motors and endstops. they're ok. I think I should change the question now! How can I test the LCD??? $\endgroup$
    – 2012User
    Dec 26, 2018 at 19:07
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    $\begingroup$ @2012User Just find out how the pins are wired. I have wired LCD with Arduino Uno's, this should not be too different, just find an appropriate sketch. $\endgroup$
    – 0scar
    Dec 26, 2018 at 23:56
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    $\begingroup$ @2012User I have updated the answer with an LCD test and confirmed that it works to test the display. I've tested 2 LCD's to find out that one of the LCD's had the connector shields upside down, so thank you! ;) $\endgroup$
    – 0scar
    Dec 28, 2018 at 13:34
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    $\begingroup$ @2012User Instead of the Arduino Uno, you can use the Arduino Mega, but it is preferred to use an other device to rule out the microprocessor. Please update the question for more specifics, so the answer can be tailored better. $\endgroup$
    – 0scar
    Dec 29, 2018 at 7:41

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