Sainsmart LCD screen not working (light flicker)
April 07, 2014 01:35PM
Hi everyone,

I just finished building my first Prusa Mendel (i2), using an Arduino Mega with RAMPS. I purchased the electronics from Sainsmart along with an LCD screen, and just finished putting everything together.
The LCD screen started working just fine, but after trying out a couple of motors, and switching it off and back on again, it stopped showing anything and just has a strange sort of dim flicker.
I tried uploading the Arduino code again, and as soon as I plugged in the USB cable, the LCD displayed just fine.

I am thinking that it might have something to do with the power supply, but am not sure. Has anyone encountered this issue, or has any suggestions that might solve this?

thanks a lot in advance.


PS. this is my first post here. I am thinking there are going to be quite a few more to come..

Edited 1 time(s). Last edit at 04/07/2014 02:39PM by Hlias.
Re: Sainsmart LCD screen not working (light flicker)
April 07, 2014 07:04PM

I just kept fiddling with the screen to try to resolve the issue, and discovered that if I had the ramps connected to the power supply + the USB cable connected from my computer to the arduino, then the LCD display worked fine and I could control the motors (although the brightness of the display seemed a bit dim compared to normal operation).

I am supposing that it might be an issue of the power supply, but cannot understand how it can be since no motor is running and the hot end is not connected to justify sufficient power drain from the rest of the circuit.

If anyone can help out it would be much appreciated.

Re: Sainsmart LCD screen not working (light flicker)
April 07, 2014 07:33PM
The display is powered by 5V, which is the same voltage provided by the USB port. The hotend and heatbed run on 12V or 24V. Long story short, check your 5V power supply.....
Re: Sainsmart LCD screen not working (light flicker)
April 08, 2014 01:46PM
Thanks. That is what I checked this morning and found out that my LCD screen was getting only 3V for some reason.
What was troubling me was that initially the LCD was working fine, and only after a few runs did it stop working. I am still not sure why it did that, but anyway.

I have solved the problem by supplying 5V directly from the PSU to the 3 pins that are directly next to the reset button on the RAMPS circuit board (to Vcc and gnd) and now it is working just fine.

Thanks and hope this solves it for anyone having the same problem in the future.

So long and thanks for all the fish!
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