Display don't work without connecting USB to laptop

I am using Mega 2560, ramps 1.4, reprap full graphics controller, 12V SMPS for my 3D printer

My display don't turn ON without USB connected to laptop.
With USB connected to my laptop, Voltage in dispay pins (Exp1 GND and VCC) is 4.7 V and without USB connected to laptop Voltage is 0 V. so now what should I do?
How can I connect automatically to Printer using only dispay without using my laptop?

What could be the proble for this?

... it's most likely the +5V for the display are feeded from the USB-port, not from the +5V of the Arduino.

Check the current consumption of the display before connecting to the Ardino or it will eventually draw too much current.

Or you can use another power source over USB -- e.g. a +5V wallplug or a powerbank ...

---

Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

It appears that you have a dead 5V regulator on your Arduino controller.
I have replaced mine several time until I modified and added a higher current regular chip to the Arduino Mega2560 board.

There are many different ideals on replacing this regulator chip.
Here is one such youtube video
[www.youtube.com]

---

Computer Programmer / Electronics Technician

Don't waste your time people...

This user has been posting this same thing for 30 days now and just doesn't want or cant understand the answer.

OK!
But let's give the user the benefit of the doubt.
If he cannot figure it out, he could take a laptop to the nearest electronics school show the video too the students / professor they could help him fix it.
Where there is a will there is a way, and this user seems to have plenty of will. And right now I seem to be in abundance of time.

---

Computer Programmer / Electronics Technician