Acrylic Geeetech I3 pro - Problem with Z Axes

[Pietrogramma]

Hi everybody, from a few days I have a problem with the Z Axes of my Acrylic Geeetech I3 pro .
After that I have regulated the height of the nozzle respect at the bed with a sheet of paper in the four corner, I make start the print but the nozzle is very much higher than the adjustment made before.
I tried to flash the firmway of the board GT2560, but the problem is the same.
Before I always used the printer without any problem, the print was perfect but at the suddenly it began to make these problems.
I tried to print using the SD card, thinking it was a problem of the PC, but the same thing happens
You can help me to solve the problem?
I forgot to mention that, as If I remeber correctly, it all happened after a blackout of a few seconds that stopped a printing

[Mark]

is the distance between the nozzle and bed proper after you homing the printer? how's the endstop wiring, does it have a bad contact or something?

[Pietrogramma]

Hi Mark, thanks for your reply.... today I disassembled the board GT2560 of the my Iprusa and when I reassembled the board the printer work fine.
I don't know wich was the problem, I know only that now I print many objects without any problem.
I hope the problem will be solved, even if I do not understand what may have been the reason for the failure .
I will never know if there will be other problems .
Hello

[Mark]

[Pietrogramma]

All this is really unusual.
In your opinion could be a power problem?
often I hear that the cooling fan has voltage dips.
These days I will try to use a power supply of the xbox360.
Thanks and bye bye