RR Discount Full Graphic Smart Controller (LCD 12864) issue - clicking while turning

Hi,

I've bought a chineese LCD controller board for Arduino Mega 2560/RAMPS, the one with SD slot, encoder, buzzer & reset button.

It seems to connect to Merlin software and displays all the information however when i turn the knob, it often randomly behaves as if it was pressed (clicked).
It buzzes and enters options under the highligted line...

I thought that it is bad encoder so I changed it but the behavior persists.
Could anyone suggest what else this issue may be related to, how to find the root case and fix it?
(I don't want to change it cause it takes weeks for those packages to come from China and that's why I'd like to try fixing it).
The controller board seems pretty simple, but I'm very new to electronics, so I need some of your help...

Thanks,
alwi

Edited 1 time(s). Last edit at 10/15/2015 06:20AM by alwi.

Looks like the issue is not in the controller.
I've bought another set of arduino mega & ramps and after quick check by uploading Marlin & connecting the controller, it seems to actually be working fine.

Now I need to figure out which one of them: arduino or ramps is bad and why...

Edited 1 time(s). Last edit at 10/16/2015 03:07AM by alwi.