Correct, Paul. That's exactly what you said about the components used in the Matrix.
I put the Matrix, along with the RTC, inside a box and soldered several wires, making it impossible to disassemble it. I also tested it with a 5V 4A Wall Power Supply, but it was the same. Thank you very much for your help.
No, actually I haven't understood the circuit. I can't understand why there are only 4x APM4953 when there are 4x 74HC138. There should be 4x APM4953 for each 74HC138.
It would make sense to me if there were 2x 74HC138 and 8x APM4953 for the whole display, or 2x 74HC138 and 8x APM4953 for each half of the display.
So what you are saying is that you have given up hope of fixing any hardware problem causing the ghosting and you are hoping it is a software problem. Unfortunately I could not see any problem in the software, so I think the ghosting can't be fixed.
But, given that the Matrix already has all the electronics soldered in and, as you said, "it looks like a cheap project", do you think there would be a way to fix the hardware? Yes, I'm being honest with my question.
No, it is a generic 5V 4A (Wall) power supply.
PS.: And I read somewhere (assembly manual?), that this Matrix requires 5V 2A.
Power Requirements
There's a lot of LEDs! You may need up to 4A per panel. We suggest our 4A regulated 5V adapter and then connecting a 2.1mm jack. Please check out our tutorials for more details
I can't think of one.
That panel is a 1:8 multiplexed panel, so it will use about 2x the current of @Dancopy 's 1:16 multiplexed panel.