Technical Issues with PIN2DMD on realpin

[kbueno]

Hi,
I have a few PIN2DMD devices with some technical issues that I built using the Nucleo-144 F429ZI and the Nucleo Shield (an excellent project developed by Aetios/Frenchclanclan), but I still haven't been able to figure out the root cause of the problem. Any help would be greatly appreciated.

The devices work normally on virtual pinball machines (VPX), but when connected to real pinball machines, they freeze on the startup screen showing the "PIN2DMD" logo, without displaying any game animations.

 

Here’s what has already been checked/tested:

 

-Power supply (5V) is stable.

-Flat cables and signal connections have been verified and tested on more than one real pinball machine.

-In one case, I replaced the Shield PCB while keeping the same Nucleo F429ZI, and the problem persisted.

-I haven't yet tested with a different Nucleo F429ZI.

-I read on some forums that the issue might be related to the 74LS123N IC – this component is present on my PCBs.

 

I would like to proceed with a process of elimination to diagnose the problem. What would you recommend?

 

My main questions are:

 

-What are the most likely causes for this behavior (working on VPX but freezing on real pinball machines)?

-Besides the 74LS123N, are there any other critical components that could be responsible for this issue?

-Is it likely that the problem lies with the Nucleo F429ZI, even though it works fine with VPX? Or can we rule it out because it works in that environment?

-Could it be related to the input signal from the real pinball machine being misinterpreted by the Shield? (Note: plasma displays work fine)

-Could there be a manufacturing issue with the PCBs (e.g., faulty traces, cold solder joints, component tolerance issues)? 

- Is there any way to find out and what necessary tests could I do by exclusion until I can identify the problem?

 

Any help, experience, or suggestions would be greatly appreciated. I'm trying to better understand this behavior to avoid these issues in future builds.

 

Thanks in advance!