ATMega328 Erratic behaviour on different building power.

Hi All,

This is my first time using the forum and I'm not sure exactly where I should post this question. I have been using the ATMega328 for a while on various projects for personal and work. I have recently been asked to fix a product currently installed on a few sites. The current solution works for a while and then starts to act strangely and then fails.

The Project

This is a simple project with some buttons, LED beacons and sound effects. For this I used a board I made up a while ago for this as I already supply sound effects box for the same sites. These work perfectly and have done for over a year. I had to add in 4x TIP120 to control the LED beacons (12V).

After adding in the LED control I tested the product both in work and at home. This worked perfectly for over 2 weeks in testing.

I sent the product out earlier this week (to be installed in Sweden) and after 5 mins of working fine it began to display the same behaviour as the original boxes it was to replace. The engineer who made the original boards said they were failing because of something to do with the sites power supply. This is a franchise of sites and the same issue seems to be on every site. It seemed to be running small random sections of code and then resetting itself. I have had all this info second hand as I am in the UK and not on site until next week.

I am more of a software guy than hardware so this one is really confusing me. I know the board and circuit work fine because I have been using them for nearly a year (over 50 installed on sites) with no issue. For the power I am using this power supply Stontronics 3A-181WP-09 18W Plug and Go Multi PSU 9V 2A | Rapid Online the same one I use for all these boards and a 7805 to regulate the voltage to 5V.

Finally my questions......

Does anyone have any experience with a project working fine until it is installed on a site where the power supply is questionable? How much could this affect my project?

I have been racking my brains on this one and have no ideas on what to do to fix the issue????

Thanks in advance for any info, help or ideas anyone might have.

You mentioned the beacons need 12 volts. But, there is no mention of a 12 volt supply or how it is inter-connected. Also, no mention of what the total load is on the 5 volt, 2 amp supply. If you're looking for problems with the customers power, start with your own first. What is the maximum current consumption of your device versus the power supply(s) you provided? If you have any inductive loads, do they have free-wheeling diodes installed?

A schematic or at least a block diagram would be a huge help for those of us trying understand what you've built.