I was siting in the shop today with a samsung scx 4725fn. It just kept on rebooting.
I changed the toner, bad toner will cartridge will cause this issue.
I changed the fuser. The fuser doesn’t warm up to a certain temperature within a certain period of time. Try replacing the thermistor.
My next two options are either a bad main board or a bad power supply.
I changed all the electrolytic caps on the power supply that fixed the issue.
If that did not work then it would be time to reheat each board with a hair drier. This would take care of any solder problem.
If that did not fix it. The next step would be the main board. why… well a bad power supply can shunt too much current to the main board. This can result in chip failure.
Another possibility is laser failure. This also causes samsung scx 4725 reboot error.
Keep in mind, I had nothing else doing all day… With the price of these machines being very low, it would have been simpler to junk the machine but I made it a learning project since we had parts laying all over the place for this machine.