Samsung ML-2510, when you insert a new toner printer sends a pulse on the fuse and it blows, and samsung detects new toner has been installed with starter toner cartridge. And this is the way Samsung tell user must replace toner with new.
– The electrical contacts are not in the cartridge but inside the printer: There is a plastic fuse holder on the cartridge, even the starter cartridge. You just simply pop it into the holder. This will stop the flashing red LED and the system tray will say the cartridge is full.
This way is applied to refill toner cartridge.