Samsung ML 2550 - Manual (Page 207)

P ROGRAMME I NSTALLING P RINTER O PTIONS F.2
Precautions When Installing Printer
Options
DISCONNECT THE POWER CORD:
Never remove the printer control board while the printer is
plugged in.
To avoid the possibility of an electrical shock, always disconnect
the power cord when installing or removing ANY internal or
external printer option.
DISCHARGE STATIC ELECTRICITY:
The control board and internal printer options (Memory DIMM,
Network and Serial interface cards) are sensitive to static
electricity. Before installing or removing an internal option,
discharge static electricity from your body by touching
something metal, such as the metal back plate on any device
plugged into a grounded power source. If you walk round before
finishing installation, discharge any static electricity once again.