Epson AcuLaser C1900 Reference Manual page 182

Note:
If you used the Hard Disk Drive in other EPSON's printer before, such
as the AcuLaser-C8600 or the AcuLaser-C4000, you have to format the
Hard Disk Drive. See "Formatting the Hard Disk Drive" on page 186
for details.
1. Turn the printer off and unplug the power cord.
2. Remove all interface cables from the interface connectors.
3. Loosen the five screws on the back of the printer, and remove
the shield.
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Installing Options