Brother HL-7050N - Manual (Page 141)

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HL7050_US_UG_FM5.5
Installing extra DIMM memory
When you install extra memory, follow these steps:
1 Turn off the printer power switch, and then unplug the printer.
Disconnect the interface cable from the printer.
2 Remove the side cover.
Figure 4-10
Make sure you turn the power to the printer OFF before you
install or remove the DIMM.