NEC NF2300-SR412E User Manual page 125

(4) Set the AL-PA and DE-DIAG ID of the adapter for replacement to be the same as
those of the defected adapter.
Before replacing the adapter, make sure that the AL-PA switch of the
adapter for replacement is set to the same value as that of the defected
adapter, as well as the sound adapter. If the adapter is installed with
different setting of AL-PA switch, a link failure may occur in the worst
case.
(5) Insert the adapter for replacement to the slot with the ejector remaining opened until
the adapter is carried to the end securely.
(6) Insert the adapter as far as it will go, and close the ejector.
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