NORTHROP GRUMMAN NAVIGAT X MK 1, Operation, Installation And Service Manual

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056343/C NAVIGAT X MK 1
9-2 Replacing Socketed ICs
Exchanging the flash-memory IC
9.2 Replacing Socketed ICs
While all socketed ICs may be easily exchanged, it will mostly be impos-
sible for field service personnel to trace back malfunction of the system
to the failure of a given IC, such as an UART or PAL.
In case of failure of an RS-422 serial data output, however, the reason is
mostly a defective driver IC. The RS-422 serial data outputs use standard
quadruple RS-422 line drivers (MC3487), available from Sperry Marine
under stock no. 46485.
Note The flash-memory IC is a 32-pin PLCC chip. A suitable extractor tool is
required to remove the IC from its socket.
Verify that a new flash-memory IC, stock no. 26562, containing software
4914-1090-00 with the required revision identifier and release date has
been obtained.
1. At the running system, take notes of the current settings in the Man-
ual Settings, User and Service Setup menus. Check that the settings
have been entered correctly into the setup tables in the appendix of
this manual. If necessary, correct and amend the tables.
2. Power down the system.
Make sure that both the main and backup supplies are switched off
and safeguarded against accidental switching-on.
3. Remove the cover from the compass housing.
4. Remove the currently installed flash-memory chip (IC 34) from its
socket on the master PCB.
5. Insert the new flash-memory IC into the socket.
6. Re-attach the cover to the compass housing.
7. Power up the system.
8. Re-enter all settings in the Manual Settings, User and Service Setup
menus, as noted in the setup tables in the appendix of this manual.