Appendix B: Ms2721A Case Replacement Instructions (Kit # Nd64730) - Anritsu Spectrum Master MS2721A Maintenance Manual

15. Appendix B: MS2721A Case Replacement Instructions (Kit # ND64730)

This procedure is used with Kit # ND64730 to convert the early MS2721A aluminum case to the current plastic case.
Note that if any part of the aluminum case needs to be replaced, the entire case must be replaced using this kit. For more
information, refer to Anritsu Service Note MS2721A-4, or contact your nearest Anritsu Service Center.
1. Place unit face down on an ESD safe protective platform with test port facing away from you. Remove battery
door and battery pack. Remove four case screws found at each corner.
2. Carefully begin to lift bottom case off. Only lift the right side just high enough to view cables that attach both
halves of the case together. Observe location and routing of all cables (very important) as you will need to re-
place them in the identical locations when reinstalling them into the new poly case.
3. Carefully disconnect the black coax cable from the main PCB assembly connection marked EXT REF.
4. Carefully disconnect the black coax cable from the main PCB connection marked J3007.
5. Carefully disconnect the cable that comes from J9007 of the Spectrum Analyzer module from the connector
marked 100M SPA on the main PCB assembly.
6. Carefully disconnect the cable that comes from J3008 of the Spectrum Analyzer module from the connector
marked 37.8M IN on the main PCB assembly.
7. Carefully disconnect the ribbon cable that connects the Spectrum Analyzer module to the main PCB assembly
at connector J3000.
8. Separate the two halves and set the bottom half aside for now.
9. Unplug the Fan, Battery and Encoder Knob cable harnesses from the Mother Board.
10. Remove eight perimeter screws plus one screw next to the encoder knob.
11. Carefully lift the Mother Board straight up off the keypad connection header then back and all the way out and
set aside for now. Remove the encoder PCB and harness assembly by removing the encoder knob and nut on
the front side.
12. Reassemble encoder knob, encoder PCB and harness assembly into new Poly case in reverse order. Remove the
tape holding the LCD protective cover onto the new poly case. Leave the LCD protective cover where it is and
clean it from any dust and smudge marks in preparation for assembly. For cleaning, use either Reztore ESD
surface + mat cleaner or pure Isopropyl Alcohol with a lint free cloth.
13. Install the Mother Board in the reverse order into the poly case as previously removed from the aluminum case.
Observe alignment of keypad connection header. As a help to alignment, observe correct alignment of encoder
knob screw hole with the female threads on the inside top case.
14. Plug in the Fan, Battery and Encoder Knob harnesses into the Mother Board. Temporarily install the battery
pack and power on the unit and observe weather or not the Anritsu logo appears on the screen. This will verify
that the keypad connection header was properly fitted. After verification, turn unit off and remove the battery
pack.
15. Using the new screws supplied, install the eight perimeter screws plus one screw next to the encoder knob. This
completes the top half, set aside for now.
16. Remove five perimeter screws (one screw should be missing from the bottom right side) from bottom case
Spectrum Analyzer Module. Remove the Spectrum Analyzer Module from the aluminum case.
17. Remove four nuts from the test port adapter to the panel. Remove three screws attaching the panel to the Spec-
trum Analyzer Module. The panel can now be pulled straight out and off. Remove the two BNC cables from
the panel.
18. In reverse order attach the two BNC cables to the new panel. Slide the panel onto the test port adapter and then
use the three screws to reattach the panel to the Spectrum Analyzer Module, do not tighten the 3rd (short) screw
all the way to the right yet. This screw will be tightened when the panel is first correctly aligned into the new
poly case grooves. Install the four nuts onto the test port adapter to panel and tighten all the way.
Spectrum Master MM 43