Assembly Removal and Replacement, MS203xC 7-20 Replacing Rotary Encoder – 3-410-101
MS20xxC MM PN: 10580-00307 Rev. D 7-49
7-20 Replacing Rotary Encoder – 3-410-101
Replacing the Rotary Encoder involves removing the Rotary Knob, and then opening the case and partially
removing the VNA PCB Assembly. If the GPS Receiver Module (Option 31) is installed, then the GPS Antenna
must be disconnected. After the VNA PCB Assembly is “folded” out of the way, the Rotary Encoder mounting
hardware can be loosened from the Front Panel, and its cable detached from the Main PCB Assembly. The
Main PCB Assembly and Keypad Bezel need not be removed to replace the Rotary Encoder.
Part Numbers
• 3-410-101 – Rotary Encoder
• For MS2036C, MS2037C and MS2038C instruments
• Includes the connection cable to the Main PCB Assembly, for connector J5010
• Does not include the Rotary Knob – 3-61360-2
Procedure
Removing the Rotary Knob:
1. Use a flat-blade screwdriver and piece of rubber (as a fulcrum) to remove the Rotary Knob.
2. Use a 7/16 inch (≅ 12 mm) nut driver to remove the nut, lock washer, and flat washer that hold the
Encoder in place. Save the nut, star washer, and flat washer for use on the replacement Rotary Encoder.
Opening the Case:
3. Open the case as described in Section 7-16 “Opening the Instrument Case” on page 7-26
Disconnecting GPS Antenna Cable (if Option 31 is Installed):
4. If Option 31 is not installed, then skip to Step 5. If Option 31 is installed, then disconnect the GPS
Antenna SMA connector from the top connector panel by performing the following sub steps:
a. Use two 5/16 inch (≅ 8 mm) end wrenches to disconnect the GPS Antenna SMA connector (item 11
in Figure 7-18 on page 7-38) from the top connector panel.
b. Pull off the nut and lock washer and remove the SMA connector from the top connector panel.
c. Replace the lock washer and nut onto the SMA connector for safe keeping.
d. Route the cable to the right side, clearing its notch and the top connector panel, so it is clear of the
VNA PCB Assembly and the Case Front Assembly.
Removing Cables:
5. Cut the cable tie (if used) that holds the Ext Trig Input (item 1 in Figure 7-18) and Ext Ref Input (item 2
in Figure 7-18) coaxial cables to the RF Out semi-rigid coaxial cable.
Identifying VNA PCB Assembly Mounting Screws:
6. Using Figure 7-23, identify the locations of the eight (8) Phillips-head mounting screws that hold the
VNA Assembly PCB in place. Figure 7-20 on page 7-40 shows the 8 hexagonal standoffs on the Mother
Board. The 8 VNA Assembly PCB screws attach to the 8 hexagonal standoffs in the Main PCB (Mother
Board). The general locations of the 8 hexagonal standoffs are also visible in Figure 7-4 on page 7-6 and
Figure 7-6 on page 7-8.
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