Lowband Radio Chassis And Transceiver Board Assembly - Motorola CDM Series Basic Service Manual

Maintenance
5. Torque the six screws to 17 in lbs. (1.9 NM) using the T20 TORX™ driver. Begin with the two
screws located in the middle of the chassis followed by the four outer screws. Since the screws
usually take a set, torque the screws a second time (1.9 NM) in the same order.
6. Refit the top cover over the assembled radio chassis. Press the cover down until it snaps into
place.

2.7.3.1 LowBand Radio Chassis and Transceiver Board Assembly

1. Inspect the transceiver board. If the LDMOS final devices (Q1402 and Q1403) were replaced, see
Section 2.6.3.2 as how to replace the thermal pad if necessary.
Note: Thermal grease used with the chassis eliminator, 8180384J61, must be completely
removed from all devices. DO NOT USE THERMAL GREASE on the radio chassis.
This may cause instability of the transmitter under certain load conditions.
2. Insert the transceiver board at an angle (approximately 30°) into the radio chassis taking care to
slide the antenna connector and accessory connector into their cut-outs in the radio chassis.
3. Lower the transceiver board onto the radio chassis and align the two locating holes in the trans-
ceiver board with the locating pins in the radio chassis.
4. Replace the 20-pin accessory connector. Make sure the connector is fully engaged in its opening
before replacing the die cast cover.
5. Replace the die cast cover over the radio chassis making sure the black carbon on the bottom of
the pressure pad is positioned properly over the switch printed on the transceiver board.
Note: The B02 version of the die cast cover will have locating pins to hold the pressure pad
in place on the die cast cover. This will automatically align the pressure pad on the
switch.
6. Secure the die cast cover to the radio chassis with the nine screws previously removed.
7. Torque the nine screws to 17 in lbs (1.9 NM) using the T20 TORX™ driver. Tighten the die cast
cover screws in the sequence labeled on the top of the cover or as shown in Figure 2-10. Since
the screws take a set it is importance to torque the screws a second time (17 in lbs) in the same
order.
8. Insert the plastic protective cover into the 18-pin connector located at the front of the radio chas-
sis.
9. Refit the top cover over the assembled radio chassis. Press the cover down until it snaps into
place.
10. Replace the Control Head per Section 2.7.4.
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