Motorola Pr400 Basic 6881096c24 A Manual

							Chapter 6 Full Keypad Model Disassembly and
Re-assembly
6.1 Introduction
This section provides details about the following:
• Preventive maintenance (inspection and cleaning)
 Safe handling of CMOS and LDMOS devices
 Disassembly and re-assembly of the radio
 Repair procedures and techniques
6.2 Preventive Maintenance
The radios do not require a scheduled preventive maintenance program; however, periodic visual 
inspection and cleaning is recommended.
6.2.1 Inspection
Check that the external surfaces of the radio are clean, and that all external controls and switches are 
functional. It is not recommended to inspect the interior electronic circuitry.
6.2.2 Cleaning Procedures
The following procedures describe the recommended cleaning agents and the methods to be used 
when cleaning the external and internal surfaces of the radio. External surfaces include the front 
cover, housing assembly and battery case. These surfaces should be cleaned whenever a periodic 
visual inspection reveals the presence of smudges, grease, and/or grime. 
The only recommended agent for cleaning the external radio surfaces is a 0.5% solution of a mild 
dishwashing detergent in water. The only factory recommended liquid for cleaning the printed circuit 
boards and their components is isopropyl alcohol (70% by volume).
Cleaning External Plastic Surfaces
Apply the 0.5% detergent-water solution sparingly with a stiff, non-metallic, short-bristled brush to 
work all loose dirt away from the radio. Use a soft, absorbent, lintless cloth or tissue to remove the 
solution and dry the radio. Make sure that no water remains entrapped near the connectors, cracks, or 
crevices.Note:
Internal surfaces should be cleaned only when the radio is disassembled for service 
or repair.
CAUTION: The effects of certain chemicals and their vapors can have harmful results on certain plas-
tics. Avoid using aerosol sprays, tuner cleaners, and other chemicals.
! 
						

							July, 20046881096C24-A
6-2Full Keypad Model Disassembly and Re-assembly: Safe Handling of CMOS and LDMOS Devices
Cleaning Internal Circuit Boards and Components
Isopropyl alcohol (70%) may be applied with a stiff, non-metallic, short-bristled brush to dislodge 
embedded or caked materials located in hard-to-reach areas. The brush stroke should direct the 
dislodged material out and away from the inside of the radio. Make sure that controls or tunable 
components are not soaked with alcohol. Do not use high-pressure air to hasten the drying process 
since this could cause the liquid to collect in unwanted places. After completing the cleaning process, 
use a soft, absorbent, lintless cloth to dry the area. Do not brush or apply any isopropyl alcohol to the 
frame, front cover, or back cover.
6.3 Safe Handling of CMOS and LDMOS Devices
Complementary metal-oxide semiconductor (CMOS) devices are used in this family of radios, and are 
susceptible to damage by electrostatic or high voltage charges. Damage can be latent, resulting in 
failures occurring weeks or months later. Therefore, special precautions must be taken to prevent 
device damage during disassembly, troubleshooting, and repair. 
Handling precautions are mandatory for CMOS circuits and are especially important in low humidity 
conditions. DO NOT attempt to disassemble the radio without first referring to the following CAUTION 
statement.  Note:
Always use a fresh supply of alcohol and a clean container to prevent contamination by 
dissolved material (from previous usage).
CAUTION: This radio contains static-sensitive devices. Do not open the radio unless you are properly 
grounded. Take the following precautions when working on this unit:
 Store and transport all CMOS devices in conductive material so that all exposed 
leads are shorted together. Do not insert CMOS devices into conventional plastic 
“snow” trays used for storage and transportation of other semiconductor devices.
 Ground the working surface of the service bench to protect the CMOS device. We 
recommend using the Motorola Static Protection Assembly (part number 
0180386A82), which includes a wrist strap, two ground cords, a table mat, and a 
floor mat.
 Wear a conductive wrist strap in series with a 100k resistor to ground. (Replacement 
wrist straps that connect to the bench top covering are Motorola part number RSX-
4015.)
 Do not wear nylon clothing while handling CMOS devices.
 Do not insert or remove CMOS devices with power applied. Check all power 
supplies used for testing CMOS devices to be certain that there are no voltage 
transients present.
 When straightening CMOS pins, provide ground straps for the apparatus used.
 When soldering, use a grounded soldering iron.
 If at all possible, handle CMOS devices by the package and not by the leads. Prior 
to touching the unit, touch an electrical ground to remove any static charge that you 
may have accumulated. The package and substrate may be electrically common. If 
so, the reaction of a discharge to the case would cause the same damage as 
touching the leads.! 
						

							6881096C24-A     July, 2004
Full Keypad Model Disassembly and Re-assembly: Disassembling and Re-assembling the Radio — General 6-3
6.4 Disassembling and Re-assembling the Radio — General
Since these radios may be disassembled and re-assembled with the use of only four (board to casting) 
screws, it is important to pay particular attention to the snaps and tabs, and how parts align with each other.
The following tools are required for disassembling the radio (see Chapter 4 for a list of service aids):
 Knob remover/chassis opener
 Penknife-size screwdriver
 TORX™ T6 screwdriver
 Scribe
If a unit requires more complete testing or service than is customarily performed at the basic level, 
send this unit to a Motorola Authorized Service Center. See Appendix B for a list of authorized service 
centers.
The following disassembly procedures should be performed only if necessary:  Chassis Disassembly
 Speaker Disassembly
 PTT Disassembly
6.4.1 Radio Disassembly — Detailed
6.4.1.1  Front Cover Fr om Chassis Disassembly
1.Turn off the radio.
2. Remove the battery ( Figure 6-1):
a. Slide the battery latch into the unlock position. Disengage by pushing downward and  holding the latch towards the front of the radio.
b. With the battery latch disengaged, slide the battery down from the top of the radio about  1/2 in. Once the battery is free from the battery rails, lift it directly away from the radio.
c. Remove the battery from the radio.
Figure 6-1.  Battery Removal
Battery Latch
LockUnlock 
						

							July, 20046881096C24-A
6-4Full Keypad Model Disassembly and Re-assembly: Disassembling and Re-assembling the Radio — General
3.Remove the antenna.
4.Pry off the volume and channel selector knobs from their shafts using the knob removal/chassis 
opener tool (Motorola part # 6686533Z01). (Figure 6-2).
5.Separate the chassis from the front housing assembly by using the knob remover/chassis opener 
too. Place the broad side of the opener into the slots located at the base of the radio (Figure 6-3). 
Press the handle on the opener downwards. This pressing action forces the thin inner plastic wall 
toward the base of the radio, releasing the two chassis base tabs.  
6.Pull the chassis assembly out of the front cover only until the volume and channel selectors shaft 
just clear the top of the case. (Figure 6-4). Figure 6-2.  Antenna and Knob Removal
Note:
Both knobs slide on and off. However the knobs are designed to fit very tightly on the shaft.
Figure 6-3.  Chassis Removal
CAUTION: Marring the front cover O-ring sealing area will prevent the radio from sealing properly. If the 
O-ring is damaged, replace it with a new one.
 
Radio Chassis
Knob Remover/
Chassis Opener
! 
						

							6881096C24-A     July, 2004
Full Keypad Model Disassembly and Re-assembly: Disassembling and Re-assembling the Radio — General 6-5
7.Rotate the bottom of the chassis up about 20 ° to disconnect the keyboard flex cable connector. 
Push down 2 end tabs to release flex connector at the bottom of the chassis.
8. Rotate the chassis counterclockwise out of the housing and position next to the housing. Take 
care not to damage the speaker  and microphone wires that are still connected to the chassis 
( Figure 6-5 ).
9. Unplug the speaker wire assembly from the 2-pin connector on the chassis.
10. Unplug the microphone wire assembly from the socket on the chassis.
11. Move the chassis away from the housing and place on a clean work surface.
Note:
The speaker wire assembly microphone wire as
sembly and keypad flex cable connector
connecting the front housing assembly and t he chassis prevent the two units from being
completely separated  
Figure 6-4.  Keyboard Flex Connection
Figure 6-5.  Microphone and Speaker Connections
Radio Chassis Flex Connector
Speaker Connector
Microphone
Connector 
						

							July, 20046881096C24-A
6-6Full Keypad Model Disassembly and Re-assembly: Disassembling and Re-assembling the Radio — General
6.4.1.2  Dust Cover Disassembly
1.Gently pry the top of the dust cover away from the body of the radio. (See Figure 6-6).
2.Rotate the dust cover 90° in a counterclockwise direction to allow the key to be removed.
3.Separate the dust cover away from the body of the radio. The dust cover key is fragile; apply only 
light pressure to the key while removing the dust cover.
Figure 6-6.  Dust Cover Disassembly
6.4.1.3  Speaker and Microphone Disassembly 
1.Remove the screw from the speaker retainer using a T6 Torx screwdriver (Figure 6-7).
2.Lift the retainer off the speaker, sliding end of retainer out of corner slot on the housing.
3.Lift the speaker out from the front housing.
4.Carefully lift microphone assembly out of housing. Note:
The speaker is held in place with a retainer bracket. Be careful not to damage the speaker
when removing the retainer bracket.
Figure 6-7.  Removal Speaker-Microphone Assembly
c. Separate dust b. Rotate dust cover 90° to
a. Pry dust cover from body.
key
allow key to be removed.cover from body.
Retainer Bracket
Radio Housing
Speaker
Speaker Connector
Microphone Connector
Microphone 
						

							6881096C24-A     July, 2004
Full Keypad Model Disassembly and Re-assembly: Disassembling and Re-assembling the Radio — General 6-7
6.4.1.4  Keyboard Removal
1.Carefully pry the four keypad retainer locking tabs free from the housing using a scribe.
2. Lift the keypad retainer up from the bottom and slide the top tabs out.
3. Slide keypad retainer out of housing carefully to prevent damage to flex cable.
4. Lift LCD keypad board out of housing ( Figure 6-8).
5. Lift keypad out of housing.
6.4.1.5  PTT Disassembly
1.If required, the PTT ( Figure 6-9 can be disassembly using a small screwdriver, as follows:
a. Insert the tip of a small screwdriver underneath the PTT and unsnap the top tab.
b. Pry the PTT away from the radio housing.
c. Inspect the two hooks. If bent or broken, the PTT must be replaced.
d. Remove the PTT seal.
Note:
Use care when removing the keypad retainer to prevent damage to the keyboard flex
cable.
CAUTION: 
 Refer to the CMOS CAUTION paragraph (6.3) befo re removing the main board. Be sure to 
use Electrostatic Discharge protectio n when handling circuit boards.
Figure 6-8.  Keypad Removal
!
Keypad
Keypad Retainer
Flex Cable
Keypad Board 
						

							July, 20046881096C24-A
6-8Full Keypad Model Disassembly and Re-assembly: Disassembling and Re-assembling the Radio — General
6.4.1.6  Chassis Disassembly
1.Remove the O-ring.
2.Use a Torx™ screwdriver with a T6 bit to remove the four screws (Figure 6-10) holding the main 
board to the chassis.
.
3.The audio jack shroud can be removed from the main board.Figure 6-9.  PTT Removal
CAUTION:  Refer to the CMOS CAUTION paragraph (see 3.3) before removing the main board. Be sure 
to use Electrostatic Discharge protection when handling circuit boards.
Figure 6-10.  Removal of Main Board from Chassis
Flat BladeScrewdriver
PTT Seal
Ta b
Ta b
Hooks
!
Main Board
Radio Chassis
Audio Jack Shroud
O-Ring 
						

							6881096C24-A     July, 2004
Full Keypad Model Disassembly and Re-assembly: Disassembling and Re-assembling the Radio — General 6-9
4.Lift the main board from the chassis ( Figure 6-10).
5. Remove the battery contact seal.
6.4.2 Radio Re-assembly - Detailed
6.4.2.1  Dust Cover Re-assembly
1.Insert the tail of the dust cap into the bottom hole of the audio jacks housing opening
(Figure 6-11 ).
2. Press the dust cap until the  tail is fully into the hole.
3. Twist the dust cap counter-clockwise until the cap is seated properly onto the recess.
4. Press the cap again to ensure it fully covers the opening for the audio jack.
.
6.4.2.2  Microphone and S peaker Re-assembly
1.Check that the mic and speaker felts are in position and not damaged. If damaged replace felts.
2. Insert the microphone sub-assembly into the microphone boot.
3. 3. Insert the Boot and microphone sub-assembly into the microphone recess in the housing and 
route wires as shown in  Figure 6-12.
Note:
Make sure the dust cap is placed between the keypad retainer mounting post and the side
wall of the radio.
Figure 6-11.  Dust Cap Re-assembly
12 34 
						

							July, 20046881096C24-A
6-10Full Keypad Model Disassembly and Re-assembly: Disassembling and Re-assembling the Radio — General
4.Locate the speaker tab and align it with the tab opening in the front housing (Figure 6-13).
5.Insert the speaker tab into the speaker recess in the housing. Ensure the speaker is seated flush 
in the housing.
6.Insert one end of the speaker retainer into the slot in the front housing (See Figure 6-13).
 
7.Install the retainer screw using a T6 Torx screwdriver. Torque to 2.3 - 2.5 lb/in.Figure 6-12.  Microphone Re-assembly
Note:
Make sure the speaker and microphone wires are routed tightly between the speaker bas-
ket and the housing post.
Figure 6-13.  Speaker Re-assembly
Note:
When fastening the speaker retainer screw, make sure the wires are out of the way to pre-
vent pinching by the retainer.
Microphone
Boot
Microphone Recess
Microphone Position
Speaker Retainer
Speaker
Front Housing Slot
Ta b  O p e n i n g
Speaker Tab