Motorola Cp185 Basic 68007024004 Manual

							Chapter 6  Maintenance – CP185
6.1 Introduction
This section provides details about the following:
• Preventive maintenance (inspection and cleaning)
• Safe handling of CMOS and LDMOS devices
• Disassembly and reassembly of the radio
• Repair procedures and techniques
• Mechanical View and Parts List
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 (100% by volume).Note:
Internal surfaces should be cleaned only when the radio is disassembled for service 
or repair.
The effects of certain chemicals and their vapors can have harmful results on certain plastics. 
Avoid using aerosol sprays, tuner cleaners, and other chemicals. 
						

							6-2Maintenance – CP185: Safe Handling of CMOS and LDMOS Devices
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.
Cleaning Internal Circuit Boards and Components
Isopropyl alcohol (100%) 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).
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 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 
4280385A59.)
• 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. 
						

							Maintenance – CP185: Disassembling and Reassembling the Radio – General 6-3
6.4 Disassembling and Reassembling the Radio – General
When disassembling and reassembling the radio, 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 and reassembling the radio (see Chapter 3 for a list 
of service aids):
• Phillips Screwdriver
• Flat Head Screwdriver
• Torque Driver
• Crab Eye Nut Opener (PMDN4039_R)
• Chassis and Knob Opener (PMDN4038_R)
•Tweezers
If a unit requires further testing or service than is customarily performed at the basic level, please 
send the unit to a Motorola Authorized Service Center listed in Appendix B.
Note:
Numbers in parentheses ( ) refer to item numbers in Figure 6-19, on page 6-15.
Figure 6-1.  Limited Keypad With Channel Knob Model 
						

							6-4Maintenance – CP185: Disassembling and Reassembling the Radio – General
6.4.1 Radio Disassembly – Detailed
6.4.1.1  Front Housing From Chassis Disassembly
1.Turn off the radio.
2.Remove the Battery (31):
a. Release the battery latch by moving it into the unlock position.
b. Slide the Battery downwards.
c. Remove the Battery from the radio.
3.Remove the Antenna (22) by turning it counterclockwise.Figure 6-2.  Battery and Antenna Removal
AntennaBelt Clip
BatteryBattery Latch 
						

							Maintenance – CP185: Disassembling and Reassembling the Radio – General 6-5
4.Remove the Volume Knob (7) and Channel Knob (8) from their shafts using the Chassis and 
Knob Opener. (Refer Figure 6-3).
5.Separate the Chassis (27) from the Front Housing Assembly (1):
a. Insert the Chassis and Knob Opener in between the thin retaining wall and the chassis 
at the bottom of the radio. Do not mar the O-ring sealing area on the housing.
b. Slowly pry the bottom of the chassis from the housing by pushing the Chassis and Knob 
Opener downwards, and prying the handle of the tool over and behind the base of the 
radio. This forces the thin inner plastic wall toward the base of the radio thus releasing 
the two chassis base tabs. (Refer Figure 6-4).
Figure 6-4.  Chassis RemovalFigure 6-3.  Knobs Removal
Note:
Both knobs can be turned clockwise and counterclockwise. However, they are designed to
fit very tightly on their shafts.
Marring the front cover O-ring sealing area will prevent the radio from sealing properly. If the 
O-ring (24) is damaged, replace it with a new one.
Volume Knob
Channel Knob
Chassis and Knob Opener 
						

							6-6Maintenance – CP185: Disassembling and Reassembling the Radio – General
c. Slide the rear chassis downwards, and away from the front housing. Be careful not to 
damage the Flexible Cable (39) and speaker wire underneath. (Refer Figure 6-5). 
d. Remove the speaker wire connector connecting the main circuit board and the internal 
speaker on the front housing with the tweezers. (Refer Figure 6-6).
e. Lay the front housing down. Rotate the chassis sideways from the Front Housing 
Assembly (1) and lay it down.Figure 6-5.  Speaker Wire and Flexible Cable Connection
Note:
The speaker wire and flexible cable connector connecting the Front Housing Assembly (1)
and the Chassis (27) prevent the two units from being completely separated 
Figure 6-6.  Speaker Wire Removal
Speaker Wire
Flexible Cable
Speaker Connector 
						

							Maintenance – CP185: Disassembling and Reassembling the Radio – General 6-7
f. Push the latches on the Front Circuit Board (41) sideways to the right to release the 
flexible cable from the connector. (Refer Figure 6-7).
6.4.1.2  Chassis Assembly Disassembly
1.Remove the Accessory Bracket (35).
2.Remove the nut (17) on the On/Off Volume Knob Shaft and Channel Knob Shaft with the Crab 
Eye Nut Opener.
3.Remove the screw holding the Sub Circuit Board (16) to the Chassis (27) with a Phillips 
screwdriver. 
4.Push the latches on the Main Circuit Board (19) to release the Flexible Cable (39) from the 
connector.
5.Remove the Sub Circuit Board from the Chassis. (Refer Figure 6-8).
6.Remove the six screws (37) holding the Main Circuit Board to the Chassis with a Phillips 
screwdriver. Remove the RF Support Screw (20) with a flat head screwdriver.Figure 6-7.  Unlatch the Flexible Cable
Figure 6-8.  Sub-Circuit Board and Accessory Bracket Removal
Latches
Nuts
Accessory Bracket
Sub Circuit Board
Accessory Bracket
Latch 
						

							6-8Maintenance – CP185: Disassembling and Reassembling the Radio – General
7.Remove the Main Circuit Board from the Chassis.
8.Remove the seven small O-ring retainers from their slots in the Chassis. Note the alignment of 
the retainers for reassembly.
9.Remove O-ring (24) and the Battery Contact Seal (28). (Refer Figure 6-9).
6.4.1.3  Front Circuit Board, Display Module and Keypad Disassembly
1.Push the latches on the Front Circuit Board (41) to release the Liquid Crystal Display (LCD) 
flexible cable from the connector.
2.Remove the five screws holding the Front Circuit Board to the Front Housing with a Phillips 
screwdriver. 
3.Remove the Front Circuit Board from the Front Housing. (Refer Figure 6-10).
Refer to the CMOS CAUTION paragraph under Section 6.3 before removing the main board. Be 
sure to use ESD protection when handling the circuit boards.
Figure 6-9.  Main Circuit Board, O-ring and Battery Contact Seal Removal
Figure 6-10.  Front Circuit Board Removal
O-Ring
Battery Contact Seal
Circuit Board 
						

							Maintenance – CP185: Disassembling and Reassembling the Radio – General 6-9
4.Remove the LCD (38), Poron Pad (44) and Keypad (43) from the Front Housing. 
(Refer Figure 6-11).
6.4.1.4  Speaker Disassembly
1.Remove the screw holding the Speaker Retainer (11) to the Front Housing with a Phillips 
screwdriver.
2.Remove the Speaker Retainer from the Housing.
3.Remove the Speaker from the Housing with a flat head screwdriver.
4.Remove the Speaker Insulator (12) from the speaker.Figure 6-11.  LCD and Keypad Removal
Note:
The poron pad will be damaged during disassembly. A new poron pad is needed for
reassembly.
Note:
Be careful not to damage the Speaker Wire when removing the Retainer Bracket.
Poron Pad
LCD
Keypad 
						

							6-10Maintenance – CP185: Disassembling and Reassembling the Radio – General
5.Remove the Speaker Felt (9) from the grille area. (Refer Figure 6-12).
Figure 6-12.  Speaker Removal
Speaker Retainer
Speaker 
Speaker Felt
Speaker Insulator