Motorola Cdm And Pro Series Detailed 68p81091c63 O Manual

Theory of Operation2-37
2.11 Control Head (PRO5100, PRO7100, CDM1250, CDM1550)
The control head contains the internal speaker, the on/off/volume knob, the microphone connector, 
several buttons to operate the radio, several indicator light emitting diodes (LEDs) to inform the user 
about the radio status, and a 14 character liquid crystal display (LCD) for alpha - numerical 
information, e.g. channel number or call address name. To control the LED’s and the LCD, and to 
communicate with the host radio...

2-38Theory of Operation
The µP determines the used keypad type and the control head ID by reading the levels at ports PC0 
– PC7. Connections JU0852/3/4 are provided by the individual keypads.
The MODB / MODA input of the µP must be at a logic 1 for it to star t executing correctly. The XIRQ 
and the IRQ pins should also be at a logic 1.
Voltage sense device U0832 provides a reset output that goes to 0 volts if the regulated 5 volts goes 
below 4.5 volts. This is used to reset the controller to prevent...

Theory of Operation2-39
The keypad back light current is drawn from the FLT A+ source and controlled by transistor Q0933. 
The current flowing through the LED’s cause a proportional voltage drop across the parallel resistors 
R0947, R0948. This voltage drop is amplified by the op-amp U0931-2. U0931-2 and Q0934 form a 
differential amplifier. The voltage difference between the base of Q0934 and the output of U0931-2 
determines the current from the base of the LED control transistor Q0933 and in turn the...

2-40Theory of Operation
The two A/D converter inputs (J0811-9/10) are used as a microphone with keypad. A pressed key 
changes the dc voltage on both lines. The voltages depend on which key is pressed. The µP 
determines, from the voltage on these lines, which key is pressed and sends this information to the 
host radio.
Line PTT IRDEC (J0811-6) is used to key up the radio’s transmitter. While the PTT button on a 
connected microphone is released, line PTT IRDEC line is pulled to a +5 volts level by...

3-1
Chapter 3
Maintenance
3.1 Introduction
This chapter of the manual describes:
nPreventive maintenance
nSafe handling of CMOS and LDMOS devices
nRepair procedures and techniques
3.2 Preventive Maintenance
The radios do not require a scheduled preventive maintenance program; however, periodic visual 
inspection and cleaning is recommended.
3.2.1 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...

3-2Maintenance
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. Upon completion of 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.
3.3 Safe Handling of CMOS and LDMOS
Complementary metal-oxide semiconductor (CMOS) devices are used in this family of radios. CMOS 
characteristics make them...

Maintenance3-3
The printed-through holes may interconnect multiple layers of the printed circuit. Therefore, care 
should be exercised to avoid pulling the plated circuit out of the hole.
When soldering near the 20-pin and 40-pin connectors:
nAvoid accidentally getting solder in the connector.
nBe careful not to form solder bridges between the connector pins.
nClosely examine your work for shor ts due to solder bridges.
nDo not exceed 210 degrees C when reworking boards.
nDo not exceed 5 degrees...

3-4Maintenance
To replace a chip component using hot air:
1. Use the hot-air hand piece and reflow the solder on the solder pads to smooth it. For components 
having two or three solder connections, apply a dot of NO-CLEAN solder paste to the lead joints 
before removal.
2. Apply a drop of solder paste flux to each pad. For dual leaded devices such as SOICs, TSOPs, 
and quad leaded devices less than 20 leads, such as PLCCs and QFPs, apply a bead of solder 
paste.
3. Using a pair of tweezers, position the...

Maintenance3-5
3.5 Recommended Test Tools
Table 3-1 lists the recommended tools used for maintaining this family of radios. These tools are also 
available from Motorola.
Table 3-1.  Recommended Test Tools
Motorola Part
Number DescriptionApplication
RSX4043 Torx Driver  Tighten and remove chassis screws
6680387A70T- 6  To r x  B i tRemovable Torx driver bit
WADN4055A
6604008K01
6604008K02Portable soldering station
0.4mm replacement tip
0.8mm replacement tipDigitally controlled soldering Iron
For...

3-6Maintenance
3.6 Transmitter Troubleshooting Chart
No
Is Q4441 OK ?
Ye s
Is drive from VCO
        >+4dBm? NoIs voltage drop across
     R4497 >4.5V ?No
Check Q4431 gate(open)
and drain resistances
            (11kohm)NoCheck Q4421 gate(open)
and drain resistances
             (11kohm)No
        Check
PCIC_MOSBIAS_1
NoNo
Change
Q4573 
              START
        No power
  
  Is Vctrl
there? Is Q4573
   OK?
Check voltage
on pin 4 U4501
Check voltage
on pin 5 U4501
Check R4422-5
and go back to top...