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Motorola Radius Cm200 Cm300 Pm400 Detailed 6881098c00 A Manual

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    							Receive Signalling Circuits2-21
    9.4 Handset Audio
    Certain handheld accessories have a speaker within them which require a different voltage level 
    than that provided by U502. For these devices HANDSET AUDIO is available at control head 
    connector J2 pin18.
    The received audio from the output of the ASFIC CMP’s digital volume attenuator is routed to U505 
    pin 2 where it is amplified. This signal is routed from the output of the op-amp U505 to J2-pin 18. 
    From the control head, the signal is sent directly to the microphone jack. 
    9.5 Filtered Audio and Flat Audio
    The ASFIC CMP output audio at U504-pin 39 is filtered and de-emphasized, but has not gone 
    through the digital volume attenuator. From ASFIC CMP U504-pin 39 the signal is routed via R5034 
    through gate U509-pin 12 and AC coupled to U505-pin 6. The gate controlled by ASFIC CMP port 
    GCB4 selects between the filtered audio signal from the ASFIC CMP pin 39 (URXOUT) or the 
    unfiltered (flat) audio signal from the ASFIC CMP pin 10 (UIO). Resistors R5034 and R5021 
    determine the gain of op-amp UU505-pin 6 for the filtered audio while R5032 and R5021 determine 
    the gain for the flat Audio. The output of U505-pin 7 is then routed to P1 pin 11 via DC blocking 
    capacitor C5003. Note that any volume adjustment of the signal on this path must be done by the 
    accessory.
    10.0 Receive Signalling Circuits
    Figure 2-10 Receive Signalling Paths
    10.1 Sub-Audio Data (PL/DPL) and High Speed Data Decoder
    The ASFIC CMP (U504) is used to filter and limit all received data. The data enters the ASFIC CMP 
    at input DISC (U504 pin 2). Inside U504 the data is filtered according to data type (HS or LS), then it 
    is limited to a 0-3.3 V digital level. The MDC and trunking high speed data appear at U504-pin 19, 
    where it connects to the µP U403 pin 80.
    DET AUDIO
    DISCRIMINATOR AUDIO
    FROM RF SECTION
    (IF  IC)19
    18
    25
    2
    82
    80
    DISC
    PLCAP2LSIO HSIO DATA FILTER
    AND DEEMPHASISLIMITER
    FILTER
    LIMITERASFIC_CMP
    U504
    MICRO
    CONTROLLER
    U403
    85 44
    8 PLEAP 
    						
    							2-22THEORY OF OPERATION
    The low speed limited data output (PL, DPL, and trunking LS) appears at U504-pin18, where it 
    connects to the µP U403-pin 80.
    The low speed data is read by the µP at twice the frequency of the sampling waveform; a latch 
    configuration in the ASFIC CMP stores one bit every clock cycle. The external capacitors C5028, 
    and C5026 set the low frequency pole for a zero crossings detector in the limiters for PL and HS 
    data. The hysteresis of these limiters is programmed based on the type of received data.
    10.2 Alert Tone Circuits
    When the software determines that it needs to give the operator an audible feedback (for a good 
    key press, or for a bad key press), or radio status (trunked system busy, phone call, circuit failures), 
    it sends an alert tone to the speaker. It does so by sending SPI BUS data to U504 which sets up the 
    audio path to the speaker for alert tones. The alert tone itself can be generated in one of two ways: 
    internally by the ASFIC CMP, or externally using the µP and the ASFIC CMP.
    The allowable internal alert tones are 304, 608, 911, and 1823 Hz. In this case a code contained 
    within the SPI BUS load to the ASFIC CMP sets up the path and determines the tone frequency, 
    and at what volume level to generate the tone. (It does not have to be related to the voice volume 
    setting.)
    For external alert tones, the µP can generate any tone within the 100-3000 Hz audio band. This is 
    accomplished by the µP generating a square wave which enters the ASFIC CMP at U504 pin 19. 
    Inside the ASFIC CMP this signal is routed to the alert tone generator.
    The output of the generator is summed into the audio chain just after the RX audio de-emphasis 
    block. Inside U504, the tone is amplified and filtered, then passed through the 8-bit digital volume 
    attenuator, which is typically loaded with a special value for alert tone audio. The tone exits at U504-
    pin 41 and is routed to the audio PA like receive audio. 
    						
    							Chapter 3
    TROUBLESHOOTING CHARTS
    This section contains detailed troubleshooting flowcharts. These charts should be used as a guide in 
    determining the problem areas. They are not a substitute for knowledge of circuit operation and 
    astute troubleshooting techniques. It is advisable to refer to the related detailed circuit descriptions 
    in the theory of operation sections prior to troubleshooting a radio.
    Most troubleshooting charts end up by pointing to an IC to replace. It is not always noted, but it is 
    good practice to verify supplies and grounds to the affected IC and to trace continuity to the 
    malfunctioning signal and related circuitry before replacing any IC. For instance, if a clock signal is 
    not available at a destination, continuity from the source IC should be checked before replacing the 
    source IC. 
    						
    							3-2TROUBLESHOOTING CHARTS
    1.0 Troubleshooting Flow Chart for Receiver RF (Sheet 1 of 2)
    Problem in 12 KHz and 
    25 KHz channel spacing
    9V on
    R310 (LNA)
    OK
    ?Check
    RX_ENNoGo to 
    DC Section
    Ye s
    RX_EN
    ON ?NoCheck Q306, Q300 
    and U403Ye s
    START
    LOC_DIST
    ON
    ?Check Q304, D305 
    and U403
    LO
    POWER
    OK ?
    Go to SYN 
    Section
    Ye s
    Ye s No
    No
    Go
    to A
    3 V
    to U301
    Okay ?No
    Check
    LOC_DIST
    Go to
    DC Section
    Ye s
    Check D301-304
    Replace IF Filters( FL304, FL301
    If problem in 25 KHz spacing
    Check
    TPI
    Check 5V
    on R337 (UHF),
    R336 (VHF)
    5V
    (IF AMP)
    OK ?Go to 
    DC SectionYe s NoCheck 3V
    on R339  
    						
    							Troubleshooting Flow Chart for Receiver RF (Sheet 1 of 2) 3-3
    1.1Troubleshooting Flow Chart for Receiver (Sheet 2 of 2)
    3V
    (IFIC -Vcc)
    OK ?
    Installation
    OK ?
    Ye s
    Ye s No
    No
    A From
    Check visually
    FE and BE
    components
    installation ?
    Inject - 40dBm (CW)
    to RF connector
    Check Power on
    C335 (UHF) C332 (VHF)
    RF
    Power
    > -28 dBM
    ?Ye s NoCheck Power on
    C337 (UHF),
    C336 (VHF)
    Go to 
    DC Section
    Check 
    the component
    FE Problem
    Replace 
    Q303, Q301
    Check passive
    componentsRF
    Power
    > -28 dBM
    ?Ye s
    NoReplace 
    Q305, Q300, U302
    Check passive
    componentsCheck Y301
    44.395 MHz
    Y301
    OK
    ?Ye s NoReplace Q302, Y300
    Check D301 - 304
    Replace Y301
    3V to
    U301
    OK
    ?Ye s No
    Replace U300Go to DC Section 
    						
    							3-4TROUBLESHOOTING CHARTS
    2.0 Troubleshooting Flow Chart for 40 W Transmitter (Sheet 1 of 3)
    START
    Ye s
    No
    Check components between 
    Q100 and RF output, 
    Antenna Switch D104, 
    D103, VR102 and Q106
    No or too low power when keyed
    Current
    increase when 
    keyed?
    Check power settings, tuning 
    & components between U103 
    Pin 3 and ASFIC Pin 6 before 
    replacing ASFIC
    Control 
    Voltage at 
    TP150
    >4Vdc?Check PA 
    Stages
    >4A
    Voltage U103 
    pin 5 = 
    4.7V?
    U103 Pin 3 
    1.8Vdc
    Check 9.3V 
    Regulator 
    U501
    Ye s
    Ye sNo
    No
    Ye sCheck 
    U103
    Check forward 
    Power Sense 
    Circuit
    No
    Short U100 
    Pin 3 to 
    ground
    Voltage at 
    TP150 rises?Check PA 
    Stages
    Check Forward 
    Power Sense 
    Circuit
    Ye s
    No >500mA & 
    						
    							Troubleshooting Flow Chart for 40 W Transmitter (Sheet 1 of 3) 3-5
    2.1Troubleshooting Flow Chart for 40 W Transmitter (Sheet 2 of 3)
    No
    Ye s
    Ye sNo
    Check bias tuning 
    before replacing 
    U504
    Check PA 
    Stages
    No or too low power when keyed
    DC
    Voltage
    at Q101 & Q102 
    base=0?
    DC
    Voltage
    at U103 
    Pin 8
    Check U510
    Check resistive network at 
    Pin 9 and 10 of U103 
    before replacing U101
    Measure DC Voltage at Pin 2 & 3 of U5401
    Pin 2 
    Voltage 
    0.62 x Voltage 
    at Pin 1
    Replace U5410
    Pin 3 
    Voltage 
    0.51 x Voltage 
    at Pin 1
    Replace U5410
    DC 
    Voltage at 
    PA_CURRENT 
    line?
    Replace Q105
    Check Final PA Stages
    ASFIC
    U504 
    Pin 5 2-3V
    Check components be-
    tween ASFIC and Q105 
    before replacing Q105
    DC 
    Voltage at 
    U103 Pin 
    10=8.9V
    Check Q102, 
    Q101, R122, R165
    Check U103 and Resistive 
    Network at Pin 10 of U103 
    before replacing U101
    No
    No
    Ye s
    >5V
    2 to 5V
    Ye s
    Supply Voltage
    2-3V
    Ye s No
    0V
    						
    							3-6TROUBLESHOOTING CHARTS
    2.2Troubleshooting Flow Chart for 40 W Transmitter (Sheet 3 of 3)
    No
    Ye s
    Ye sNo
    Check Final PA Stage
    PA_Bias 
    Voltage at 
    R134
    RF Voltage 
    after C1044 
    >100mV?
    Voltage 
    across R122 
    >2V?
    RF Voltage 
    Q105 gate 
    >1V?
    RF Voltage 
    Q100 gate 
    >7V?
    Check components 
    between Q100 & 
    antenna connector
    Replace Q100
    Check FGU (U5301)
    Check components 
    between C1044 & 
    C1117
    Check components 
    between C117 & 
    Q105
    Check components 
    between Q105 & 
    Q100
    No
    No Ye s Ye s 1-4VSupply Voltage
    Check components 
    between ASFIC & 
    Q100 before re-
    placing Q100
    RF Voltage 
    after C1044 
    >100mV?
    Check Bias Tuning 
    before replacing
    ASFIC U504
    Ye s
    No0V 
    						
    							Troubleshooting Flow Chart for Synthesizer3-7
    3.0 Troubleshooting Flow Chart for Synthesizer
    5V
     at pin 6 of 
    D200
    Is
    information
    from
     uP U403
    correct
    ?
    Is
    U200 Pin 47
    at = 14.6VDC
    ?
    Is
    U201 Pin 19
    4.5 VDC in TX?  
    (at VCO section)
    ?
    Sta rt
    Visual 
    check of the 
    Board
    OK?Correct
    Problem
    Check 5V
    Regulator
    U503
    +5V
    at U200
    Pin’s
    13 & 30
    ?
    Is
    16.8MHz
    Signal at U200 
    Pin 19
    ?
    Check
    Y201 and associated 
    Parts
    Are
    signals
    at Pin’s 14 &15 
    of U200
    ?
    Check 
    R228Check R201
    Is
    U200
    Pin 2  >4.5 VDC in 
    Tx & 
    						
    							3-8TROUBLESHOOTING CHARTS
    4.0 Troubleshooting Flow Chart for VCO
    Are Q200
    Base at 2.9V 
    Collector at 6.6V 
    Emitter at 2.2V
    Are U201 Pins
    15 at 1.0V
    10 at 3.9V
    16 at 1.8V
    Low or no RF Signal
    at TP1
    Visual check
    of board
    OK?
    370mV DC at
    U201 Pin 19
    NO
    YES
    at base of Q200
    NO
    NO
    NO YES
    YESYESLow or no RF Signal
    at input to PA
    4.5V DC at
    U201 Pin 19
    Is RF available 
    at C2060
    YES
    YESYES YES NO
    NO
    NO
    NO
    NO
    Audio =180mVRMSat “-” Side of 
    4.5VDC
    at D205
    If R211 and R12 are OK,
     then replace D205
    Replace R211
    Replace R212
    NONO
    YES
    YES
    If parts between  
    R109 & U201 Pin10
    are OK, replace U201
    TX VCO
    RX VCO
    Correct
    ProblemVisual check
    of board
    OK?
    Check runner 
    between U200 Pin 2 
    and U201 Pin 19
    Is RF available 
    Replace U201
    If all parts associated 
    with the pins are OK, 
    replace Q200
    If all parts from collector
    of Q200 to TP1 are
    OK, replace Q200
    Power OK but 
    no modulation
    Check parts to pre-driver
    If all parts 
    associated 
    with the pins 
    are OK, 
    replace U201
    YESYES
    Make sure Synthesizer is 
    working correctly and runner 
    between U200 Pin 28 and 
    U201 Pin 14 & 18 is OK 4.5V DC 
    OK ?
    OK?
    OK?
    D205  at U201 Pin 14 & 18    4.5V DC 
    OK ? at U201 Pin 14 & 18    
    NO 
    						
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