Motorola Astro Digital Mobile Radio Xtl5000 Detailled 6881096c74 B Manual

							6881096C74-BMay 25, 2005
Troubleshooting Charts: Flowcharts5-21
5.6.7 Low or No RX Injection Signal (136–174 MHz)
Figure 5-11.  Low or No RX Injection Signal (136–174 MHz)

	





 



	



    
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							May 25, 20056881096C74-B
5-22Troubleshooting Charts: Flowcharts
5.6.8 Low or No TX Injection Signal (136–174 MHz)
Figure 5-12.  Low or No TX Injection Signal (136–174 MHz)

		


 
 
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							6881096C74-BMay 25, 2005
Troubleshooting Charts: Flowcharts5-23
5.6.9 TX or RX VCO Unlock (Fail 001) (136–174 MHz)—Part 1 of 2
Figure 5-13.  TX or RX VCO Unlock (Fail 001) (136–174 MHz)—Part 1 of 2

	



  
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							May 25, 20056881096C74-B
5-24Troubleshooting Charts: Flowcharts
5.6.10 TX or RX VCO Unlock (Fail 001) (136–174 MHz)—Part 2 of 2
Figure 5-14.  TX or RX VCO Unlock (Fail 001) (136–174 MHz)—Part 2 of 2

	


  
  

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							6881096C74-BMay 25, 2005
Troubleshooting Charts: Flowcharts5-25
5.6.11 No Output Power at TX Mode (136–174 MHz)
Figure 5-15.  No Output Power at TX Mode (136–174 MHz)


    
	


  

	


 
  
 

    


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							May 25, 20056881096C74-B
5-26Troubleshooting Charts: Flowcharts
5.6.12 No Output Power and IDC < 2A at TX Mode (136–174 MHz)
Figure 5-16.  No Output Power and IDC < 2A at TX Mode (136–174 MHz)


 

	
 




  
 
   
     

  
 	


 
 
 	
  

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							6881096C74-BMay 25, 2005
Troubleshooting Charts: Flowcharts5-27
5.6.13 No 16.8 MHz Reference Oscillator Frequency (380–470 MHz and 450–520 MHz)
Figure 5-17.  No 16.8 MHz Reference Oscillator Frequency (380–470 MHz and 450–520 MHz)
U5751DC Voltages
Pin 1
Pin 2
Pin 3
Pin 4
Pin 5No connection
1.5
Ground
1.5
3
>800mVpp
16.8MHz? Probe pin 3
of Y5750 for
16.8MHzSTART
No 16.8MHz
Reference
No
Ye s
>800mVpp
at pin 23
U5752?No
Ye sCheck
C5761Replace
Y5750 3.0VDC
at pin 4 of
Y5750?No
Ye sCheck 3.0V
regulator path
from U5750
>500mVpp
at pin 2
U5751?No
Ye sCheck C5760
and R5763
>3.0Vpp
at pin 4
U5751?No
Ye sCheck
U5751
>1.4Vpp
at TP5791?NoCheck L5753,
C5768, C5763,
R5768 and C5767Measure 16.8MHz Signals
with Oscilloscope having a
bandwidth >100MHz.
NOTE:  L5753 and C5768 filter the
distorted output of U5751 resulting
in a clean sinusoidal 16.8MHz signal.
R5768 and C5763 adjust the amplitude. 
						

							May 25, 20056881096C74-B
5-28Troubleshooting Charts: Flowcharts
5.6.14 Poor RX Sensitivity or No RX Audio (380–470 MHz and 450–520 MHz)—Part 1 
of 2
Figure 5-18.  Poor RX Sensitivity or No RX Audio (380–470 MHz and 450–520 MHz)—Part 1 of 2
 Poor Rx
Sensitivity or no
Rx audio
Measure Transceiver
12dB Sinad by injecting
signal at antenna portYe s
Ye s3kHz FM Deviation
1kHz Audio  tone
12 dB Sinad
Sensitivity
< - 117.5 dBm Std.

						

							6881096C74-BMay 25, 2005
Troubleshooting Charts: Flowcharts5-29
5.6.15 Poor RX Sensitivity or No RX Audio (380–470 MHz and 450–520 MHz)—Part 2 
of 2
Figure 5-19.  Poor RX Sensitivity or No RX Audio (380–470 MHz and 450–520 MHz)—Part 2 of 2
1
Inject a standard FM test
signal into the antenna port.
Use a spectrum analyzer and
high-impedance RF probe to
measure the signal at TP5301

						

							May 25, 20056881096C74-B
5-30Troubleshooting Charts: Flowcharts
5.6.16 RX IF—Poor SINAD or No Audio (380–470 MHz and 450–520 MHz)—Part 1 of 2
Figure 5-20.  RX IF—Poor SINAD or No Audio (380–470 MHz and 450–520 MHz)—Part 1 of 2
Level
is -3dB
referenced to 
R5412?No
No No Ye s
Measure the IF
signal level
(109.65MHz)
at C5403 Measure the IF
signal level
(109.65MHz)
at C5406
Check Y5400
Level
is +20dB
relative to the RF
input level
at C5406?No
Ye s
Voltage
level of 9.0V 
at R5404? 
Ye s
Voltage
level of
0.7V at Q5401
Base
(pin 1)?
Ye s Measure the DC
Bias voltage level
on transistor
Q5401
Replace
Q5401 Inspect biasing
components and
check Voltage
Regulator U0950 for
 normal operation
Inspect crystals and
matching networks for
missing components
and/or soldering defects 1