Motorola XTS 2500 Service Manual page 188

6.1-22
6.1.23VHF Transmitter RF Troubleshooting Chart
No/Low TX Power
Is
Yes
TX current
>300mA?
No
No
Is B+
at L125?
Yes
Is B+ at
No
U101 pins 6,7,
and 14?
Yes
*
Is Vdc
No
at TP_146
>2V?
Yes
*
Is Vdc
No
at U101 pin 1
>2V?
Yes
*
Is Vdc
No
at R103
>1V?
Yes
*
Is
No
RF at U101
pin 16 >2
dBm?
Yes
*
Is
No
RF at U101
pin 6 >20
dBm?
Yes
Check L125, C124,
C125, L126, C126,
L127, C127
and C128
February 14, 2012
VHF Troubleshooting Charts: VHF Transmitter RF Troubleshooting Chart
*
Is RF
input drive at
U101 pin 16
>2dBm?
No
Go to Frequency
Generation Unit
Chart
Check E140,
L119
Check E102,
L114
For Analysis, shields SH103 and SH104 need to be removed.
Check ALC IC
Check R108
Replace Q198
Go to Frequency
Generation Unit
Chart
Check C106,
Replace U101
C181 and L101
*
Is
voltage drop
across D170
>0.5V?
No
Check U102
and the ALC IC
= Transmitter enable Low.
*
MAEPF-27349-O
*
Is
Yes
there RF
at connector
J101?
No
Check C177, C174,
L172, C175, C172,
L171, C173, L170,
C170 and C171
Remove SH1
and Check
D171
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