Troubleshooting Flow Chart For Transmitter - Motorola 6864115B62-C Detailed Service Manual

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Troubleshooting Flow Chart for Transmitter

DC
No
Voltage
@Drains of
Q1402 &
Q1403
?
Look for
Yes
short on
Supply Line
DC
No
Voltage
@ Cathode of
D1401 &
D1402
?
Check 9T1 and
Yes
Diode Bias Circuit
AC
Voltages @
No Drains of Q1402 &
Q1403 both sine or
both distorted
?
Verify RF Continuity
to gates of
Yes
Q1402 & Q1403
Check circuitry
between Q1402 &
Q1403 and
Antenna Port
LOW BAND TROUBLESHOOTING CHARTS
> 1A
Check
MOSBIAS_2
MOSBIAS_3
and Feed Networks
START
No or Low
Power Out
Check Pressure Pad
TX
Safety
Switch Circuitry
Switch
< 1A
TX
CURRENT
<<18V pp
RF @
Junction
R1413 &
R1414
>18V pp
No
DC
Voltage
@ TP1402 &
TP1403
?
Yes
Check DC/AC
Gate Circuits of
Q1402 & Q1403
Chapter 3
and/or
DC
No
Voltage
@ Gate of
Q1401
?
Yes
AC
Voltage
Yes
@ Gate of
Q1401
?
No
DC
Yes
Voltage
@ U1401
?
No
Check Supply Feed
and/or PowerControl
Circuits.
Check
MOSBIAS_1
Supply and
Feed Network
Check
Q1401
Device
Check
U1401
Device