Troubleshooting Flow Chart For 35 W Power Amplifier - Motorola M11URD6CB1_N Service Manual

GTX LTR/Privacy Plus 800 MHz Mobile Service Manual
No
Go to synthesizer
troubleshooting.
35 W PA RF SECTION FAULT
No
Check CR6501, Q6506,
Q6501, L6503, L6502.
Check U6502, R6520,
No
L6519, L6504 ,L6505,
L6506,VR6501.
No
Replace U6501.
output ~24 dBm?
No
Check C6555, CR6502,
CR6503, Q6505
No
Check H6502. L2,L3,L4.
.
Replace Antenna
connector.
June, 2000
Yes
Yes
No
Is PA control
at ~0V?
Is TX_INJ Is there 5V at
> 2 dBm?
PA_ENABLE?
Yes
there ~2V
Is RF at
at U702-2
U6501
PA_PWR_SET
~2 dBm?
Yes
Are voltages
Is there ~ 0V at
at U6501*
U701-7?
OK?
Yes
Is RF
at U6501
U701-14
at <4.5V?
Yes
Is RF after
U701-1
Tx switch
at <4.5V?
at ~24 dBm?
Yes
Is RF after
U701-10
Harmonic Filter
~4.6V?
at ~29 dBm?
Yes
Faulty integrator.
Replace U701.
START
No
Is Red LED on?
Is control head
OK?
Yes
Yes
Is K9.1 OK?
Yes
Go to controller
troubleshooting.
No
PA LOGIC SECTION FAULT
Is
No
Faulty power setting DAC
or software
?
Yes
Faulty coupler.
No
Check CR6509, R6515,
CR6506, R6514, L6516,
R6512.
Yes
Is
Check R6519, U701,
No
L6515, R725, R0721,
R722, R723.
Yes
Faulty current sense
Is
No
mechanism. Check
R6520, U701 DAC
(U702-11).
Yes
Is
Faulty REF voltage.
No
Check R251, R252,
U251.
Yes
6880905Z99-O
Troubleshooting
Troubleshooting Charts
Go to
No
control head
troubleshooting.
Is there
No No Go to controller
5V at
troubleshooting.
K9.1_ENB?
Yes
Is there
No
Replace
9.3V at Q741
Q741 and Q742.
or Q742?
Yes
Go to
synthesizer
troubleshooting.
Levels were measured with an
RF probe in series with 0.5pF
capacitor.
*U6501 DC voltages:
Pins 3 and 4: A+ +/10.1V
Pin 2: 9.1V (during Tx only)
Troubleshooting Flow Chart
for 35 W Power Amplifier
9-7