Measure TX current
at UHF1/UHF2
test frequencies
Yes
No
1
Measure DC voltage
at pin 4 of U1601
Yes
Is current less
than 350mA?
Measure voltage at
pin 5 of U1601
Replace Q1601
Yes
No
Is current
approximately
500mA?
Yes
No
Is voltage
approximately 6V
at DAC=4095?
Is current greater
than or close to
2A?
Use a spectrum
analyzer and high-
impedance RF
probe. Measure
RF_IN_1 at C1601.
Yes
Yes
Is the frequency
correct?
No
See FGU
troubleshooting
charts
Yes
Is the power
level about 3 dBm?
No
See FGU
troubleshooting
charts
Measure power at
C1625
Yes
Is the power
approximately
37 dBm?
No
Replace Q1601
Measure power at
C2604
Is the power
approximately
37 dBm?
No
Check D2603
positive node
voltage
Measure power at
C1822
Is the power
approximately
37 dBm?
Check power out at
C1122 and any
process issue
Yes
Is the voltage
near 7.0V?
No
Replace D2603
Yes
Check pin 3 and
pin 2 of Q2601
Is pin 3 of
Q2601=Raw B+
and pin 2=3.0V
No
Replace Q2601
Yes
Check continuity of
R2605 and L2602
Measure voltage at
pin 3 of Q1101
Yes
No
Is voltage
approximately
7V?
Yes
No
Is voltage
approximately
0V?
Replace U1601
Replace Q1103
Measure voltage at
pin 1 of Q1101
Yes
No
Is voltage greater
than 1.5V?
Replace Q1101
5
Measure DC voltage
at pin 5 of U1601
Was voltage
near 7.5V?
Measure voltage at
pin 1 of Q1101
No
Yes
With the radio in RX
mode, measure the
DC voltage on both
pins of L1603
Was voltage
near 7.5V on
both sides?
No
Yes
Is there 7.5V
on C1608?
No
Check E1101 for
solderability issues and
replace as necessary
Yes
Check L1603 for
solderability issues and
replace as necessary
Was voltage
near 3V?
No
Measure the logic
inputs of TXH_1
from R1111 and
TX_INH from U1138
Yes
Trace voltages and check for solderability
issues on R1102, Q1101, and Q1103.
Replace parts as necessary.
With the radio in RX
mode, measure the
DC voltage on the
drain of Q1601
Was voltage
near 7.5V?
No
Check L1606 under shield
SH1 for solderability
issues and replace as
necessary
With the radio in RX
mode, measure the
resistance on the
node shared by
C1616 and R1605
Yes
Is the resistance
near 9.4 kOhms?
No
Check resistors R1601,
R1602, R1603, R1604,
and R1605 for resistance
and solderability issues
and replace as necessary
In TX mode,
measure the voltage
on pin 4 of U1601
Yes
If resistance is very low, in the
100’s of ohms, and there are no
issues with the resistors then
there is a gate short on the PA.
Clear short or replace Q1601.
Is the voltage
near 6V?
Yes
Is TX current just
above standby
current?
Yes
Is the TX current
between 300 and
900mA?
Yes
Is the TX current
above 900mA?
Yes
Is the voltage
below 4V?
Yes
The PA and Driver are
likely damaged. Replace
Q1601 and U1602.
The PA is likely
damaged. Replace
Q1601.
Lift shield SH1 and check
for solderability or part
issues on all 900 series
parts. Replace parts as
necessary.
If no issues found, lift shield
SH8 and check for solderability
or part issues on all 1200
series parts. Replace parts as
necessary.
5
If the voltage is between 4 and 5.5V then
the control loop should be working and
power should be available. Check D2603
positive node voltage.
No
Is the voltage
near 7.0V?
Yes
No
Check pin 3 and
pin 2 of Q2601
Is pin 3 of
Q2601=Raw B+
and pin 2=3.0V
Yes
No
Check continuity of
R2605 and L2602
Replace Q2601
Replace D2603
To Next Page
Loading...
