Motorola APX 1000 - Page 805

Troubleshooting Charts: PA Failure 5-49
PA Failure – Page 4 (ALC)
Remove SH15 and measure
PA control voltage at
U901 for VHF,
U1601 for UHF1/UHF2 and
U1001 for 700/800 MHz
pin 4
5
VC_OFFSET low,
remove SH6
Is U901/U1601/U1001/
Pin 1 about 2.5V?
Replace U901/U1601/U1001
Yes
Is U1202 Pin 5 about
2.3+/-0.2V?
Replace U1202
Yes
No
Is U1251 Pin 1
about 2.3+/-0.2V?
Replace U1251
Yes
No
Is U1282 Pin 6
about 2.3+/-0.2V?
Replace U1282
Yes
No
Is U1269 Pin 3
about 2.3+/-0.2V?
Yes
No
Is U1269 Pin 1
ANA_CTRL_ISET
about 5V?
U1269 is a smaller picker. If Pin 1 measured voltage was
lower than Pin 3, Pin 1 voltage will be picked as V-control
and caused no or low V_control to bias PA, resulting no
or low TX power
Yes
MAKO Ramp is working fine
Is U1253 Pin 1
about 2.3+/-0.2V?
No
Replace U1253
Yes
Is U1201 Pin 1
about 5V at DAC 4095?
No
Replace R1244
Yes
No
Replace U1201