5.17 Gps Failure - Motorola APX 1000 Detailed Service Manual

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5.17 GPS Failure

for 32 kHz output, and pin D12 (IO91)
Radio firmware
was corrupted
Replace faulty
regulator
Replace Y1304
Verify the location feature is enabled,
replace antenna, and retry in a strong
signal environment (open sky)
Check for 32 kHz clock at R1318, and
Check U6101 (CPLD) pin E2 (IO74)
for 1.8V on reset.
Verify communication with GPS IC by resetting radio while probing TP1307 and
TP1308 with an oscilloscope. Activity should be seen on both UART test points
Re-flash radio with the latest
released firmware
Yes
GPS lock?
No
Remove Main board shield and check
VBAT voltage for 3.5V (measured at R1313),
and VDDS for 1.8V (measured at R1315)
No
Regulators
OK?
Yes
Check for 26 MHz at C1321
No
Is 26 MHz
present?
Yes
Replace GPS IC U1301
START
No GPS Lock
The GPS receiver requires a working
Yes
antenna, and a direct view of the sky
GPS lock?
in order to achieve a position fix
No
1.8V for GPS reset at TP1306
No
32 kHz and
reset ok?
Yes
for successful comm.
No
Yes Remove Main board shield and
Comm.
check regulator U1305 for 2.8V
successful?
(measured at C1303)
Check for 1.8V on LNA enable
measured at C1309
Measure the GPS total front-end gain @ 1575.42 MHz while
GPS IC is active (measured from antenna port to C1324).
Total gain should be approximately 16dB.
Replace GPS IC U1301
Troubleshooting Charts: GPS Failure
No
Replace faulty
Regulator
regulator
OK?
Yes
No
Replace GPS IC U1301
1.8V?
Yes
Debug front-end for faulty
No
component (LNA - U1304,
~18 dB?
and SAW filters - FL1301
and FL1303)
Yes