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UHF3 (350
–
400 MHz)
Troubleshooting Flow Chart
31
[4] The output voltage of U905 and U909 is 5 V and 3.3 V respectively.
[5] The output voltage of U902 is 5 V.
[6] The output voltage of U900 and U901 is 3.3 V.
[7] The output voltage of U903 is 1.8 V.
[8] The output voltage of U919 is 1.6 V.
6.2
GPS Circuit
Check the GPS
circuit
Positioning is
normal?[1]
RX signal is weak?[2]
Yes
No
Peripheral
components are
properly connected
and soldered?
Replace defective
components
Yes
Yes
Antenna is damaged?
No
GPS circuit is
normal
Replace GPS
module U326
Yes
Replace the active
antenna
No
SiRF Demo software
displays
communication status
on the computer?
Voltage at SMA of
GPS antenna
connector is normal?
[3]
Yes
Yes
Change active
antenna
Check and replace
connector W321
No
No
Voltage of U901 is
normal?
[4]
No
Check UART port
Yes
Replace U901
Check front-end
circuit
R368 and R370 works
normally?
[5]
Re-solder
R368 and R370
Replace GPS
module U326
Yes
No
No
Description of normal situations:
[1] The satellite signal is received properly.
[2] The sensitivity is less than -130 dBm.
[3] Voltage at SMA of GPS antenna connector ranges from 3.2 to 3.35 V.
[4] The output voltage of U901 is 3.3 V.
Содержание MD78X
Страница 1: ...DIGITAL MOBILE RADIO SERVICE MANUAL...
Страница 5: ...UHF1 400 470 MHz...
Страница 14: ...UHF1 400 470 MHz Exploded View and Packing Guide 7 3 2 Packing Guide...
Страница 56: ...UHF1 400 470 MHz Interface Definition 49 Pin No Name Description 39 GND Grounding 40 PWB_IN Power On Off signal...
Страница 62: ...55 9 PCB View MD78X MD78XG PCB View Front Panel Top Layer...
Страница 63: ...56 MD78X MD78XG PCB View Front Panel Bottom Layer...
Страница 64: ...MD78X MD78XG PCB View Main Board Top Layer 57...
Страница 65: ...MD78X MD78XG PCB View Main Board Bottom Layer 58...
Страница 111: ...UHF2 450 520 MHz...
Страница 120: ...UHF2 450 520 MHz Exploded View and Packing Guide 7 3 2 Packing Guide...
Страница 167: ...54 9 PCB View MD78X MD78XG PCB View Front Panel Top Layer...
Страница 168: ...55 MD78X MD78XG PCB View Front Panel Bottom Layer...
Страница 169: ...MD78X MD78XG PCB View Main Board Top Layer 56...
Страница 170: ...MD78X MD78XG PCB View Main Board Bottom Layer 57...
Страница 216: ...UHF3 350 400 MHz...
Страница 225: ...UHF3 350 400 MHz Exploded View and Packing Guide 7 3 2 Packing Guide...
Страница 272: ...54 9 PCB View MD78X MD78XG PCB View Front Panel Top Layer...
Страница 273: ...55 MD78X MD78XG PCB View Front Panel Bottom Layer...
Страница 274: ...MD78X MD78XG PCB View Main Board Top Layer 56...
Страница 275: ...MD78X MD78XG PCB View Main Board Bottom Layer 57...
Страница 321: ...UHF5 806 941 MHz...
Страница 330: ...UHF5 806MHz 941MHz Exploded View and Packing Guide 7 3 2 Packing Guide...
Страница 376: ...53 9 PCB View MD78X MD78XG PCB View Front Panel Top Layer...
Страница 377: ...54 MD78X MD78XG PCB View Front Panel Bottom Layer...
Страница 378: ...55 MD78X MD78XG PCB View Main Board Top Layer...
Страница 379: ...56 MD78X MD78XG PCB View Main Board Bottom Layer...
Страница 414: ...VHF 136 174 MHz...
Страница 423: ...VHF 136MHz 174MHz Exploded View and Packing Guide 7 3 2 Packing Guide...
Страница 468: ...PCB 52 9 PCB View MD78X MD78XG PCB View Front Panel Top Layer...
Страница 469: ...PCB 53 MD78X MD78XG PCB View Front Panel Bottom Layer...
Страница 470: ...MD78X MD78XG PCB View Main Board Top Layer 54...
Страница 471: ...PCB 55 MD78X MD78XG PCB View Main Board Bottom Layer...