(No.RA054<Rev.001>)1-161
5.3
Failure diagnosis of the Bluetooth section
Overview:
When the Bluetooth function does not operate, use this flowchart to determine the problem.
No
Pass
Pass
Pass
Pass
Pass
Pass
X2
X1
Major parts for a Bluetooth circuit
TX-RX Unit
BT/GPS Unit
IC404
UART
MPU/DSP
IC
PCM
PCM
Power
UART
IC6
IC5
UART
5.4V
Bluetooth
Antenna
GPS
Antenna
L11
LC
Filter
L9
BPF
32.768kHz
Clock
BT/GPS
IC
PCM
Level
conversion
IC
IC7
Level
conversion
IC
IC2, IC3, IC4
TCXO
19.2MH
1.8V
3.3V
3.3V
Voltage
regulator
Charge the BT headset. Turn on your BT headset and bring it
within one meter.
Try again pair with BT headset.
• Bluetooth antenna (Pattern Antenna)
• LC filter (L11)
• Bluetooth/GPS IC (IC5)
• Level conversion IC (IC6, IC7)
• TCXO 19.2MHz (X1)
• 32.768 kHz clock (X2)
• 33BT Regulator (IC3)
• 18BT Regulator (IC2)
• MPU/DSP IC (IC404: TX-RX Unit)
I can not pair with the Bluetooth (BT) headset.
Is the BT headset charged enough?
Is the BT headset turned on?
Is the BT headset in pairing mode?
Check the BT/GPS UNIT PCB side A.
Check the BT/GPS UNIT PCB side A.
Fail
Verify the antenna matching
parts.
Visually check to L15, C68
Verify the BT/GPS power
supply.
(33BT) L4: 3.3V
Fail
Verify the BT/GPS power
supply.
(18BT) L5: 1.8V
Fail
Fail
Verify the RTC for the
BT/GPS.
X2 (3 pin): Square waveform,
32.768 kHz, 1.8Vp-p
Replace any abnormal parts.
[The BT/GPS power supply
Fail
line 33BT circuit is faulty]
Verify the PCB side A parts.
L4, C15, C19, C20, C33
Replace any abnormal parts.
Check the BT/GPS UNIT
PCB side B (a).
Check the BT/GPS UNIT
PCB side B (b).
Fail
[The BT/GPS power supply
line 18BT circuit is faulty]
Verify the PCB side A parts.
C18, C13, C31, L8, C39
Replace any abnormal parts.
Verify the RTC line circuit for
the BT/GPS.
X2, L8, C39
Replace any abnormal parts.
Summary of Contents for NX-3720
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