Kenwood NX-3720HG Service Manual page 161

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