Kenwood NX-3400 Service Manual page 63

5.3 Failure diagnosis of the Bluetooth section
Overview
When the Bluetooth function does not operate, use this flowchart to determine the problem.
BT/GPS IC (IC351)
When the BT/GPS IC is problematic, it is necessary to replace the printed circuit board by the Service Main unit in service. Various
ESN/default adjustment values are written on the service unit. Please refer to "5.6 Replacing Main Unit".
Major parts for a Bluetooth circuit
• Bluetooth antenna (Sheet metal)
• LC filter (L361)
• BT/GPS IC (IC351)
• Level conversion IC (IC352, IC353)
• TCXO 19.2MHz (X401)
• 32.768 kHz clock (X351)
• 32BT Regulator (IC7)
• 18BT Regulator (IC8)
• MPU/DSP IC (IC401)
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?
Yes
Verify the contact of the BT internal antenna with
the PCB. (CN151, CN155, CN353)
Pass
Check the Display Unit PCB
Check the Display Unit PCB
Verify the antenna matching parts.
Visually check to L151, L152, L153, R155, L156,
C158.
Pass
Check the PCB side A.
Check the PCB side A.
Verify the antenna matching parts.
Visually check to R359, C353.
Pass
Verify the BT/GPS power
supply.
(32BT) C34: 3.2V
Pass
IC401
UART
conversion
MPU/DSP
IC
PCM
conversion
X401
TCXO
19.2MHz
No
Fail
Fail
Fail
[The BT/GPS power supply
Fail
line 32BT circuit is faulty]
Verify the parts.
IC7, L8, C33, C34, R9
Replace any abnormal parts.
IC352 IC351
UART
Level
IC
BT/GPS
IC
IC353
PCM
Level
IC
X351
32.768kHz
Clock
Charge the BT headset. Turn on your BT headset and bring it
within one meter.
Try again pair with BT headset.
To reassembly correctly the BT antenna.
If an antenna is defective, replace the BT internal antenna.
Replace any abnormal parts.
Replace any abnormal parts.
Fail
L361 CN353 CN155
LC Bluetooth
Filter Antenna
Sheet metal
CN151
MAIN DISPLAY
UNIT UNIT
Check the PCB
side B (a).
(No.RA070<Rev.001>)1-63