Kenwood KCH-20R Service Manual page 16

5.2 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 (ANT1)
LC filter (L30)
Bluetooth IC (IC12)
Level conversion IC (IC11, IC13)
TCXO 19.2MHz (X1)
32.768kHz clock (X2)
18D Regulator (IC5)
33D Regulator (IC6)
MPU IC (IC14)
I can not pair with the Bluetooth (BT) headset.
Make sure the BT headset have enough power?
Turn on your BT headset?
Put your BT headset into pairing mode?
Yes
Verify the BT power supply.
18D L25 : 1.8V
When a normal
condition is confirmed.
Verify the BT power supply.
33D L24 : 3.3V
When a normal
condition is confirmed.
Verify the 32.768kHz clock for the BT.
X2(3Pin) : Square waveform,
32.768kHz, 1.8Vp-p
When a normal
condition is confirmed.
Verify the BT control signal
(/BT_SHDN).
R132 : BT ON : 1.8V
BT OFF : 0V
When a normal
condition is confirmed.
1-16 (No.RA027<Rev.001>)
IC14
MPU
IC
X1
TCXO
19.2MHz
No
When an abnormal
condition is confirmed. [The BT power supply line
18D circuit is faulty]
Replace the IC5,L4,C47,C49,
R74,R45,R51,L25,L26.
When an abnormal
condition is confirmed. [The BT power supply line
33D circuit is faulty]
Replace the IC6,L2,R71,C59,
C38,C43,R66,L24,L27.
When an abnormal
condition is confirmed.
[The 32.768kHz clock
circuit is faulty]
Replace the X2,L28,C133,
R134.
When an abnormal
condition is confirmed. [/BT_SHDN line circuit
is faulty]
Replace the R132.
IC13 IC12
UART UART
Level
conversion
IC
Bluetooth
IC
IC11
I2S I2S
Level
conversion
IC
X2
32.768kHz
Clock
Charge the BT headset. Turn on your BT headset
and bring it within one to two meters.
Try again pair with BT headset.
When an abnormal
[The MPU or BT IC is faulty]
condition is confirmed.
Replace the PCB.
When an abnormal
[The MPU or BT IC is faulty]
condition is confirmed.
Replace the PCB.
When an abnormal
[The BT IC is faulty]
condition is confirmed.
Replace the PCB.
When an abnormal
[The MPU IC is faulty]
condition is confirmed.
Replace the PCB.
ANT1
L30
Bluetooth
LC
Antenna
Filter