Kenwood NX-5800 Service Manual page 112

Check the Main unit P CB.
Verify the BT/GPS control
signal (TXD2).
CN735 (15 pin): Square waveform
UART data of 3.3V logic.
Baud rate
Default: 115.2kbps
After: 3.967Mbps.
When a normal
condition is confirmed.
Verify the BT/GPS control
signal(RXD2).
CN735 (14 pin): Square waveform
UART tada of 3.3V logic.
Baud rate:
Default: 115.2kbps
After: 3.967Mbps.
When a normal
condition is confirmed.
[The MPU/DSP IC is abnormal]
Replace the PCB.
Descriptions of signal names
(1) 33BT: BT/GPS IC 3.3V power supply
(2) 18BT: BT/GPS IC 1.8V power supply
(3) 33GPS: BT/GPS IC 3.3V power supply
(4) TXD2: BT/GPS serial data line connected to UART TX of MPU/DSP IC (MPU/DSP to BT/GPS IC)
(5) RXD2:BT/GPS serial data line connected to UART RX of MPU/DSP IC (MPU/DSP to BT/GPS IC)
(6) 18BT_HCI_RX: BT/GPS serial data line connected to UART RX of BT/GPS IC (MPU to BT/GPS IC)
(7) 18BT_HCI_TX: BT/GPS serial data line connected to UART TX of GPS IC (BT/GPS IC to MPU)
(8) /BT_SHUTDOWN: BT/GPS active control of MPU/DSP IC (MPU/DSP to BT/GPS IC) High → Active, Low → Reset
1-112 (No.RA017<Rev.003>)
Verify the BT/GPS control
When an abnormal
signal (G_TXD2).
condition is confirmed.
CP705 (2 pin):
Square waveform UART data
of 3.3V logic.
[The TXD2 (18BT_HCI_RX)
line circuit is faulty]
Replace the CP705.
When an abnormal
Verify the BT/GPS control
condition is confirmed.
signal (G_RXD2).
CP705, (3 pin):
Square waveform UART data
of 1.8V logic.
[The RXD2 (18BT_HCI_TX)
line circuit is faulty]
Replace the CP705.
When an abnormal
condition is confirmed.
When a normal
condition is confirmed.
When an abnormal
condition is confirmed.
When a normal
condition is confirmed.
[The MPU/DSP IC is abnormal]
Replace the PCB.
[The MPU/DSP IC is abnormal]
Replace the PCB.