Kenwood NX-3720HG Service Manual page 153

Checking the output signal
from the MPU/DSP.
Checking the control signal output from the MPU/DSP
Points to be checked
/FRST
D401(Anode side)
Points to be checked
/CS_F IC403(4pin)
Points to be checked
SBC MPU/DSP side R62
The LCD displays control
Points to be checked
54M C520
18M C519
32M C511
The LCD displays control
Points to be checked
PRST
D410(Cathode side)
Points to be checked
/CS_LCD CP412(8pin)
It is unlikely that the BGA parts are broken.
When an error display appears on the LCD
The LCD display "INIT ERROR 1".
Descriptions of signal names
1) /RST : MPU/DSP reset signal
2) /BINT : Battery final voltage monitoring
3) /OVRB_OUT : Battery overvoltage monitoring
4) /PSW_OUT : Power switch signal
5) /IGN_OUT : Ignition switch signal
6) /FRST : Flash Memory reset signal
7) /CS_F : Flash Memory chip select signal
8) SBC : Switch +B control
9) PRST : LCD reset signal
10) /CS_LCD : LCD controller chip select signal
Pass
Normal voltage
Fail
1.8V
Pass
Fail
Normal voltage
After power-on,
and
1.8V 0V 1.8V,
1.8V fixed later
Pass
Fail
Normal voltage
3.2V
Pass
Fail
Normal voltage
5.36V
1.8V
3.2V
Pass
Normal voltage Fail
3.2V
Pass
Normal voltage
Fail
After power-on,
and
1.8V 0V 1.8V,
1.8V fixed later
Pass
If the /FRST is always 0V, the MPU/DSP is broken.
Remove D401 to check the voltage of Flash memory
side R433.
If the voltage becomes abnormal, Flash memory is
broken.
If the IC403 (1pin) is 0V or 1.8V,
the MPU/DSP may be broken.
If the IC403 (2pin) is 0V or 1.8V,
the MPU/DSP or Flash memory may be broken.
Remove R62 to check the voltage of the SBC.
If the MPU/DSP side is 0V,
the MPU/DSP or Flash memory or mobile DDR
may be broken.
The BGA parts are not broken.
Remove the FFC of TX-RX unit between Sub
(Display) unit.
If the voltage becomes normal, the FFC or Sub
(Display) unit is broken.
Remove Q403.
If the MPU/DSP side is 3.2V, the MPU/DSP or Flash
memory or mobile DDR may be broken.
/CS_LCD has an abnormal voltage.
Check each of the following items.
Check to see the terminal of L419 and CP412.
Remove the FFC of TX-RX unit between
Sub (Display) Unit.
As a result, if the abnormality yet, the MPU/DSP or
Flash memory or mobile DDR may be broken.
An error occurs when the mobile DDR internal
RAM reads or writes.
The mobile DDR may be broken.
Check the flowchart from beginning.
LOW Reset
LOW Final voltage
LOW Overvoltage
LOW ON
LOW ON
HIGH Reset
LOW Active
HIGH ON
HIGH Reset
LOW Active
(No.RA054<Rev.001>)1-153