Kenwood NX-3400 Service Manual page 58

Checking the output signal
from the MPU/DSP
Points to be checked
/CS_F IC405 (4pin)
Points to be checked
SBC MPU/DSP side R13
The LCD displays control
Points to be checked
32M L427 side CN402
Points to be checked
/LCD_RST
R479
Points to be checked
/CS4 CP410 (10pin)
It is unlikely that the BGA parts are broken.
When an error display appears on the LCD
The LCD display "INIT ERROR 1".
1) /RST : MPU/DSP reset signal
2) /BINT : Battery final voltage monitoring
3) /PSW : Power switch signal
4) /FRST : Flash memory reset signal
5) /CS_F : Flash memory chip select signal
6) SBC : Switch +B control
7) LCD_RST : LCD reset signal
8) /CS4 : LCD controller chip select signal
1-58 (No.RA070<Rev.001>)
Pass
Normal voltage
Fail
After power-on, and
1.8V 0V 1.8V,
1.8V fixed later
Pass
Fail
Normal voltage
3.2V
Pass
Fail
Normal voltage
3.2V
Pass
Fail
Normal voltage
1.8V
Pass
Normal voltage
Fail
After power-on, and
1.8V 0V 1.8V,
1.8V fixed later
Pass
If the IC405 (1pin) is 0V or 1.8V,
the MPU/DSP may be broken.
If the IC405 (2pin) is 0V or 1.8V,
the MPU/DSP or Flash Memory may be broken.
Remove the following parts.
C28
IC6
R29
Q4
IC14
R13
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 L427 to check the voltage of the 32M.
If the voltage becomes normal, re-insert the FPC of
Display Unit PCB or replace Display Unit PCB.
Remove R479.
If the MPU/DSP side is less than 3.2V,
the MPU/DSP or Flash Memory or mobile DDR
may be broken.
/CS4 has an abnormal voltage.
Check each of the following items.
Re-insert the FPC of Display Unit PCB.
Replace the Display Unit PCB.
As a result, if the abnormality yet, the MPU/DSP
or Flash Memory or mobile DDR may be broken.
If an error occurs when the mobile DDR
internal RAM reads or writes.
The mobile DDR may be broken.
LOW Reset
LOW Final voltage
LOW ON
LOW Reset
LOW Active
HIGH ON
LOW Reset
LOW Active