Kenwood TH-D74E Service Manual page 45

Checking the control signal output from the MAIN
MPU
Points to be checked
/FRST
Flash Memory side D700
The LCD displays control
Points to be checked
30M IC713 1pin
Points to be checked
/RESET LCD_RST
CN702 11pin
Points to be checked
/CS4 CN702 10pin
It is unlikely that the BGA parts are broken.
When an error display appears on the LCD.
The LCD displays "INIT ERROR 1".
Descriptions of signal names
(1) /RST
(2) /BINT
(3) /FRST
(4) /CS_F
(5) 30M
(6) /RESET(LCD_RST)
(7) /CS4
When a normal
value is confirmed.
Normal voltage
1.8V
When a normal
value is confirmed.
Normal voltage
3.0V
When a normal
value is confirmed.
Normal voltage
1.8V
When a normal
value is confirmed.
Normal voltage
After power-on,
and
1.8V 0V 1.8V,
1.8V fixed later
When a normal
value is confirmed.
:MAIN MPU reset signal
:Battery final voltage monitoring
:Flash Memory reset signal
:Flash Memory chip select signal
:LCD module control 3.0V power supply
:LCD reset signal
:LCD controller chip select signal
If the /FRST is always 0V, the MAIN MPU is
When an abnormal broken.
value is confirmed.
Remove D700 to check the voltage of Flash
Memory side R762.
If the voltage becomes abnormal, Flash Memory
is broken.
When an abnormal
value is confirmed. The BGA parts are not broken.
Remove R802 to check the voltage of the 30M.
If the voltage becomes normal, re-insert the FPC of
LCD module or replace the LCD module.
Remove Q703.
When an abnormal
If the MAIN MPU side is 3.3V,
value is confirmed.
the MAIN MPU or Flash Memory or mobile DDR
may be broken.
/CS4 has an abnormal voltage.
Check each of the following items.
Check to see the terminal of FL700.
When an abnormal
Re-insert the FPC of LCD module.
value is confirmed.
Replace the LCD module.
As a result, if the abnormality yet,
the MAIN MPU 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.
LOW → Reset
LOW → Final voltage
LOW → Reset
LOW → Active
LOW → Reset
LOW → Active
(No.RA044<Rev.001>)1-45