Troubleshooting - Kenwood TH-D74E Service Manual

5.1 Fault Diagnosis of the BGA (Ball Grid Array) IC
Overview
A flowchart for determining whether or not the transceiver can be powered on (the LCD does not function even if the power switch is
turned on) due to broken BGA parts.
BGA parts
MAIN MPU(IC702), mobile DDR(IC701), Flash Memory(IC705)
Checking Battery voltage
Points to be checked
+B TL587
Checking power supply voltage
Checking voltage
Points to be checked
12M C828
18M C827
33M IC712 1pin
18M_3 IC724 1pin
Power supply of each device is connected
through the coil.
[MAIN MPU]
12M L705 L706 L707
18M L703 L704
[mobile DDR]
18M L700
[Flash Memory]
18M_3 L702
Checking the clock
Checking the clock
Points to be checked
19.2MHz
MAIN MPU side R722
Checking the Reset/Control signal
Checking the control signal input to the MAIN MPU
Points to be checked
/RST IC703 4pin
/BINT Q701 6pin
1-44 (No.RA044<Rev.001>)
SECTION 5

TROUBLESHOOTING

When an abnormal
value is confirmed.
Normal voltage
6 9V
When a normal
value is confirmed.
When an abnormal
Normal voltage
value is confirmed.
1.2V
1.8V
3.3V
1.8V
When a normal
value is confirmed.
When an abnormal
value is confirmed
Normal voltage (1.2V)
19.2MHz
When a normal
value is confirmed.
When an abnormal
value is confirmed.
Normal voltage
1.8V
3.3V
When a normal
value is confirmed.
The BGA parts are not broken.
If the TL587 is less than 6V,
charge the battery.
Checking for an abnormal point
12M has an abnormal voltage.
[MAIN MPU]
Remove L705 and L706 and L707 to check the
voltage of the 12M.
If the voltage becomes normal, the MAIN MPU is
broken.
18M has an abnormal voltage.
[MAIN MPU]
Remove L703 and L704 to check the voltage of
the 18M.
If the voltage becomes normal, the MAIN MPU is
broken.
[mobile DDR]
Remove L700 to check the voltage of the 18M.
If the voltage becomes normal, the mobile DDR is
broken.
18M_3 has an abnormal voltage.
[Flash Memory]
Remove L702 to check the voltage of the 18M_3.
If the voltage becomes normal, Flash Memory is
broken.
If the voltage is not corrected, there is a
problem other than the BGA parts.
The BGA parts are not broken.