Troubleshooting - Kenwood KRK-14H Service Manual

5.1 KRK-14H 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. As necessary, connect the NX-5700/5800 and KCH-19 directly. Confirm whether there is a
defect in the KRK-14H and KRK-15B.
BGA parts
MPU (IC16), mobile DDR (IC23), Flash memory (IC29)
Checking SB (Battery) voltage
Points to be checked
SB CN3
NOTE:
Because it depends on the battery performance, it may be
less than the voltage value that has been described above.
Checking power supply voltage
Checking voltage
Points to be checked
12D R46
18D R47
33D R45
18D_Flash R60
Power supply of each device is connected through the coil.
[MPU]
12D: L12, L13, L14, L15, L16
18D: L17, L18
33D: L19
[mobile DDR]
18D: L30
[Flash Memory]
33D: L36
18D_Flash: L35
Checking the clock
Checking the clock
Points to be checked
19.2MHz
MPU side R62
Checking the Reset/Control signal
Checking the control signal input to the MPU
Points to be checked
/PRST D10 (Anode side)
1-12 (No.RA021<Rev.001>)
SECTION 5

TROUBLESHOOTING

When an abnormal
Normal voltage
value is confirmed.
13.6V 15%
When a normal
value is confirmed.
When an abnormal
value is confirmed.
Normal voltage
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
When a normal
value is confirmed.
The BGA parts are not broken.
If the CN3 is 0V or unstable, check the SB
output of NX-5700/5800 Main unit.
Checking for an abnormal point
12D has an abnormal voltage.
[MPU]
Remove L12~L16 to check the voltage of the 12D.
If the voltage becomes normal, the MPU is broken.
NOTE:
A1(12D DC/DC Converter Device) is fregile
in the scratch.
Be careful when you touch this parts.
18D has an abnormal voltage.
[MPU]
Remove L17 and L18 to check the voltage
of the 18D.
If the voltage becomes normal, the MPU is broken.
[mobile DDR]
Remove L30 to check the voltage of the 18D.
If the voltage becomes normal, the mobile
DDR is broken.
33D has an abnormal voltage.
[MPU]
Remove L19 to check the voltage of the 33D.
If the voltage becomes normal, the MPU is broken.
[Flash memory]
Remove L36 to check the voltage of the 33D.
If the voltage becomes normal, Flash memory
is broken.
18D_Flash has an abnormal voltage.
[Flash memory]
Remove L35 to check the voltage of the 18D_Flash.
If the voltage becomes normal, Flash memory
is broken.
The BGA parts are not broken.