Troubleshooting - Kenwood NX-3720HG 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
MPU/DSP(IC404), mobile DDR(IC402), Flash Memory(IC401)
When the BGA IC is problematic, please bring the printed circuit board (XCA-033K-00/XCA-033E-01/XCA-034K-00/XCA-034K-01/
XCA-034E-01) in for service. Various ESN/ default adjustment values are written on the printed cicuit board for service.
Additionally various ESN stickers are included. (Please refer to "5.4 Replacing TX-RX Unit".)
After the printed circuit board has been readjusted, please attach any ESN stickers to the chassis. When "ESN Validation" is used,you
must modify the ESN register.
Checking power supply voltage
Checking voltage
Points to be checked
12M C40
18M C57
32M IC20(5pin)
18M_3 IC21(1pin)
Power supply of each device is connected through the coil.
[MPU/DSP]
12M: L405, L406, L408
18M: L410, L411
32M: L412
[mobile DDR]
18M: L403
[Flash Memory]
32M: L401
18M_3: L413
Checking the clock
Checking the clock
Points to be checked
19.2MHz
MPU/DSP side R424
Checking the Reset/Control signal
Checking the control signal input to the MPU/DSP
Points to be checked
/RST D14(Anode side)
/BINT2 CN17
/OVRB_OUT IC22(12pin)
Checking the MPU/DSP input switch signal
The POWER key is pressed and held.
Points to be checked
/PSW_OUT IC22(15pin)
The ignition key is kept ON.
Points to be checked
/IGN_OUT IC22(9pin)
1-152 (No.RA054<Rev.001>)
SECTION 5

TROUBLESHOOTING

Fail
Normal voltage
1.2V
1.8V
3.2V
1.8V
Pass
Normal voltage (1.2V)
Fail
19.2MHz
Pass
Fail
Normal voltage
1.8V
3.1V
3.1V
Pass
Confirmed voltage
ON: 0V
OFF: 0V 3.1V
Fail
Confirmed voltage
ON: 0V
OFF: 0V 3.1V
Pass
Checking for an abnormal point
12M has an abnormal voltage.
[MPU/DSP]
Remove L405 and L406 and L408 to check the
voltage of the 12M.
If the voltage becomes normal, the MPU/DSP is
broken.
Note: IC24(12M DC/DC Converter Device) is
fragile in the scratch.
Be careful when you touch this parts.
18M has an abnormal voltage.
[MPU/DSP]
Remove L410 and L411 to check the voltage
of the 18M.
If the voltage becomes normal, the MPU/DSP
is broken.
[mobile DDR]
Remove L403 to check the voltage of the 18M.
If the voltage becomes normal, the mobile DDR
is broken.
32M has an abnormal voltage.
[MPU/DSP]
Remove L412 to check the voltage of the 32M.
If the voltage becomes normal, the MPU/DSP
is broken.
[Flash Memory]
Remove L401 to check the voltage of the 32M.
If the voltage becomes normal, Flash memory
is broken.
18M_3 has an abnormal voltage.
[Flash memory]
Remove L413 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.*1
The BGA parts are not broken.
The BGA parts are not broken.
Check the peripheral circuit of IC2.*2