Trouble Shooting - Kenwood NX-420 K Service Manual

NX-420
Fault Diagnosis of the BGA (Ball Grid Array) IC
■ Overview
A fl owchart 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
ASIC (IC607), DSP (IC601), FLASH (IC600), SRAM (IC603)
When the BGA IC is problematic, please bring the printed circuit board (X57-8370-10) in for service. Various ESN/default ad-
justment values are written on the printed circuit board for service.
Additionally various ESN stickers are included. (Please refer to pages 32.)
After the printed circuit board has been readjusted, please attach any ESN stickers to the chassis. When "ESN Validation" is
used with Trunking, you must modify the ESN register.
Checking power supply voltage
Checking voltage
Points to be checked
33M IC501 (3 pin)
15M IC502 (4 pin)
33A IC500 (3 pin)
Power supply of each device is connected through the coil or R.
[ASIC]
33M: L612, 15M: L611, 33A: L610
[DSP]
33M: L607, 15M: R625
[FLASH]
33M: L605
[SRAM]
33M: L606
Checking the clock
Checking the clock
Points to be checked
18.432MHz ASIC side R638
DSP side R639
Checking the Reset/Control signal
Checking the control signal input to the ASIC
Points to be checked
RESET IC604 (4 pin)
/BINT Q507 (6 pin)
/PSW Q506 (3 pin)
Checking the control signal output from the ASIC
Points to be checked
/FRST C634
Checking the output signal
from the ASIC
Points to be checked
SBC R541
Points to be checked
/DRST R604
30

TROUBLE SHOOTING

When an abnormal
value is confirmed.
Normal voltage
3.3V
1.5V
3.3V
When a normal
value is confirmed.
When an abnormal
value is confirmed.
Normal voltage (3.3V)
18.432MHz
18.432MHz
When a normal
value is confirmed.
When an abnormal
value is confirmed.
Normal voltage
3.3V
3.3V
3.3V
When a normal
value is confirmed.
When an abnormal
value is confirmed.
Normal voltage
3.3V
When a normal
value is confirmed.
When an abnormal
value is confirmed.
Normal voltage
3.3V
When a normal
value is confirmed.
When an abnormal
value is confirmed.
Normal voltage
3.3V
When a normal
value is confirmed.
Checking for an abnormal point
33M has an abnormal voltage.
[ASIC]
Remove L609 to check the voltage of the 33M.
If the voltage becomes normal, the ASIC is broken.
[DSP]
Remove L607 to check the voltage of the 33M.
If the voltage becomes normal, the DSP is broken.
[FLASH]
Remove L605 to check the voltage of the 33M.
If the voltage becomes normal, the FLASH is broken.
[SRAM]
Remove L606 to check the voltage of the 33M.
If the voltage becomes normal, the SRAM is broken.
15M has an abnormal voltage.
[ASIC]
Remove L611 to check the voltage of the 15M.
If the voltage becomes normal, the ASIC is broken.
[DSP]
Remove R625 to check the voltage of the 15M.
If the voltage becomes normal, the DSP is broken.
33A has an abnormal voltage.
[ASIC]
Remove L610 to check the voltage of the 33A.
If the voltage becomes normal, the ASIC is broken.
If the voltage is not corrected, there is a problem
other than the BGA parts.
The BGA parts are not broken.
If the /FRST is always 0V, the ASIC is broken.
If the /FRST repeats 3.3V and 0V at intervals,
The ASIC, FLASH and SRAM may be broken.
Remove R541, Q501 and R522. If the ASIC side is 0V,
the ASIC/FLASH/SRAM may be broken.
If the /DRST is 0V, the ASIC/FLASH/SRAM are broken.