Troubleshooting - Kenwood KRK-18H Service Manual

5.1 KRK-18H 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. Connect to the Control Head and RF Deck of the NX-3720/3820 using the KRK-18H, KCT-71
and KRK-19B.
Confirm whether there is a defect in the KRK-18H.
Note:
The firmware of the NX-3720/3820 RF Deck and KRK-18H must be the same version.
BGA parts
MPU (IC16), mobile DDR (IC23), Flash memory (IC29)
Checking the SB (Battery) voltage
Points to be checked
SB TL3
NOTE:
Depends on the battery performance, it may be
less than the voltage value that has been
described above.
Checking the power supply voltage
Points to be checked
12D R46
18D R47
33D R45
18D_Flash R60
53DC L60
NOTE:
Remove the top cover of the BLS to confirm.
And cut the cross bridge part.
Checking the Clock
Points to be checked
R62 (MPU side)
Checking MPU reset signal output from the MPU
Points to be checked
/PRST
D10 (Anode side)
SECTION 5

TROUBLESHOOTING

Standard voltage
K type 13.6V 15%
E type 10.8V~15.6V
Pass
Standard voltage
1.2V
1.8V
3.3V
1.8V
5.3V
Pass
Standard state
amplitude / frequency
1.2Vp-p / 19.2MHz
Pass
Standard voltage
1.8V
Pass
The BGA parts are not broken.
Fail
If the SB is unstable, check the connection and the SB
output from the Mobile Transceiver and the KRK-19B.
"12D" is not Standard voltage.
[MPU]
Remove L12~L16 to check the voltage of the 12D.
If the voltage becomes normal, the removed parts or the
subsequent parts are broken.
NOTE:
IC30 (12D DC/DC Converter Device) is fragile in the
scratch. Be careful when you touch this part.
"18D" is not Standard voltage.
[MPU]
Remove L17 and L18 to check the voltage of the 18D.
If the voltage becomes normal, the removed parts or the
subsequent parts are broken.
Fail
[mobile DDR]
Remove L30 to check the voltage of the 18D.
If the voltage becomes normal, the removed part or the
subsequent parts are broken.
[LCD]
Remove L61 to check the voltage of the 18D.
If the voltage becomes normal, the removed part or the
subsequent parts are broken. (Including FFC)
"33D" is not Standard voltage.
[MPU]
Remove L19 to check the voltage of the 33D.
If the voltage becomes normal, the removed part or the
subsequent parts are broken.
[Flash Memory]
Remove L36 to check the voltage of the 33D.
If the voltage becomes normal, the removed part or the
subsequent parts are broken.
[LCD]
Remove L59 to check the voltage of the 18D.
If the voltage becomes normal, the removed part or the
subsequent parts are broken. (Including FFC)
"18D_Flash" is not Standard voltage.
[Flash Memory]
Remove L35 to check the voltage of the 18D_Flash.
If the voltage becomes normal, the removed part or the
subsequent parts are broken.
"53DC" is not Standard voltage.
[LCD]
Remove L60 to check the voltage of the 53DC.
Fail
If the voltage becomes normal, the removed part or the
subsequent parts are broken. (Including FFC)
Amplitude or Frequency is abnormal.
Remove R62 to check the amplitude and frequency of X1.
If the amplitude and frequency becomes normal, the MPU
or removed part are broken.
"/PRST" is not Standard voltage.
Fail
If voltage of TL9 is over 1.8V, check D10, R69 and C10.
If those parts are normal, the MPU is broken.
(No.RA062<Rev.001>)1-13