LG 42PC3RA Service Manual page 26

4. Protect Mode
(1) Symptom
1) After once shining, it does not discharge minutely
from module.
2) The Rely falls down.(The sound is audible "click")
3) The front LED turn Green to Red.
(2) Check following
Is normal PSU?
Yes
Is normal cables?
Yes
Is normal Y-board?
Yes
Is normal Z-board?
Yes
Is normal X-board?
Yes
Is normal Ctrl B/D?
Yes
Is normal Main B/D?
Yes
Are COFs normal?
No
Does the Low/High voltage
operate normally?
No
Do cable connect well each
wafer?
No
Are Fuses(FS2, FS3) normal?
(Exchange the fuse at abnormal)
No
Are Fuses(FS1, FS2) Normal?
(Exchange the fuse at abnormal)
No
Disconnecting cable( P1,3,4,105)
at X-board, are Va/Vs normal?
No
Disconnecting cable(P4, 5, 6, 7, 10, 11)
at Ctrl board, are Va/Vs normal?
No
Disconnecting cable(P301, P900, P1001)
at main B/D, are Voltages normal?
No
After crisis COF of each board, check the normality operates. If in case normality
operates, correspondence COF Fail is replace the module.
No
Exchange the
PSU
No
Exchange the
cable
Disconnecting
Yes
cable(P1, P152)
at Y-board, are
Va/Vs normal?
Disconnecting
Yes
cable(P1, P2, P6)
at Z-board, are
Va/Vs normal?
Yes
Disconnecting P1/P3, Va/Vs is normal :
Exchange Right X-B/D
Disconnecting P4/P105, Va/Vs is normal :
Exchange Left X-B/D
Yes
Exchange Ctrl board
Yes
Exchange Main board
Yes
Exchange Y-
board
Yes
Exchange Z-
board