LG 60PB66550 NOV 2014
PSU: EAY63168603
PCB: EAX65359531 2013.11.01 Rev:1.0
Main board: EAX65399305(1.0) 13.11.27 PU42A/PA42A/PD42A
Symptom:
While watching, just went black and started clicking relay every few seconds.
Initial diagnosis:
Removing JUST the main CPU/Input PCB from circuit stops the clicking. No problems with any other boards/drivers. (Removing all other boards and only putting Main back in is all it takes to start clicking again)
Deeper diagnosis:
Pulling pins #1/#2 (Blue/Grey) from the connector housing at the power board connector P813 (17V pins), allows main board to be reconnected either alone or with all other boards, and then does not click. Screen even lights with very dim green pixels as it had normally with otherwise black screen.
I pulled all electrolytics from power board and test fine with cap tester with low ESR. No bulging of those or any of the blue rectangular caps (which have not been pulled or tested yet).
There is about 10.2 ohm resistance between the 17V line and GND on the mainboard testing it when pulled from set. There is exactly 16.88 V (no load) at the pin on the power supply when it is disconnected from the mainboard.
Questions:
Is the issue a short in the main logic board or a problem with a weak 17V rail on the power supply? I spot checked transistors on power board in circuit with diode check on DMM and didn't find any obviously shorted. What use is the 17V feed as compared with the normal 5.2V rails?
Would a new main logic board fix the problem or is it something else?
Thanks much in advance!
PSU: EAY63168603
PCB: EAX65359531 2013.11.01 Rev:1.0
Main board: EAX65399305(1.0) 13.11.27 PU42A/PA42A/PD42A
Symptom:
While watching, just went black and started clicking relay every few seconds.
Initial diagnosis:
Removing JUST the main CPU/Input PCB from circuit stops the clicking. No problems with any other boards/drivers. (Removing all other boards and only putting Main back in is all it takes to start clicking again)
Deeper diagnosis:
Pulling pins #1/#2 (Blue/Grey) from the connector housing at the power board connector P813 (17V pins), allows main board to be reconnected either alone or with all other boards, and then does not click. Screen even lights with very dim green pixels as it had normally with otherwise black screen.
I pulled all electrolytics from power board and test fine with cap tester with low ESR. No bulging of those or any of the blue rectangular caps (which have not been pulled or tested yet).
There is about 10.2 ohm resistance between the 17V line and GND on the mainboard testing it when pulled from set. There is exactly 16.88 V (no load) at the pin on the power supply when it is disconnected from the mainboard.
Questions:
Is the issue a short in the main logic board or a problem with a weak 17V rail on the power supply? I spot checked transistors on power board in circuit with diode check on DMM and didn't find any obviously shorted. What use is the 17V feed as compared with the normal 5.2V rails?
Would a new main logic board fix the problem or is it something else?
Thanks much in advance!
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