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How can I diagnose the power board in OLED55CXPUA?

Lots of searching has led me to suspect the power board.

I have the back off, and the part number is EAY65689401... I have my Fluke in hand but I can't find any info on what to measure.

Update (02/18/24)

Thank you jayeff -- I appreciate your response.

The layout of the board is noticeably different than what I have. Is it reasonable to presume that it is another power board that works in a TV model with the same main board and the P201 signals are the same?

BTW -- my situation is that a month (or bit more) ago, the tv would hang up after a while, and once it did it would repeat more quickly until I turned it off and walked away. Lots of variations: simply reboot (a reboot usually happens; but often after a freeze of the screen or a static image or vertical lines); screen goes blank but audio continues for a while; very loud noise -- causing me to jump up and pull the plug; static noise. There is never any response to the remote. This has all gotten worse (fails sooner) over the ensuing weeks.

The screen as absolutely fine and I do not have urgency; which leads me to consider just replacing boards (power then main??) since that is fairly easy and replacements are inexpensive relative to the TV overall, or to an at-home service call. But, any diagnosing I can do seems worthwhile.

All feedback (well -- ifixit-worthy ;-) appreciated.

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Hi @bporter38429

Here's an image of where to test the power board voltages for the power board model you posted.

Block Image

(click on image)

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Hi @bporter38429,

Interesting.

The image of the board came from the service manual for a different TV model which purportedly uses a power board having the same board model number as posted by you. I couldn't find a service manual for your model so I thought that service manuals for other TV models using the same power board might be the way to go.

To me it seems more of a mainboard problem rather than a power board problem.

The power board only supplies power to the other components in the TV under the direction of the mainboard.

All the symptoms that you describe comes under the control of the mainboard.

Perhaps the next time it fails so to speak, perform a power refresh and then check if it starts again OK when you restart it.

Turn off the TV and then disconnect the power cord from the TV. Next press and hold the TV's power on button for a full 30 seconds and then release it.

Reconnect the power and first check that the TV's standby power light turns on and if so try starting the TV using the remote.

If it works OK I think that the mainboard may be the culprit as the software that controls the TV operation is located on that board.

If you decide to replace the mainboard first, search for suppliers that have a good returns policy with perhaps only a small restocking fee, so as to minimize the cost to you in case it isn't the problem.

Perhaps if it is working OK for long enough check what firmware version is installed in the TV.

You didn't give the full model number but searching online it appears that the latest firmware Version 04.50.53 is applicable to all models in the series and was issued on Jan 4 2024. Always worth checking that the firmware is up to date just in case.

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IMPORTANT

Double check that any firmware update is applicable to your exact model i.e. full model number, not just model series, as installing the incorrect firmware can brick a TV. Search online for "(insert full model number) firmware" or "(insert full model number) support" to find information for your exact model

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B.Porter will be eternally grateful.
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