Hi all,
I'm pretty much done with the diagnosis of this LG 60PK550 plasma TV. But I want a second opinion.
The problem is that on startup the VA voltage is stable at 60 volts as it should be, then after 10 seconds it raises rapidly to 70 volts where the power supply shuts down to protect everything.
By disconnecting various boards, I've isolated the problem to the lower left XL buffer board. When I disconnect the power cable (carrying GND and VA) between the Y sustaining board and the XL buffer board, VA on the power supply side stays rock steady at 60 volts. But on the XL buffer board side VA climbs instantly to >100 volts. Doing the same on the XC and XR buffer boards, VA climbs by itself to something that never go beyond 25 volts.
Lucky as I am, I have second TV of the exact same model. Swapping all the boards from the good one to the bad one changed nothing at all.
It's clear for me that something is back feeding some higher voltage into VA through one of the XL buffer board's panel connectors. I've disconnected all eight of them, one by one, trying to isolate a shorted vertical line, or a bad flex cable glued ship, but nothing stopped the voltage leak to the XL board VA voltage.
What's your opinion on this one?
I'm pretty much done with the diagnosis of this LG 60PK550 plasma TV. But I want a second opinion.
The problem is that on startup the VA voltage is stable at 60 volts as it should be, then after 10 seconds it raises rapidly to 70 volts where the power supply shuts down to protect everything.
By disconnecting various boards, I've isolated the problem to the lower left XL buffer board. When I disconnect the power cable (carrying GND and VA) between the Y sustaining board and the XL buffer board, VA on the power supply side stays rock steady at 60 volts. But on the XL buffer board side VA climbs instantly to >100 volts. Doing the same on the XC and XR buffer boards, VA climbs by itself to something that never go beyond 25 volts.
Lucky as I am, I have second TV of the exact same model. Swapping all the boards from the good one to the bad one changed nothing at all.
It's clear for me that something is back feeding some higher voltage into VA through one of the XL buffer board's panel connectors. I've disconnected all eight of them, one by one, trying to isolate a shorted vertical line, or a bad flex cable glued ship, but nothing stopped the voltage leak to the XL board VA voltage.
What's your opinion on this one?
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