I don't want to hijack rowage's thread so I start my own.
A friend gave me a PS50Q97HD that quit working with a "bang and smoke".
Opened it up and directly saw a blown Y-buffer chip.
Measured the FET's on the Y-main and one was shorted and i replaced it.
One cap was also bad and is now also replaced. (se attached picture)
I desoldered the bad Y-buffer chip and tested the tv with just the lower Y-buffer in place. (didn't know that the image bus was delivered through the upper board at that point)
The panel lighted up and I saw that the lower half was glowing.
I then tested with both the upper and lower buffer in place and only upper. (got picture on 3/4 of the top part with just the upper board in place for some second) but then something happened. (whole screen went dark)
All (or at least 7 of the 8) buffers got shorted and one more FET on the Y-main shorted again.
I just replaced all the FET's on the lower left heatsink and powered it up again without any Y-buffer boards installed. It hear a buzzing sound from the Y-main and the green LED is active on the Y-main.
The upper buffer board connector has the same voltages as the lower buffer connector.
The 60v i measure is going down the longer the TV is on. (and the buzzing gets louder and louder, I don't have the tv on for more than ~30sec)
No negative voltages are present at the connectors.
VS-voltage is 206v (as it should be) and all the other voltages is correct from the power supply board.
The white front power LED on the tv set blinks 6 times when power is applied.
All help is appreciated.
A friend gave me a PS50Q97HD that quit working with a "bang and smoke".
Opened it up and directly saw a blown Y-buffer chip.
Measured the FET's on the Y-main and one was shorted and i replaced it.
One cap was also bad and is now also replaced. (se attached picture)
I desoldered the bad Y-buffer chip and tested the tv with just the lower Y-buffer in place. (didn't know that the image bus was delivered through the upper board at that point)
The panel lighted up and I saw that the lower half was glowing.
I then tested with both the upper and lower buffer in place and only upper. (got picture on 3/4 of the top part with just the upper board in place for some second) but then something happened. (whole screen went dark)
All (or at least 7 of the 8) buffers got shorted and one more FET on the Y-main shorted again.
I just replaced all the FET's on the lower left heatsink and powered it up again without any Y-buffer boards installed. It hear a buzzing sound from the Y-main and the green LED is active on the Y-main.
The upper buffer board connector has the same voltages as the lower buffer connector.
The 60v i measure is going down the longer the TV is on. (and the buzzing gets louder and louder, I don't have the tv on for more than ~30sec)
No negative voltages are present at the connectors.
VS-voltage is 206v (as it should be) and all the other voltages is correct from the power supply board.
The white front power LED on the tv set blinks 6 times when power is applied.
All help is appreciated.
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