Panasonic TX-p42G20B causes amplifier interference – grounding problem?


Active Member
Setup - Panasonic TX-p42g20b connected via phono leads to an AV amp (centre and surround left/right). AV amp pre outs connected to power amp video inputs of a 2 channel integrated amp (front left and right).

In the configuration above as soon as I switch on the Panny 42g20 I get terrible interference through my speakers. The interference changes with the picture displayed by the 42G20b, which matches the physical buzzing noise the set makes, especially with the guide button – a black blank screen seems especially bad.

If I switch off the TV the interference disappears, and changing the AV amp input to tuner is fine. No matter what input is selected on the AV amp and the 2 channel integrated amp is on video input, as soon as the TV is switched on the interference occurs.

If I run just the Panasonic TX-p42g20b connected via phono leads to the AV amp (all 5 speakers) I get no interference.

I’ve disconnected all electrical connections between the TV and the AV amp and tried an optical cable, but still the buzzing remains. If I change the integrated amp to another input with the TV on the buzzing disappears.

I’ve tried a grounding cable from the moving magnet stage of the integrated amp to the TV chassis/phono cable exterior conductor with no effect.

I’ve had the same problem with a different AV amp/2 channel amp configuration, so this suggests the Panny TV is faulty? I’ve already eliminated mains hum by connecting the TV and integrated amp via different 4 way gang extensions, so could I have a grounding problem?

Has anyone else had similar problems?

Thanks in advance!

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