plasma tv repair

How To Repair No Picture Problem in Plasma TV

plasma tv repair

Picture 1

Pic1: Here is a plasma tv that has audio but no picture. Damon is using a digital scope that is '100 mega-samples p/s' to troubleshoot the display problem.

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Picture 2

Pic2: In conjunction to using the scope Damon also monitors the Vs voltage (196v) using a digital multimeter. This Vs voltage is supplied from the power board to the Y sustain. Y sustain uses the Vs supply to generate the sustain waveform output going to the Y electrodes of the panel.

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Picture 3

Pic3: Now that the Vs supply is confirmed Damon programs the scope and is now connecting the scope probe to the test bead of the Y sustain to measure the high voltage sustain signal. The scope probe is set to X10.

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Picture 4

Pic4: Immediately after connecting the probe the oscilloscope reveals a major upset in the sustain waveform. Damon is pointing to the squiggly traces at the top left peak and bottom left peak of the sustain signal. This is FET damage.

plasma television troubleshooting

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Pic5: Here’s a closer observation of the faulty sustain signal. The sustain period can not complete its charge cycle with bad output FETs. This kind of failure usually causes a 'no-picture' symptom.

plasma tv waveform

Picture 6

Pic6: Here Damon points to the heatsink of the module that is causing the problem on the Y sustain board. The scope has revealed that the module has internal FETs which are defective and require servicing.

plasma tv repairing and troubleshooting