Question about Emerson EWL20S5 20 in. EDTV-Ready LCD Television

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TV turn on for few seconds then turn off.

I chek the regulators and the switching transistor and everithing looks ok.
I have the service manual and if i disconect the Inverter CBA board i can turn the tv on and it stay on for 10 minutes but no audio. With all conected it turn on and i see the screen with the menu and then off but no sound. Yesterday i was measure the voltage of the IC 602 and 603 with the inverter board disconected and its start to sound for few seconds then off.

I will keep working on it but if you have a suggestion or an answer let me know please.

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Re: TV turn on for few seconds then turn off.

This TV has a network of diodes connected to a PROTECT-1 line monitored by the control IC. If any circuit pulls this line low, the control IC turns the system OFF. The diodes act to isolate all the circuits from each other, its called a diode-OR circuit.
You can troubleshoot by opening a diode which disconnects a circuit from pulling the line low. I had a hunch the EL backlight board was bad, so after opening that protect line the power stayed ON.

I found a bad .068uF 250V cap on the transformer primary, it measured .002uF. I've replaced the cap and the other two on the other transformers just for good measure.

It probably took more time than the TV is worth, but my friend's Mom will be happy, and thats worth it.
I hope this helps, look around for the service manual, it can be found online.

Posted on Jan 15, 2008

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