Vizio e420vse audio problem

[freakaftr8]

So I received this TV from a customer who stated they were watching it when the audio went to a really high pitch squealing noise and turning the volume completely down or up had no bearing or effect on the sound. They turned off the TV and turn it back on and it went back to normal. I received the TV to check it out and audio was working fine for the first day of running it, now there is no audio at all either through HDMI or composite input. This uses a tas5717 audio processor/amp. I have not checked voltage is going to the audio processor as of yet. This board is known for failing eprom however all menus work perfect and so does the picture. I'm under the impression that the audio amp has failed however I would like to see if anyone else has encountered this problem before with this model. Main board model is 55.73x01.b01

Also I should know if it already tried some fire and ice around the board with no results

Thanks

[dick_barton]

Re: Vizio e420vse audio problem

Can you do a factory reset.

https://www.badcaps.net/forum/showth...ighlight=class

[dskall]

Re: Vizio e420vse audio problem

Maybe bad cap feeding the audio power

[freakaftr8]

Re: Vizio e420vse audio problem

Possibly. I'll investigate further. Haven't tried either as of yet.

[freakaftr8]

Re: Vizio e420vse audio problem

Ok. Audio receives power. Factory reset yielded no results. Checked ohms on speakers. Confident it's the audio processor.

[dick_barton]

Re: Vizio e420vse audio problem

The audio receives its commands (up/down etc) via the I2C link. Could it be an EEPROM / Firmware issue?

[freakaftr8]

Re: Vizio e420vse audio problem

Not too sure but I show on the two I2C inputs, 3.3v. So obviously it's getting some data and clock information. Also the analog input show voltage as well. However should I be scoping these analog pins instead of testing voltage for frequency changes corresponding to the audio input to the IC?

[dick_barton]

Re: Vizio e420vse audio problem

The best way is, as you suggest, to scope the lines.

There are two supplies to the chip. 3.3V for DVDD, AVDD & HPVDD. Also PVDD_X has a maximum voltage of 30V according to the data sheet.

The TAS5717/9 has an over temperature protection system

[freakaftr8]

Re: Vizio e420vse audio problem

Thanks Dick for that. At my daughter's birthday party going on today but as soon as I'm done I'll check into these voltages and let you know what I find out