Vizio E421Va sound going up and down by itself

[brucetv]

I've got a Vizio E421VA Tv in the shop and the customer says the volume goes up and down by itself. He uses Cox cable and I can't get it to repeat the problem. Has anybody seen this problem before? Bad Ir Sensor maybe or bad key controller? All the functions on the remote work fine and respond to all menu options fine. Thx

[Agent24]

Re: Vizio E421Va sound going up and down by itself

If bad IR or Keypad I would expect it to either jam with volume going up OR down, not both.

You should see the volume OSD if it's a problem with either input anyway, did he confirm this? Did he say it happens with everything or just cable?
If the sound changes but no OSD shows up it's more likely a signal source or amplifier problem. Maybe the problem is his cable receiver.

First thing that springs to mind is there may be some slow oscillation in whatever circuit controls the gain in some part of the audio stage, somewhere in TV or cable box. Sounds strange though.

May have to check it out on-site...