PA70G audio hum - AVS Forum
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post #1 of 5 Old 07-28-2013, 01:16 PM - Thread Starter
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I'm having a problem with a very annoying audio hum when using the PA70G projector. My Blu-ray is connected to projector via HDMI and when I connect the audio to my receiver using the PA70G headphone jack, I get an annoying hum through the speakers while playing the movie. The hum volume adjusts depending on receiver volume control. When I bypass the projector for the audio & instead connect directly to my receiver using digital coax from the Blu-ray, I still get the same hum as long as the video is projecting. If I turn off the projector and listen to the audio only, the hum disappears. I've switched 3 different HDMI cables to see if that was the problem, but did not notice any change...Clearly I seem to be picking up this hum from the projector as part of the video. Incidentally, I have experimented with adjusting the volume control on the projector from high to low & it doesn't seem to have any effect on the hum. Has anybody else had this problem or does anyone know how to fix it? I couldn't find any similar problems on this forum, and would greatly appreciate any help/advice/suggestions as this is driving me nuts......not to mention ruining the movie experience. Thanks
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post #2 of 5 Old 07-28-2013, 05:36 PM
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what audio are you connecting to your receiver? if you have the projector connected to the receiver by hdmi then the audio will run through the hdmi along with the video. I don't get why you would use a headphone jack or digital coax for your audio when the hdmi will do both at once. having two audio connections to the receiver/projector is probably causing the hum/noise. just use the hdmi and the hum should go away.
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post #3 of 5 Old 07-29-2013, 06:02 AM - Thread Starter
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The PA70G projector has an HDMI input, but no HDMI output. The audio output is only from headphone. So, I either run my audio from the headphone jack to the receiver, or I run it from the audio out of the Blu-ray direct to the receiver. In either case I get the hum if the projector is on. Only if I shut the projector off & listen to audio only from the Blu-ray can I eliminate the hum.
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post #4 of 5 Old 07-29-2013, 06:56 AM
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Really you need to extend your troubleshooting to figure out where the problem is.

Try hooking up PC to pa70g and see if you get the hum while watching movies to check out the audio out port on pa70g.
Try hooking up 360 or ps3 to pa70g and see if you get hum.
Unplug the audio speakers from audio out port on pa70g, do you hear hum.
With your blue ray player, if you listen to sound through the internal speakers of pa70g do you get hum if you turn the volume all the way up.
Check if you have any audio options on the blue ray player, maybe there is something you can adjust.
Replace the audio speakers you are using with pc speakers in your house or plug in headphones ijnto the pa70g and see if you get hum.
You see, I just gave you lots of things to trouble shoot, I do it all the time on stuff. It will narrow down for you where the problem is coming from, it could be blu ray player, the cables, the speakers, etc.
Let us know what the problem was when you find it, most times it's something simple, or bad cable that is not insulated right or one of the settings is not adjusted right.
Have fun with your pa70g, and you can always post these type questions in the pa70g thread, and more guys that own the pa70g can help you.
good luck
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post #5 of 5 Old 07-29-2013, 02:45 PM - Thread Starter
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Thanks for your suggestions. Now let me clarify what I have done to try to isolate the problem & why it seems to be an issue with the PA70G projector.

I have connected both the Blu-ray and the DTV receiver to the PA70G with HDMI cables and used the headphone out jack for audio to my receiver. In both cases I get the hum when watching the video from Blu-ray or from DTV. Then I unplugged the headphone jack and used the digital coax output from Blu-ray & the DTV and connected to my receiver. Again, I hear the hum when watching the video from both. Then I put the Blu-ray player on pause and just listen to the hum. Then I do the same for the DTV with the same result. When I cycle the projector off, the hum disappears & I of course hear nothing. Then I hit the play button on each source and while watching & listening to the movie or TV signal (and the hum) I cycle the projector off & listen just to the audio & NO HUM. When I turn the projector back on, the hum returns along with the video picture. It doesn't matter which speaker I play the audio through, it doesn't matter which AV source I use, doesn't matter if I use the headphone audio out jack from the projector or go directly from my source to the receiver, & it doesn't matter what HDMI cable I use or what digital coax cable I use....the only thing that matters is if I turn on the projector to see the video, the hum comes through my speakers. If I listen just to the PA70G speakers, I don't notice the hum no matter what volume...although the tinny sound might mask it, and nobody wants to listen to those speakers anyway even if they don't hum. The problem seems to be isolated to the projector, but why?? Is there some kind of feedback it puts out? I'm at a loss. Thanks for any help
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