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 Post subject: Weird audio output matching issue
PostPosted: Apr Wed 10, 2019 7:55 pm 
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Joined: Aug Tue 04, 2009 2:15 pm
Posts: 355
Location: Elmira, NY
I’m a a point of frustration, I may be overlooking the obvious, but i’m Stuck.

I have a Hisense flatscreen tv and a Yamaha ,high end, receiver.

I’m connecting the 1/8” 3 wire stereo headphone output jack to the aux input , RCA jacks,of the receiver. There are no other audio outputs to connect to.

Intermittently, the right channel cuts out. To fix: I disconnect the right channel RCA plug and re-insert. live). This fixes the problem for a while. Sometimes it last 10 minutes, sometimes an hour.

I’ve tried 22 ohms and 1k ohms resistor across each line thinking it is a loading issue.
No Resolution.

When I connect a pair of amplified computer speakers to the tv there is no issues. It plays hours on end, no problem.

Obviously, it’s a matching issue with the receiver. ( I think). Any suggestions?


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 Post subject: Re: Weird audio output matching issue
PostPosted: Apr Wed 10, 2019 8:02 pm 
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Joined: Feb Thu 28, 2019 7:48 pm
Posts: 250
Location: Lawrenceville, Illinois 62439
Reverse your left and right plugs on the receiver. If the right channel continues to act up, it's the receiver. May help narrow down the problem.
Dan


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 Post subject: Re: Weird audio output matching issue
PostPosted: Apr Wed 10, 2019 8:20 pm 
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Joined: Aug Tue 04, 2009 2:15 pm
Posts: 355
Location: Elmira, NY
No, it’s definitely only the right Channel from the tv that cuts out. I can move it to the other channel.
Both inputs on the receiver are fine. But... if I use a different amplifier the issue goes away.
If I use headphones attached to tv there’s no issue.

The amplified PC speakers are battery operated. (No issue with these)

I’m thinking. The non isolated. Switching supply of the tv , is fighting the linear supply in the receiver. (Or I’m overthinking/overcomplicating).

I even tried isolating one of the shielding grounds of the RCA pugs. To no avail.

It’s like a capacitor in the tv output is charging up and then cutting out. (Only one channel).When I disconnect/re-connect I get a loud burst of hum and then it starts working. For a while.


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 Post subject: Re: Weird audio output matching issue
PostPosted: Apr Wed 10, 2019 8:22 pm 
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Joined: Aug Tue 04, 2009 2:15 pm
Posts: 355
Location: Elmira, NY
If the channel cut out with any other load: internal speakers, headphones, external amp, I would suspect a definite problem with the tv.

The reciever works fine with all other media inputs as well.


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 Post subject: Re: Weird audio output matching issue
PostPosted: Apr Wed 10, 2019 9:30 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 20366
Location: Utica, NY 13502 (USA)
Is there a DC component on the output of the TV? If so, that may be upsetting that particular amplifier since you said it works OK with a different amplifier.

Dave


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 Post subject: Re: Weird audio output matching issue
PostPosted: Apr Thu 11, 2019 12:35 am 
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Joined: Sep Mon 16, 2013 2:42 am
Posts: 3288
Location: Tucson, Arizona U.S.A.
Did you try a different cable? Perhaps your's is broken.

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Jim Mueller


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 Post subject: Re: Weird audio output matching issue
PostPosted: Apr Thu 11, 2019 2:12 am 
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Joined: Feb Sat 12, 2011 2:29 pm
Posts: 538
Location: Fayette County, Pa
I would be looking for DC on the audio out from the tV. Leaky Coupling cap problem on the line out of the TV? One "fix" might be to use an external cap between the line out and cable. However this might only be temporary as whatever is really the problem may eventually fail completely.


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 Post subject: Re: Weird audio output matching issue
PostPosted: Apr Thu 11, 2019 3:01 am 
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Joined: Jul Fri 18, 2008 10:02 am
Posts: 2104
Location: near ST Louis Mo 62002
If your tv has a digital out or toslink out , this could be used for an audio out . I just bought one to use with headphones for my tv in the bedroom .


https://www.ebay.com/itm/Digital-Coaxia ... 2749.l2649

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 Post subject: Re: Weird audio output matching issue
PostPosted: Apr Thu 11, 2019 4:26 am 
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Joined: Aug Tue 04, 2009 2:15 pm
Posts: 355
Location: Elmira, NY
i put a meter on both output lines of the tv. I saw no dc, just mV signals on both lines.
It cut out again, with no change of output on either line, proving that circuit ok.
I now believe one of the aux inputs is cutting out on the receiver. I was sure I checked receiver by switching cable (as Dan suggested) but I missed something. Thanks Dan , I re-checked.

It’s odd that only one channel of the many sources is intermittent. Radio, cd, phono all work fine. Tomorrow I’ll dig into the aux connection my tv is connected too.

I’ll let you know when I find something.


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 Post subject: Re: Weird audio output matching issue
PostPosted: Apr Thu 11, 2019 12:16 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 20366
Location: Utica, NY 13502 (USA)
What is the make and model of your amplifier?

Dave


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 Post subject: Re: Weird audio output matching issue
PostPosted: Apr Thu 11, 2019 7:58 pm 
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Joined: Aug Tue 04, 2009 2:15 pm
Posts: 355
Location: Elmira, NY
My receiver is a Yamaha RX-830. Stereo surround Sound.
I have 3 pair of speakers and a powered subwoofer.
Today I pulled all input connections, sprayed de-oxit into all the jacks, there were a lot of dust and some corrosion on both the suspect plugs and jacks. Presently it’s working but it’s only been a hour. Maybe I got lucky. I hate intermittents.


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 Post subject: Re: Weird audio output matching issue
PostPosted: Apr Thu 11, 2019 9:16 pm 
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Joined: Feb Thu 28, 2019 7:48 pm
Posts: 250
Location: Lawrenceville, Illinois 62439
"I hate intermittents"
Back in 1975, when my oldest brother got his E.E. degree and started working for Motorola in Chicago, he drove home one weekend in a new car. Took dad for a ride and showed him all the options. When he mentioned intermittent wipers, dad didn't quite get why anyone would choose such an option, having battled them for 25 years at the time.
Dan


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 Post subject: Re: Weird audio output matching issue
PostPosted: Apr Thu 11, 2019 10:30 pm 
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Joined: Aug Tue 04, 2009 2:15 pm
Posts: 355
Location: Elmira, NY
Lol, it sure is humbling. After almost 70 years of troubleshooting, some times the simplest problems can stump oneself.

I’ve come too far to be upset with, “is it plugged in?”.

So far, so good. 4 hours no problem.


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 Post subject: Re: Weird audio output matching issue
PostPosted: Apr Fri 12, 2019 3:09 am 
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Joined: Sep Mon 16, 2013 2:42 am
Posts: 3288
Location: Tucson, Arizona U.S.A.
Try wiggling the plugs to see if it quits again. This is to check for a broken solder joint where the jack connects to the PC board.

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Jim Mueller


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 Post subject: Re: Weird audio output matching issue
PostPosted: Apr Fri 12, 2019 5:33 am 
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Joined: Jul Fri 18, 2008 10:02 am
Posts: 2104
Location: near ST Louis Mo 62002
<a href="https://imgur.com/aweFBxv"><img src="https://i.imgur.com/aweFBxv.gif" title="source: imgur.com" /></a>
Image

What model is your TV , most every thing has a digital or optical ( toslink ) output that you can use directly to your yamaha receiver .

I have a Yamaha RX A700 and use the digital out from my tv to my receiver , which your receiver also has .

You would also get much better audio this way!

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Mark
(Conti the brain damaged robot )


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 Post subject: Re: Weird audio output matching issue
PostPosted: Apr Wed 17, 2019 2:45 am 
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Joined: Aug Tue 04, 2009 2:15 pm
Posts: 355
Location: Elmira, NY
Well, as it turns out, the problem was in the connections. It’s been several days and no audio is cutting out.

I cleaned up the connections, and put on some anti corrosion compound and the problem went away. I would never had guessed it, there was no visible corrosion.

I’ve never tried the optical connection cable. I’ll look into it.


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 Post subject: Re: Weird audio output matching issue
PostPosted: Apr Wed 17, 2019 9:55 pm 
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Joined: Nov Fri 10, 2006 12:24 am
Posts: 2314
Location: Thornhill, Ontario, Canada
Y2KEDDIE wrote:
Well, as it turns out, the problem was in the connections.
Always check the cables and connectors first! Been there many times...
Cheers,
Roger

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Thornhill, Ontario
Ontario Vintage Radio Assoc. http://www.ovra.ca


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 Post subject: Re: Weird audio output matching issue
PostPosted: Apr Thu 18, 2019 12:10 am 
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Joined: Jun Wed 08, 2011 2:33 am
Posts: 8707
Location: Ohio 45177
Yea I would not have thought "loading" with a headphone output going to a line-in, as most line inputs are much higher impedance than headphones are, and would not load it at all in comparison. So it was the fact that the connections and or cable are mass products from somewhere or other..... :?

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 Post subject: Re: Weird audio output matching issue
PostPosted: May Sat 11, 2019 4:32 pm 
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Joined: Nov Wed 30, 2016 7:35 pm
Posts: 4358
Location: Sunbury, Ohio 43074
Anyone who has ever serviced anything just LOVES the single word "intermittent". :). It was always particularly annoying when servicing anything for a client (in other words, not yours). How much can you charge when it takes you 4 days to track down a 39c part that fails intermittently.

Glad that phase of my career ended long ago.

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