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Question

Adding Aux port to Plasma TV that doesn’t have analog out

Hello experts. I have a 2009 Panasonic Viera Plasma TV that sadly has no analog audio out ports. I want to hook up to my (newer) LG receiver that sadly has no digital in ports. In the past I had a tv with no audio out and I was able to splice into the tv’s speaker system with a female 3.5mm Aux socket and connect it to my receiver.

I did the same thing with this Panasonic, but unfortunately the protection comes on whenever any sound with any type of bass comes through. Is this a grounding issue? (Combining the grounds of both speakers into one on the Aux connector) Or am I doing something wrong?

HELPFUL INFO:
First, the reason I have this combo to begin with is because I was using a smaller tv that had an aux out port before I bought my receiver. I was recently gifted this plasma tv. I didn’t even realize the LG didn’t have an optical in, as I’ve never used a digital connection before.
I originally researched a digital to analog converter, but seeing as how the only electronics store in my city is Best Buy, I don’t have $100 to fork out to buy a converter locally. I priced some affordable converters online, but the performance reviews were too inconsistent and I didn’t want to waste time and money guessing.
I mainly want the tv hooked up to the amp because I’m into music video games - Rock Band, Amplitude, etc., and the tv speakers alone aren’t enough. The additional problem with converters is the extra lag. A few milliseconds isn’t much with watching tv or even most games, but when audio/video timing is at play, it makes a big difference.
Also, i was able to install this connector using parts I already had around the house, so it didn’t cost me anything. I desoldered the wires from an old headphone splitter, and soldered some house speaker wire I had laying around. I used hot glue between all the connections to ensure they wouldn’t touch. Then I covered it in heat shrink tubing - two layers. I spliced into the actual wire of the tv speakers - at different lengths on each wire so that they can’t touch. I didn’t actually cut the wires, but rather stripped back the insulation and wrapped the wire from the aux connector around it. I then put a dab of hot glue over each splice. From there I drilled a hole in the metal plate that covers the input/output board on the tv, just larger than the aux connector, pushed the connector through, and used hot glue on the under side as a brace. For the top side, I added a piece of heat shrink to help stabilize the connector and ensure it wouldn’t push into the tv. It’s an extremely solid connection.

I’ve wired many headphone connectors, both male and female. I’m confident in my work. I’m just not sure what the problem is here. I don’t want to have to add more to my system than I already have, and I feel the fix is probably something rather simple, but unfortunately I don’t have enough experience or knowledge of electronics to understand what would cause this.
Thanks for reading my long post - I’m trying to cover the answers to any questions that may arise, and I appreciate any help that can be given. I can take pics or go into additional detail if needed. Just let me know.

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All Answers

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Answer
This sounds more like an amplitude issue than a ground issue

In reply to: Adding Aux port to Plasma TV that doesn’t have analog out

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Was kind of thinking that...

In reply to: This sounds more like an amplitude issue than a ground issue

I wasn’t sure if that would be an issue or not but it did run through my idea of possibilities. The thing that puzzles me though is that I completely turned off my receiver and then disconnected the aux cord from the connector on the tv, yet it still cuts off. I had to turn the volume very low last night just to watch a movie because it cut off on certain scenes (explosions and what not), and I didn’t feel like lifting that heavy thing off the wall and opening it up again to completely disconnect the add-on.

That’s why I was thinking it may be a grounding issue. It doesn’t make sense to me to have that problem if nothing’s connected to the port. I’m going to pick up a DMM after work today and test everything again. It just dawned on me that the part I used could be faulty or cheap, or the internal parts could have gotten altered from the heat of the soldering iron. I completely forgot that happens sometimes.

As far as the DAC goes, as mentioned before, I’ve read mixed reviews on the cheaper models, and I don’t have the budget right now for a better quality one. Plus there’s still the issue of lag. No sense in purchasing a product that will prevent me from doing what I want to do - the reason I’m even interested in connecting to a receiver in the first place. Because the sound is actually pretty good on these speakers.

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Lag?

In reply to: Was kind of thinking that...

I no longer see lag since makers have been working that issue for years. There are behind the scenes adjustments to compensate for gain or loss in time through the interfaces. Even the speakers get some adjustment behind the scenes.

Moving back to the stereo. If it's going into protect mode without the TV connected then there is some issue over there. I'm declining to get into repair of such things. Stereo amp systems are rarely repaired today as you can find good ones for cheap on Ebay or new receivers near the 100 buck mark that have the optical and more inputs.

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Not the stereo

In reply to: Lag?

I’m sorry, I must have miscommunicated earlier. It’s the TV that’s going into protection mode. And I’ll look into the DAC if lag issues have been addressed.

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OK, one more time.

In reply to: Not the stereo

You'll need an Ohm meter but usually I only need THREE wires. There are four wires to two speakers and two of them should read nearly zero Ohms which will be your ground. So that goes to the ground lug/connection of your new audio output. Then the other two would be your left and right audio connections.

Hope this helps.

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May have found the problem...

In reply to: OK, one more time.

Ok so I picked up a DMM and jumping to the end result - it seems as if the ground for each speaker is not only separate from each other, but also separate from the ground on each of the other connections as well. I’ve never seen this before. So it looks like I’ll either have to find some spare rca connectors or connect two separate mono jacks. I’ll let you know what I discover...

MY TEST RESULTS:
Disconnected both speaker connectors from the board (3.5 jack still connected to speaker wire) - 6ohms across the +/- of each connector.
Disconnected 3.5 jack - 6ohms across each connector.
Tested across both ground wires on 3.5 jack - 1ohm
Tested across both positive wires on 3.5 jack - open
Tested across +/- on each wire going to 3.5 jack - open
Tested across both (+) leads on 3.5 jack - open
Tested 3.5 jack chassis to metal cover it’s mounted in - open
Tested each wire on 3.5 jack to metal cover - open
Tested across speaker ground pins on board - OPEN
Tested across speaker grounds while disconnected from board - OPEN
Tested across speaker grounds while connected to board - OPEN
Tested each individual speaker ground to TV ground chassis - OPEN
Tested individual speaker ground to audio/video ground - OPEN
Tested audio/video ground to TV ground chassis - 0.4 ohms.

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The 6 ohms

In reply to: May have found the problem...

Sounds like the speaker impedance.

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So far so good...

In reply to: May have found the problem...

Just an update, I’ve installed RCA connectors with isolated ground connectors for each side. So far everything seems to be working well. I can’t really crank the volume up at the moment because the neighbors are sleeping. But I’ll test it for a few more days and close out the post with whatever the end result is. Thanks again for taking the time to read about my issues and offer advice.

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