Riddled TV Repair Forum

Rockmore · Joined: 14 Dec 2009 Posts: 3

I have a JVC 27S33 TV with RCA component outs on the back. The audio out all of a sudden puts out a audio hum regardless what amp or receiver it's connected to.

Have tried everything to try and isolate the problem: changed location/outlets, RCA cables and types, etc etc. It's definitely with this TV's audio out. There is no other problems what so ever including audio using the little speakers in the TV itself. It's just the RCA audio outs (putting out a hum with the audio signal).

Have dissembled the unit several times, and everything is on one main circuit board, with a additional small circuit board on the back of the CRT neck itself. Solder connections all look shinny and clean where the audio out RCA female jacks are. There are absolute micro size resisters in solder joints extremely close to the RCA joints.

What to do to get rid of the hum?

Thanks
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Jesse Mack · Joined: 22 May 2008 Posts: 600 Location: The Last Frontier

Do you have the Hum with no RCA jack inputs at all being connected and using the RF input and the sets internal speakers?

Jesse

Rockmore · Joined: 14 Dec 2009 Posts: 3

No. No hum with no RCA jack inputs at all being connected and using the RF input and the sets internal speakers.

Just like when the component rcs'a are hooked up, there is no hum from the internal speakers at all.

The audio outs' do not work either (naturally) using a RF input only.

Jesse Mack · Joined: 22 May 2008 Posts: 600 Location: The Last Frontier

You most likely do not have a TV problem. A RCA type plug with an open ground will cause a hum when going to a reciever. Usually you do have audio on the audio output jacks when using RF.

Its kind of like this. Its the reciever that is producing the sound and if there is no hum when not using the reciever you either have a bad cable, bad reciever or have it hooked up with a ground loop.

With no offence intended, use the owners manual and make sure you are not creating a problem by hooking the input to the output in some way.
Use one cable at a time and one input to the reciever at a time to isolate. and then try a different cable to the same input.

If your cable has an internal break in the ground or center conductor you can get a hum.

I have also seen recievers that will hum if the AC plug is reversed.

Good Luck

Jesse

Rockmore · Joined: 14 Dec 2009 Posts: 3

Believe me, its the tv audio outs.

As I tried to state originally, I already spent two full days "isolating" the hum. Everything from changing the wall outlet (yes I even did it three different times and ways to reverse the AC polarity, with and without the ground, etc). Re cabled everything, sometimes even using three different rca cables to a single input or output. My dozens of different high grade audio rca cables are all just fine.

On a about 15th different cabling configuration, completely removing the tv's rca audio outs, from anything to do with anything else or the amp(s), everything was just fine. So.. I re did everything on the 16th and 17th times putting tv's audio out singularly to a input or amp(s) input, and the hum was there. On a 18 try, even moved the tv to a completely isolated outlet completely away from anything else (one good sole outlet to it's own circuit breaker) with a THIRD reciever, and there it was. Hum from the tv audio out alone still. Internal speakers even at max volume had no hum at all.

I made a slight mistake in the last reply- did have a audio out signal from the tv when the RF antenna in was used in lieu of the component cable.

So.... I'll state this again: Have dissembled the unit (tv) several times, and everything is on one main circuit board, with a additional small circuit board on the back of the CRT neck itself. Solder connections all look shinny and clean where the audio out RCA female jacks are. There are absolute micro size resisters in solder joints extremely close to the RCA joints.

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Jesse Mack · Joined: 22 May 2008 Posts: 600 Location: The Last Frontier

Please do not take offence at what I am going to say as I see so very many people doing so many unusual things that cause unusual problems.

I looked up this model (which by the way is a AV-27S33) and it has only one Audio output. All of the rest are Audio Inputs.You should never have any audio input on your TV hooked to your reciever as it will cause feedback. All audio outputs from your DVD/VCR/CD/CABLE etc should go to your reciever only.

If you do not have any of your audio inputs on your TV hooked to your reciever consider this. The audio output of your tv is a line output only on this set so there is no advantage using this for sound. Your sound source should be your CABLE/DVD/CD etc. Just about the only time you would want to use the audio outputs from your TV would be if you are on a terrestial antenna.

Remember, Yout TV is a simple display device and is not the source.

If you have a hum with all of the inputs disconnected with no audio coming from the source device going to your reciever at the same time acquiring sound from the line output of your tv let me know.

This has all been said due to the fact that there is no hum from the sets own speakers. The sound take off for the line ouputs is the same as the source for the internal speakers.

You might also make sure that from within the sets menu that you are not in SAP mode.

Hope this helps

Jesse