Insignia No AV, Demonic sound coming from panel possibly

[k0nsol]

Hi All!

I've recently been trying to get into TV repair (mainly for the fun of it/side hobby), and to better my lack of component level repairs. I work IT and am contently given broken electronics, usually which I try to fix for fun. In the past, I've thrown parts at the TV based until It works. Usually I'd sell it at a major loss after that, as a man can only have so many TVs.

I saved a Insignia NS-p502Q-10A from the curb earlier this week, and think I've diagnosed it down to a short to ground on the input board. I checked all the outputs on the power supply, and verified that both the X and Y mains are receiving the proper power, as well as the suspect input board. I also ran a continuity test across the buffers, which came back negative.

On the input board, I don't receive the noise if I unplug the main connector to the control board. Additionally, the main IC after 30 seconds or so gets extremely hot, to the point where I can barely keep my finger on it.

Here is a video of the noise:

https://drive.google.com/open?id=1ZD...PuSVLnc6hWLJ3X

Advice on what to check next is much appreciated!

[llonen]

Re: Insignia No AV, Demonic sound coming from panel possibly

You have posted almost none of the required information to get help and you repair underway, please refer to guidelines for obtaining help with plasma sets. Post reasonable pics of the whole rear set board layout and picks of the individual boards in the set for a start. Test VA and VS referring to panel spec, Test Vsc, Ve etc also see if Vs and VA have shorts to ground on either sus board.

Now that said, what I can see of your set and a search on NS-p502Q-10A seems to suggest this is a Samsung with a different badge, so you could try the following remove the flat cable from the Logic CTRL Board to the Signal input board then jumper pins three and four on the Logic CTRL Board. This should produce a test pattern on the pdp if everything else is working correctly.

Let me know how you get on

[tvtimmy]

Re: Insignia No AV, Demonic sound coming from panel possibly

Does the screen light up at all?

[k0nsol]

Re: Insignia No AV, Demonic sound coming from panel possibly

Hi All,
The model is a NS-P502Q-10A. I've attached pictures of the TV as well.

Shorting pin 3/4 did not display a picture. One interesting thing I found was that with the power (and control/data cable) disconnected, the TV did not make any noise. When connecting only the power cable from the PSU to the input board, the TV powered up/on and continued making the noise. Additionally, the input board needs to be connected to power, and power only for the IR to work.

The IR works normally. The TV powers on and off via a remote.

[k0nsol]

Re: Insignia No AV, Demonic sound coming from panel possibly

Also, to answer TVTimmy, The screen doesn't display anything or power on. No image or backlight.

[Andrew F. Ali]

Re: Insignia No AV, Demonic sound coming from panel possibly

Unplug the PSU from the Main Bd and see if you have 5VStd-By power on the removed connector.

[k0nsol]

Re: Insignia No AV, Demonic sound coming from panel possibly

If by main bd, you mean the input board, I have one pin labeled "STBY", which does have 5v at the "off" state.

[k0nsol]

Re: Insignia No AV, Demonic sound coming from panel possibly

Any thoughts? I'm thinking since the input/main board's data line isn't connected, and I'm having the same symptoms, that the control board is the culprit

[tvtimmy]

Re: Insignia No AV, Demonic sound coming from panel possibly

Is the sound coming from the speakers?

[k0nsol]

Re: Insignia No AV, Demonic sound coming from panel possibly

It sounds like it's coming from the panel it's self. both speakers are completely disconnected.

[k0nsol]

Re: Insignia No AV, Demonic sound coming from panel possibly

Lost cause?

[budwich]

Re: Insignia No AV, Demonic sound coming from panel possibly

when you say the "the panel itself" are you meaning the "physical panel" or one of the boards on the panel is making the sound? ... I can't tell from the video.

Use a paper towel card board tube or otherwise to your ear and see where you can isolate the sound from and go from there.

Further, on some designs (panasonic in particular) have grounding issues which may generate buzzing....BUT this "fault" ultimately takes out some of the components as the grounding is lost to some of the FETS used to power the display.

The voltage labels on the power card are not legible... can you improve and identify which you have checked. Same for the main board.

[petehall347]

Re: Insignia No AV, Demonic sound coming from panel possibly

sounds like switching noise from supply . is it drawing excess current from the wall ?

[R_J]

Re: Insignia No AV, Demonic sound coming from panel possibly

If you here the noise from the panel itself it is likely because the panel has lost its gas, either it is cracked or the glass has lost its seal (around the edge) About the only way to confirm it would be to look at the drive signal on the buffers.

[k0nsol]

Re: Insignia No AV, Demonic sound coming from panel possibly

I fully disassembled the TV and found the edge of the front glass. The noise appears to be originating from the Plasma panel it's self, not from any of the individual components.