Question

LG TV behaves strangely when first turned on

I have a LG 42LC7D TV, and it has been working pretty well except that it stopped being able to save the channels, and it had to search for channels every time it was turned on. We have a set top box from our cable company now, which takes care of saving the channels, so that doesn't matter now.

What does matter, though, is that whenever the TV is turned on now, it makes a noise -- similar to the sound of a VCR rewinding a tape -- for anywhere from a few seconds to a couple minutes, and then it goes away.

A couple days ago this rewinding sound was accompanied by the screen flashing like a strobe light slowly, but after about 30 seconds to a minute, everything was normal. The TV has not flashed when turned on since.

I have to say that one time several months ago, I turned on the TV and there was no sound. Turning the TV off and then on again fixed this problem, and we haven't had an issue since.

I wondered whether or not these things might be symptoms that the TV will eventually die, or whether or not these things are normal for LCD TVs. I know that these problems have not always existed. I think the rewind noise might have been happening for about a year or so.

Again -- the noise goes away after a little bit of being on. I think a couple days ago was the first time that I had seen the flashing, and it hasn't done the flashing since.

Anyone know what might be causing the problems, and what it might mean for my TV? Thanks.

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Clarification Request
Isn't this a set from 2007?

My bet is a mainboard and/or a power board failure. At this age plus it's only a 720p TV I suggest you not repair this. If you scan for channels how about an external tuner and connect the tuner via HDMI so the external tuner "fixes" that part of the problem?

Example at https://www.amazon.com/Converter-ViewTV-Recording-Function-Composite/dp/B01BO61CMS

There are many tuners like this that take an antenna input and HDMI out. Sorry but I don't sell or promote these so I can't answer much more but if I wanted a cheap fix, this might be it.

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It was manufactured in January 2008

It has a January 2008 manufacturing date on it, so I am assuming I got it sometime in 2008.

Sorry for the misunderstanding -- the tuning issue isn't the main concern. That was just a problem that developed with it early on. It isn't an issue now because it is hooked up to a set top box that keeps track of all the channels that way.

The issue I was asking about was the strange noise and the picture behavior when the TV is first turned on. I was wondering what might be causing that issue, and if it was something that people have seen before, and if it might be a symptom that the TV might die sometime soon.

Yeah, I wasn't going to get it repaired. I was just curious if I needed to be looking at getting a new TV soon, or if it might last another couple years. I am going to hold onto it as long as possible, as newer products don't seem to be as well made as the older products.

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Noises. Usually....

For electronics to make noise, something has to move. If it's not the speakers it's usually some coil. TV techs for decades would carry a can of "coil silencer" which is almost always shellac that is thin enough to penetrate coil windings. After it dries the coil can't emit the noise. Now there were some that demanded the coil be replaced but today that isn't done and the fix is a new board. Given the age I would not do that either because of cost or there are no boards to be found.

As to predicting product failure by this noise, that's not a sure sign.

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so that would just cause a noise for a few seconds?

Thank you. I don't know whether or not the problem has to do with the speakers on the TV or not. Like I said, it only makes the noise when the TV is first turned on each time, and the noise sounds like the rewinding of a VHS tape. The sound only lasts for a few seconds, but I was just curious.

Hmmm....interesting about the coil.

Thank you.

What about the flashing that I experienced several days ago that happened at the same time as the noise. Would that be more likely to make it the speakers or the coils or something else? (I only noticed the flashing once. I don't think it did that before, and I don't think it has done it since. I know it didn't do it last night when I turned on the TV).

When it was doing the flashing at the same time as the noise, I think both the noise and the flashing lasted for about a minute or so, and then both stopped at the same time, and the picture and sound were normal for the rest of the night.

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Remember that noise would be from things that move.

And as the electronics start, it may be either the capacitors pull more as they charge up or something warms up and by expansion fills the void that let it move.

My background included root cause diagnosis on military hardware so getting to the bottom of this could be time consuming. Here I will share the most likely with stories.

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Yes, that would be interesting

Thanks.

I don't necessarily need to get to the root cause of it -- as I don't think that will be possible.

What you said does help me to understand a bit.

The startup issue is annoying, but I can tolerate it, as long as the TV continues to work, and as long as the problem continues to go away after a few seconds of it being on.

I just wanted to know if anyone else had experienced anything similar, or if anyone had an idea what might be causing it. You have been helpful.

I would be interested in hearing the most likely stories/suggestions for what may be causing it.

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To answer the question.

Yes, I've worked in electronics since the 60's. My advice is shellac or coil silencer to the coils where the noise is coming from (very common issue dating back decades and to this day.)

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Thank you

Thanks for taking the time to answer my question. I appreciate it Happy

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