Fickle TV on startup!

Good evening,

For me, it's a capacitor that is about to die. I've encountered this problem before.
I manage a computer park, and I've systematically started repairing malfunctioning screens just by replacing the faulty capacitor(s). It's true that generally, it's visible (a "bulging" capacitor), but I've come across a few cases where it was almost invisible (just a slight curve on top)...
And in some rare cases, I've replaced all the capacitors (the ones related to the power supply, there are about 4 on a PC monitor, and it should be roughly the same for TVs) because I couldn't see any faulty capacitor and it worked.

But generally, since it usually starts with a temperamental screen, I'll check that side... The capacitor charges and sends the "juice", it is especially useful at startup (from what I've seen). When it shows signs of weakness, it doesn't charge enough for the screen to turn on.

This is just my experience, I'm not an electronics expert...

Good luck.

Good evening Sebbonard,

Thank you for your response! So you think it could still be the capacitors.
I've seen pictures of faulty capacitors in other threads, and it's pretty obvious, but on my TV they look fine, though I could be mistaken.

Let's say I replace them (but I’m a total beginner in electronics... I'm already wondering how I'm going to desolder the old ones and what to replace them with... I haven't touched a soldering iron since my tech classes...) But well, I can't afford to have my TV repaired by a pro. (who's asking me for €50 just for a quote... yay.. -> go die).

To get to the question, I've seen that many people replace them with "stronger" caps to prevent them from blowing in the future.

In my case, if the electrical installation is faulty, would a stronger cap mean it consumes more, I suppose? Or will it only draw the necessary power, no matter how far the capacitor can go? I don't know anything about this field..

Anyway, I'm going to lend my TV for a few days to see if the issue is with my electrical installation or the TV itself.
But if it does the same thing, and the TV has a problem, I'll have to look into it, so regarding the question about capacitors, I'm very interested.

Thanks anyway, if we find a solution I'll post about it, it might help others for sure.

Good evening

unfortunately, a well-known issue with Samsung televisions.
it's definitely the capacitors.
if you want to replace them yourself, go to a TV repair shop and ask for capacitors for Samsung. The guy, if he's serious, should be well aware of the problem and will give you the right parts for the price of a loaf of bread.

As I was saying, I often replace capacitors. I've been soldering since I was little (thanks, Dad)... That's why I don't understand why I still can't get it right :(... My solders are never very neat, but they work.

For the capacitors' voltage, I tried to get back into electricity, but that's the thing, at home, that blocks me... I can't manage.

When I replace a capacitor, I always take the same specifications. I even started salvaging old capacitors from broken machines...
Since I saw that it almost always worked, I thought I would invest in new capacitors... And then I realized that I had been wasting my time (because, you'll see, if you get to it, removing old capacitors can be a hassle)... it costs nothing for a capacitor (10, 20, or 30 cents, I can't remember).

For the voltage, I think some (more knowledgeable in Electronics) can give you advice. Otherwise, as dany311 told you, ask for advice from a repairman (if he's serious :), some of them can be a bit dodgy...). Electronic component sellers are often enthusiasts, they'll advise you too.

As for the anecdote:
If I started looking at the capacitors of all the broken devices, it's because one day, my dishwasher broke down. A guy came and told me it needed to be replaced... I was so frustrated...
Once he left, I still had a look... There was nothing behind, but underneath, there was a small recess with a little circuit board (I thought it was packed with electronics!!) and a big round thing (big as the large round batteries) from which a sort of melted plastic was coming out (a big capacitor, I learned later)...
I took it out (it wasn't soldered, just fitted in like a light bulb) and took it to a spare parts shop for home appliances... I didn't even have time to say anything, the guy said, "Your machine must be working much worse?"...
Repair price: €5 (roughly)
Repair time: like changing a light bulb (+ the trip, if you don't have a bulb in stock)

And when you recap all this, between the manufacturers who cut costs and use low-quality components and some repairers or technicians (not all, don't get me wrong) who forget to check... There's plenty to complain about...

Thank you for the answers :)

I'm going to try this weekend to take my TV to my brother's place to leave it with him for a while and get some feedback.

Since I moved here, I've already had a disastrous phone line that had to be changed, and a lousy signal via the TV antenna cable... So a faulty electrical network wouldn't surprise me either... (I have new neighbors; could it matter if they have a lot of electrical devices?) *noob question level 10*

It's just that I see no logic in my TV's malfunctioning... sometimes I turn it on and it's fine, I put it in standby, I turn it back on and it doesn't work anymore... I unplug it for 10 minutes and plug it back in and it works again, (if I turn it off, it won't turn back on) and it also depends on where I plug it... Sometimes it works plugged into the kitchen, and not in the living room, and vice versa. It's a TV that makes you go crazy, actually.

Anyway, I'm going to give it a vacation, and if it still acts up, I'll change the capacitors, praying very hard not to mess it up even more considering my knowledge of electronics and my legendary soldering skills. (more used to burning bits of wood because I thought it was funny as a kid... lalala..)

I'll share my adventure, which might help young beetles with wayward TVs!

Good luck to you

Good!

TV tested elsewhere than at my place, same problem.
So I changed the capacitors, I replaced them all... since the original ones looked fine, I wanted to make sure I changed the culprit.
2 1000uf 35V, 2 1000uf 25V, and 2 1000uf 10V all at 105C from Rubycon.

And the problem is still there u_u after reassembly, I turn it on, the LED blinks 4 or 5 times, then 10 seconds later the TV turns on.
I turn it off, to try to turn it back on, and it doesn’t turn back on (neither does the LED)
Anyway, just like before changing the capacitors.

Do you have any other leads?

Too bad,

My skills stop at capacitors... Sorry.

I’ll still give you 2 leads (to be taken with a grain of salt) based on my experience with breakdowns at work.

- On laptops, there can sometimes be an issue with the inverter board. There’s probably one on an LCD TV. This results in a black screen (sometimes you can see a bit of the image if you look closely). However, I'm not sure because it seems to me that if this board is "dead," you shouldn't be able to turn the screen on at all.

- Since the LED doesn’t light up, and you don’t have sound either, I would rather target the power supply... And probably one of its capacitors as well.

Of course, on a TV, it's integrated and changing a capacitor (or even repairing it yourself) in the power supply... It's pretty risky, even dangerous.

I once tinkered with a PC power supply (because I couldn't find one that fit) at work, it worked, but I never dared to put the computer back in circulation...

All of this, as I said, should be taken with a grain of salt. If any pros come by, they will surely tell you more.

Good luck!

Thank you Sebbonard,

Indeed, I've read on some forum that they were talking about "inverters". Well.. I have absolutely no idea what that is. However, my TV turns on when it's been unplugged for a long time.. like overnight, the next day it turns on, but just once a day (you have to choose your program wisely)
Once it's on, it can hold on for 24 hours.. But since I'm not working at EDF.. I have to turn it off.

In short, it's really a problem at startup.
From what I’ve read, after the capacitors, I would also suspect the power supply. I also think it can be dangerous for a novice to mess with the power supply but well.. A friend is coming over with a multimeter, he knows better than I do so I'm waiting for his verdict.

If he doesn’t have anything concrete to tell me, I’ll post a picture of my TV’s motherboard, hoping you can help me pinpoint the power supply, from where the problem probably comes (I don’t know where the power supply is on the motherboard)

And then I'll still tinker with it because I'd really like to fix it. I can't pay 250€ or more for a professional repair, and I'd like to give it a second life because in the end, it's probably something silly.. too expensive to repair, and too silly to throw it away.

Thanks again for taking the time to help me, it's really nice! My friend is supposedly coming over Wednesday night, if he finds the problem I’ll let you know. If he doesn't find anything, I’ll post a picture, hoping you guide me towards the possible power supply issues :)

Wait and see!
Big thanks for your support Sebbonard!

(Imitatia)
I don't know why I can't change my username, but anyway, it's Imatatia.
In the end, the problem probably comes from the power supply.

Simple test (might not be very secure, but whatever) once the TV's cover is removed, there are two boards, the one with the power supply, the capacitors, etc., and the one with the input/output (antenna, HDMI, etc.).

When I connect only the main board, the TV powers on for sure (the screen lights up)
If I reconnect this board to the video input/output board, it turns off. Same symptoms as before.

I conclude that the second board is demanding too much power and that the first one has a dying power supply that can't provide enough anymore.
Am I right in your (my) opinion?

I don't see how to find the problem and fix it, so I'm thinking of buying a complete board (about €65), but before that, I would like an opinion that confirms or denies my assumption because €65... if it's not that, ouch.

Could the problem be with the input/output board? The first one would provide enough power, but the second could have an issue? (If so, I will never solve this TV problem)... In any case, no visually damaged components.

Hello,

Well, it's a mess.
If anyone is still interested and has any ideas.. u_u

After changing the capacitors, which weren't the problem, I replaced the whole board with a new one thinking it was a power supply issue. As explained in the post above.

I'm still at the same stage. It doesn't work.

I hesitate to change the second board, the one with the inputs. Since I've already spent 90€ on unnecessary expenses between the capacitors and the power supply board..

Since the screen lights up when the power supply board is not connected to the input board and the power supply is ruled out now.. Could the problem be with the input board?

That seems to be the most logical thing or am I going off track?
It's going to be hard to find that one too.. :/

If you have any suggestions, I'm all ears, and if you want to throw stones at me, go ahead *so fed up*

Good evening to you