Tv issue

Cyber-Mav · 5 Nov 2023 at 16:46

no shocker here, 5 year warranty expired couple of months back and no the problems start.
over the last month the tv has been baking a loud pop sound when turning on but has worked fine.
since yesterday iv now got an issue where the tv wont turn off. well i can hit the power off button and it goes into standby but powers itself back on again and off and on and keeps cycling unless while its off i hit the power button on the remote to turn it on and it then stays on.
so issue is it wont stay in standby mode and keeps trying to turn on.

anyone know what this issue could be? its a Toshiba 75 incher so its gonna be an issue to take it off the wall for me too. costco has 5 years warranty but Order placed on 04/06/2018 so now its out.

i get the feeling this could be a capacitor issue but again no sure. will probably have to get it off the wall and open it up and check it out.

Cyber-Mav · 5 Nov 2023 at 18:14

aVdub said:
Have you placed model number + type of fault into a search?

yep, its a 75u6763db toshiba 5 and a bit years old. i think it also goes under the name of vestel. may not be common enough for issues.
kiddo says its powered off now so i will go and check. knowing my luck it probably wont power back on lol.

Cyber-Mav · 5 Nov 2023 at 20:45

will get the lid off and check the insides out. will pay close attention to the power board.

Cyber-Mav · 6 Nov 2023 at 08:29

Cost me just over a grand so would have expected it to go 10+ years.
Odd that if its left on it stays on with no issues. Just doesnt want to go off. In saying that it somehow was off all night. Have yet to try turning it on today.

Cyber-Mav · 6 Nov 2023 at 14:09

Armageus said:
Replacing the power board will likely be worth a try - did that on a cheap noname TV before that had issues turning on, and was fine for another 5 years or so (until I was actually ready for an upgrade), was something like £30 for a replacement.

issue isnt turning on. issue is turning off. it doesnt want to turn off. however its not been used today an its been off all night so will test it out later today.

also got to ask now, whats good brand for reliability? samsung, lg, sony etc ?

Cyber-Mav · 6 Nov 2023 at 14:30

Armageus said:
Any HDMI device that could be using CEC to turn the TV back on?

Low batteries in remote? (as can cause random issues)

Does it do the same with a physical power button on the TV vs the remote's power button?

Anything changed with the room layout that could cause stray light/reflections to hit the IR Sensor?

nothing new in the room, tv is connected to nvidia shield tv which i did disconnect to test.
didnt test the physical button need to find where the buttons are iv only ever used it with the remote.
will test tonight and post back

Cyber-Mav · 6 Nov 2023 at 17:18

Will try now

Cyber-Mav · 6 Nov 2023 at 18:44

Same issue, tv turns on but wont turn off iv made a video will upload when i get back home.

Cyber-Mav · 6 Nov 2023 at 19:58

Plot thickens
I left tv on and out of the house wife message me asking if it ok to turn tv on and watch. Interesting looks like if left on home screen tv powers itself off after inactivity time and stays off till remote button is pressed to turn it back on.
Must have been what happened yesterday night since tv was off when i came back in morning

Cyber-Mav · 6 Nov 2023 at 19:59

Also I can't find any physical buttons in the tv. Will chexk the owners manual

Cyber-Mav · 6 Nov 2023 at 20:22

Cyber-Mav said:
Plot thickens
I left tv on and out of the house wife message me asking if it ok to turn tv on and watch. Interesting looks like if left on home screen tv powers itself off after inactivity time and stays off till remote button is pressed to turn it back on.
Must have been what happened yesterday night since tv was off when i came back in morning

Scratch that it was boot looping when i got back so must have been something else

Cyber-Mav · 6 Nov 2023 at 20:25

Diggsy said:
Manual is here - https://toshiba-tv.com//media/a01-m...-internal-75u6763db-10112711_446673488629.pdf

Definitely controllable from the set looking at that…Pages 6-7

I cant see any buttons on it

Cyber-Mav · 6 Nov 2023 at 21:52

The model is right but i dont see any buttons on this tv

Cyber-Mav · 6 Nov 2023 at 22:59

ok i took the tv off the wall and its on the floor now, i found the buttons but no way im gonna be able to reach those with my hand when tv is on the wall.
will take the back cover off tomorrow and take a look inside. should give enough time for the caps to discharge too.

Cyber-Mav · 6 Nov 2023 at 23:05

some pics of the tv while its off the wall:

Cyber-Mav · 6 Nov 2023 at 23:12

Diggsy said:
Can you test it with the physical buttons while it’s off the wall?

did try but same issue

Cyber-Mav · 7 Nov 2023 at 11:00

think i found the problem pics:

the green thingys are popped. i think these are thermistors, cant tell what type and rating they were but found another green one next to another black box same as one in the pic which i think is a relay of sorts so not sure if they were all the same rating.

also extra pics of the boards inside and some closeups:

where to go from here? i can solder and replace them but not sure what spec and type they are unless i just go with the same type that was in the other area of the board. the one green one i found is marked SCK 102

odd i would have thought something blown would prevent the tv from turning on and not from turning off lol. either way finding something popped is good news rather than finding nothing.

Cyber-Mav · 7 Nov 2023 at 12:33

id be inclined to go with a replacement board if the tv did not power on at all. but this is not the case. remember folks the issue is that the tv once turned on wont turn off. now i dont know if thermistors can cause that sort of issue.
iv checked the mosfets with multimeter and not seeing any shorts , the 2 blown thermistors have resistance values of 38.5ohm and 226kohm. the not blown one on the board has a reading of 14.2ohm.

wondering what would have caused them to blow? mains spike? or another failed component on the supply? once tv is powered on it runs non stop so there is that. also looking to get a small extension plug with switch on it to manually cut power to tv, not ideal but damn sight cheaper.

Cyber-Mav · 7 Nov 2023 at 12:37

jaybee said:
At this point it depends how good you are at soldering and what equipment you have. If you can replace those components, it could be as cheap as pence, to find them online or from china. As above though, instead you could just get a replacement board and it's simple unplugging and replugging things back in? I think it's well worth it for £85 personally.

iv got soldering iron kit, iv done fair bit of soldering before mostly tiny smd stuff so everything on this board is huge and easy to do from the looks of it. id like to try a fix before getting a replacement though.
got this going on electronics repair forum too so will keep you guys posted if i make some progress.
back to measuring and testing components on it now.

Cyber-Mav · 7 Nov 2023 at 13:48

Armageus said:
<possible stupid question>
Is that maybe why it's staying turned on, because the relay is staying energised? (because it's failed open?)
</possible stupid question>

ahh, you may be onto something there. looks like the relay thingy has a cap on it with clips should be removable.
checked the two relays with multimeter and seems to similar. dont think the relay stays energised because when it power cycles off it makes the click noise again when its powering back on which means relay is turning off then on again.
now would those blown thermistors cause tv to turn on by itself?