Toshiba 50" Fire TV Edition ~ Model #50LF621U19

[DeatRaton]

Hello I'm new to this TV repair hobby, I got curious as to how these devices actually function. I've watched some videos and i have taken apart my own televisions and put them back together just to see how difficult it would be. Long story short I purchased a newer TV with a blank/dark screen just to figure out the issue but so far I am stuck and wondering if someone would give me some tips or at least send me on the right direction to figuring this out.

I have a 50" Toshiba 4k Fire TV Edition. The LED lighting is working, sound is working as well but no image on the screen. I have tried to hold a flashlight to the front of the screen and I do not see any image what so ever. I've brought the menu option up and still do not see anything. I've checked the boards for possible burn marks or blown capacitors and everything seems just fine with no issues. After some testing these are results I am getting as far as the power board while TV is on.

1. 16VA - 16V
2. 16VA - 16V
3. 12V3 - 12V
4. 12V3 - 12V
5. 12V3 - 12V
6. 12V3 - 12V
7. GND - 0
8. GND - 0
9. GND - 0
10. GND - 0
11. 5V2 - 5.1V
12. 5V2 - 5.1V
13. PWON - 3.9V
14. 5V1- 5.1V
15.DIM - 5.0V
16. BLON - 5.1V

I m not sure if I am testing the LED driver correctly but from testing the negative and positive LED connection pins I got 119V.


So now I am stuck and do not know what my next steps would be. I blindly want to say T Con board out of a wild guess but then I really don't see why it would be the problem. I'm confused and would appreciate some guidance. Thank you. ����

[diif]

Re: Toshiba 50" Fire TV Edition ~ Model #50LF621U19

If the backlights are on as per photo 3 they don't need testing.
There is a fuse on the tcon F101, can you measure the voltage each side of it ?

[Michale32086]

Re: Toshiba 50" Fire TV Edition ~ Model #50LF621U19

So now I am stuck and do not know what my next steps would be. I blindly want to say T Con board out of a wild guess but then I really don't see why it would be the problem. I'm confused and would appreciate some guidance. Thank you. ����

In layman's terms (and probably not technically accurate) the Main Video Board creates the display/picture and sends it to the TCON.. The TCON "assembles" (for lack of better term) the display/picture and sends it on to the panel boards which actually puts the display/picture on the panel.. I know this is not a real technical explanation, but it is sufficient for my purposes..

If the TCON board is damaged, the display/picture cannot transfer to the panel... First thing is, check the fuse on the TCON..

If the TCON is OK, then the problem is likely in the panel boards.. Unfortunately this is more likely than not un-repairable..

Put the TV on it's back with the display panel facing up..

VERY CAREFULLY remove the plastic bezel.. Most likely there won't be any screws to remove, just unclip the bezel from the frame..

***BE VERY CAREFUL OF THE TABS***

There are cellophane tabs that extend from the bottom of the panel and connect to long thin circuit boards.. Possibly from the sides as well but without any boards.. You do not want to rip any of these as that will destroy the panel beyond all hope of repair..

Once you have the bezel off, very carefully inspect those long thin boards for any shorts or burns..

If there are no shorts or burns, then the only thing left to do is to replace the TCON.. Fortunately, the TCON is usually a very inexpensive parts ($20 +/-)..

If there are shorts or burns on the panel boards, get a good toothbrush and alcohol (the rubbing kind.. No need to waste a good whiskey on this. ) and clean the area... It's unlikely to help, but stranger things have happened..

When disassembling down to the bare panel, take things slow and easy.. Have a work table large enough to handle the entire TV without anything hanging over the edges.. Loose shirts should be avoided as they present a snagging danger.. Ideally, have a table away from the wall so as to give you complete 360 degree access to the TV w/o having to reach way over..

I am not at my shop yet.. I can follow this up when I get to my shop in a couple hours with pics of what the tabs and panel boards look like..

Good luck.. Few things are more rewarding than bringing a really nice TV back from the dead...

OK OK.. MANY things are more rewarding, but it's still a nice feeling...

[budm]

Re: Toshiba 50" Fire TV Edition ~ Model #50LF621U19

If you do get 12vdc on each end of the T-CON fuse with ref to the chassis Ground then try having ribbon cables between T-CON board and the LCD panel connected one at a time to see what you will see on the screen.

[DeatRaton]

Re: Toshiba 50" Fire TV Edition ~ Model #50LF621U19

If the backlights are on as per photo 3 they don't need testing.
There is a fuse on the tcon F101, can you measure the voltage each side of it ?

The reading I got from the F101 was 12.9V

[DeatRaton]

Re: Toshiba 50" Fire TV Edition ~ Model #50LF621U19

In layman's terms (and probably not technically accurate) the Main Video Board creates the display/picture and sends it to the TCON.. The TCON "assembles" (for lack of better term) the display/picture and sends it on to the panel boards which actually puts the display/picture on the panel.. I know this is not a real technical explanation, but it is sufficient for my purposes..

If the TCON board is damaged, the display/picture cannot transfer to the panel... First thing is, check the fuse on the TCON..

If the TCON is OK, then the problem is likely in the panel boards.. Unfortunately this is more likely than not un-repairable..

Put the TV on it's back with the display panel facing up..

VERY CAREFULLY remove the plastic bezel.. Most likely there won't be any screws to remove, just unclip the bezel from the frame..

***BE VERY CAREFUL OF THE TABS***

There are cellophane tabs that extend from the bottom of the panel and connect to long thin circuit boards.. Possibly from the sides as well but without any boards.. You do not want to rip any of these as that will destroy the panel beyond all hope of repair..

Once you have the bezel off, very carefully inspect those long thin boards for any shorts or burns..

If there are no shorts or burns, then the only thing left to do is to replace the TCON.. Fortunately, the TCON is usually a very inexpensive parts ($20 +/-)..

If there are shorts or burns on the panel boards, get a good toothbrush and alcohol (the rubbing kind.. No need to waste a good whiskey on this. ) and clean the area... It's unlikely to help, but stranger things have happened..

When disassembling down to the bare panel, take things slow and easy.. Have a work table large enough to handle the entire TV without anything hanging over the edges.. Loose shirts should be avoided as they present a snagging danger.. Ideally, have a table away from the wall so as to give you complete 360 degree access to the TV w/o having to reach way over..

I am not at my shop yet.. I can follow this up when I get to my shop in a couple hours with pics of what the tabs and panel boards look like..

Good luck.. Few things are more rewarding than bringing a really nice TV back from the dead...

OK OK.. MANY things are more rewarding, but it's still a nice feeling...

I will be checking this next thanks for the details I really appreciate it. Like I said lucky I have broken down my 2 tvs to get some experience before I tackled this project so I will be extra careful.

[DeatRaton]

Re: Toshiba 50" Fire TV Edition ~ Model #50LF621U19

If you do get 12vdc on each end of the T-CON fuse with ref to the chassis Ground then try having ribbon cables between T-CON board and the LCD panel connected one at a time to see what you will see on the screen.

Tried unplugging one ribbon board at a time and same results no image on screen what so ever.

[diif]

Re: Toshiba 50" Fire TV Edition ~ Model #50LF621U19

The reading I got from the F101 was 12.9V

Both sides ?

[DeatRaton]

Re: Toshiba 50" Fire TV Edition ~ Model #50LF621U19

If you do get 12vdc on each end of the T-CON fuse with ref to the chassis Ground then try having ribbon cables between T-CON board and the LCD panel connected one at a time to see what you will see on the screen.

Tried unplugging one ribbon board at a time and same results no image on screen what so ever.

[DeatRaton]

Re: Toshiba 50" Fire TV Edition ~ Model #50LF621U19

Both sides ?

Yes on both sides got 12.9V

[Michale32086]

Re: Toshiba 50" Fire TV Edition ~ Model #50LF621U19

I will be checking this next thanks for the details I really appreciate it. Like I said lucky I have broken down my 2 tvs to get some experience before I tackled this project so I will be extra careful.

If you do have to remove the panel, get yerself a pair of these..

They make the job INFINITELY easier..

[DeatRaton]

Re: Toshiba 50" Fire TV Edition ~ Model #50LF621U19

If you do have to remove the panel, get yerself a pair of these..

They make the job INFINITELY easier..

The panel boards are clean, no burn marks what so ever the tabs all look to be in tact and great shape. This is a 2018 TV so everything looks crazy clean. At this point could it be the TCON or the Main Board?

[vinceroger69]

Re: Toshiba 50" Fire TV Edition ~ Model #50LF621U19

if a replacement tcon is cheap i would try one in the set atleast it will rule it out.

[Michale32086]

Re: Toshiba 50" Fire TV Edition ~ Model #50LF621U19

if a replacement tcon is cheap i would try one in the set atleast it will rule it out.

What he ^^^^ said

It could be the Main Video Board.. But a TCON is likely 10-20 bucks, so it's a small price to pay to eliminate that possibility..

[DeatRaton]

Re: Toshiba 50" Fire TV Edition ~ Model #50LF621U19

Sounds good I will try that

[DeatRaton]

Re: Toshiba 50" Fire TV Edition ~ Model #50LF621U19

Hey guys so I ordered a $10 TCON board from Ebay, it was inspected by the seller with a 99% seller rating.

Did the job for me. Got the TV for $30 and payed $10 for my TCON for a nice fire tv edition toshiba 50" I thank you guys for all your help.
📺🔥🙏😁

[nomoresonys]

Re: Toshiba 50" Fire TV Edition ~ Model #50LF621U19

Good to hear, thanks for the feedback.

[vinceroger69]

Re: Toshiba 50" Fire TV Edition ~ Model #50LF621U19

Hey guys so I ordered a $10 TCON board from Ebay, it was inspected by the seller with a 99% seller rating.

Did the job for me. Got the TV for $30 and payed $10 for my TCON for a nice fire tv edition toshiba 50" I thank you guys for all your help.
📺🔥🙏😁

Glad to hear a replacement tcon fixed the issue its nice too have a nice easy fix at times