Toshiba 46L5200U flash logo on screen when turn on

[hienton2]

I have Toshiba 46L5200U .. It shows red toshiba logo when turn on ,But instantely dissapear . I think the back light is off.
I search in on internet and finding these tvs have issue of dim line. It has 3.2v at turn on then down to .2v instantely. Bl-on is 3.2 v is ok. TV has sound
Thanks for help

[ransome]

Re: Toshiba 46L5200U flash logo on screen when turn on

I fixed 4 of these , but now I have on that works fine for an hour then turns off , different issue now

[hienton2]

Re: Toshiba 46L5200U flash logo on screen when turn on

Hi Ransome

I heard that fix but It fails after 2 weeks.I am familiar with ccfl back light
but this led I do not know. Can a dead led stop the driver?

[budm]

Re: Toshiba 46L5200U flash logo on screen when turn on

Common failure in backlit LED screen is due to open LED in the LED string, the circuit will shutdown due to no load.

[hienton2]

Re: Toshiba 46L5200U flash logo on screen when turn on

Thanks Budm.

This is good info.Open to check led strips is tough.
I already order inverter $35 on ebay.

[budm]

Re: Toshiba 46L5200U flash logo on screen when turn on

Which one of the power supply board, LED driver do you have?
There are two dimming controls, one is DIM (more likely to be PWM dimming) ,and the ACD for analog dimmming. Which one is being used?
Can I see the whole back side of the TV to see how all the boards are connected?
Do you get the 24vdc output from the power supply board to feed the LED driver board?

[hienton2]

Re: Toshiba 46L5200U flash logo on screen when turn on

Click on this see post #4 My tv has exact same picture
https://www.badcaps.net/forum/showthread.php?t=35468

It has ext dim pin14 CN001 no int dim
yes I do have 24v on both side of fuse
Thanks Budm

[budm]

Re: Toshiba 46L5200U flash logo on screen when turn on

What DC do you get now on PIN14 of the LED driver board if you cut the wire off pin 14? Did you try feeding CN001 with externall 3VDC usinh 100 Ohms resistor to limit the current?
Did you also try disconnecting the cable between the LED driver board and the T-CON to see what happen since this TV has dynamic backlights controledl by the T-CON board?

[hienton2]

Re: Toshiba 46L5200U flash logo on screen when turn on

Hi Budm

The line dim from main board side has 3.2v at turn on then goes down .2v .No matter cut or no cut.
The dim line at CN001 (with cut)has 4v when start and stay4v even led backlight is off.
It will go 0v when turn tv off.

I feed 3.2v to line 14 with cut from main no fix.

I try to remove connector from tcon to inverter , but no fix .

[ransome]

Re: Toshiba 46L5200U flash logo on screen when turn on

Hi Ransome

I heard that fix but It fails after 2 weeks.I am familiar with ccfl back light
but this led I do not know. Can a dead led stop the driver?

What would cause this to fail in 2 weeks?

[hienton2]

Re: Toshiba 46L5200U flash logo on screen when turn on

I have read this from a forum in Canada

" I found that I wasn't the only one that was having issues with the LED back lights. It was mentioned to lift the B/L Dim line, and the B/Ls would stay on. Well, since others had done this,. I did it.

The owner of tv said that his set lasted about 2 weeks, then went out...It didn't last. So, I will never do this "Mod" again". !"

I did not ask him why because I did not register to that forum

[ransome]

Re: Toshiba 46L5200U flash logo on screen when turn on

I have read this from a forum in Canada

" I found that I wasn't the only one that was having issues with the LED back lights. It was mentioned to lift the B/L Dim line, and the B/Ls would stay on. Well, since others had done this,. I did it.

The owner of tv said that his set lasted about 2 weeks, then went out...It didn't last. So, I will never do this "Mod" again". !"

I did not ask him why because I did not register to that forum

So it lasted 2 weeks on just the one the tv not all

[Nick's Tvs]

Re: Toshiba 46L5200U flash logo on screen when turn on

Ransom seems to have fixed 4 of these and has not stated that a single one has failed within 2 weeks. It sounds like the Canadian guy may have just gotten unlucky. I just received one from a customer yesterday, and so far the modification seems to work. My customer wants a full new board no matter what, so I won't have a chance to really test this modification, but I will be holding onto this board in case I see another one of these sets and definitely try this mod if I get the chance. My customer can't pick up his set for a week since he is going out of town, so I will run the tv for that full week 10 hours a day and see if the mod holds or not. I will report back on the results at the end of the week.
Also just so everything is clear but we are talking about using a 80k ohm resistor and shorting pin 15 which should be 2.5 volts to pin 16 which should be 3.25 volts of connector CN2 which is the large connector going from the Power supply to the main board.

[budm]

Re: Toshiba 46L5200U flash logo on screen when turn on

https://www.badcaps.net/forum/showth...6L5200U&page=4

The one I worked on has weak LEDs plus the bad PWM dim from the main board.
http://s807.photobucket.com/user/bud...?sort=3&page=1

[Nick's Tvs]

Re: Toshiba 46L5200U flash logo on screen when turn on

Ok so the new main board came in today, but same exact thing. Removing the yellow wire and or shorting it to pin 16 keeps the back-light on but it stays stuck on full brightness unless I do the mod discussed by budm.
Is this just a bad board? The seller swears to have tested it before sending it over.
Just want to make sure I am not missing something here.
Thanks

[Nick's Tvs]

Re: Toshiba 46L5200U flash logo on screen when turn on

Ok I wanted to avoid tearing this set apart, but it looks like I also have a bad LED on this set, and have no replacement I can use in shop due to the dual LED package. How does one figure out the exact LED this strip uses and where to buy a replacement diode for it?
Any help would be greatly appreciated.
LJ64-03495A and 2012SGS46 seem to be the 2 part numbers popping up for this strip.
Couldn't find any specs on this edge lit led strip but here is one link to where they sell it
http://www.yoycart.com/Product/520801002367/

They are selling these for cheap but I don't want to have to wait for china to send it all the way over. To much shipping time.
Also this is a dual diode, there are 2 led's in each package.


An alternative solution using zener diodes was mentioned in the link below, but I would rather replace the LED with another LED
https://www.badcaps.net/forum/showth...hlight=46TL963


Anyone have any idea what could be a good replacement, and what info I need to provide for this?
Pictures of the strip are attached

[Diah]

Re: Toshiba 46L5200U flash logo on screen when turn on

Anyone have any idea what could be a good replacement, and what info I need to provide for this?
Pictures of the strip are attached

it is LED Modul 7030 6 Volts current 260 mA Lumens 70Lm

look here where i bought and tested 100& perfect

https://www.badcaps.net/forum/showthread.php?t=52847

[Nick's Tvs]

Re: Toshiba 46L5200U flash logo on screen when turn on

WOOO! Thank you just bought the 100 lot!
My next question for you DIAH is how did you figure out this information, and how can I figure this out on my own without having to bother you and others on this forum about it?
Thank you so much for the help!

[Diah]

Re: Toshiba 46L5200U flash logo on screen when turn on

take look on yours Photo No 3.
from left to right ------>
o o o o o = 4 Groups with 1 GND
94 V. Max
SLED date... S46 = for 46 panel Size
7030L = Led Type / size
64 = No of LEDs on Strips

-----------------------------
64 / 4 = 16 LEDs each Group 16 x 6V = 96V close to 94V. Max.

[vinceroger69]

Re: Toshiba 46L5200U flash logo on screen when turn on

take look on yours Photo No 3.
from left to right ------>
o o o o o = 4 Groups with 1 GND
94 V. Max
SLED date... S46 = for 46 panel Size
7030L = Led Type / size
64 = No of LEDs on Strips

-----------------------------
64 / 4 = 16 LEDs each Group 16 x 6V = 96V close to 94V. Max.

Thankyou some good information.