Toshiba 46SV670U

[mike123333]

Hello - I am trying to troubleshoot a friends LCD TV Toshiba 46SV670U ( less than 3 yrs old) which has sound but no video. Originally my freind mentioned that before the video crapped out it got vertical color lines then after that no more video but sound.

The TV will turn on with the bright blue LED and the Toshiba logo lights up but no video. There are no signs of any back light flicker or presence of. I have powered up in a dark room with no success.

The testing I have perfromed so far:

1. Reseating all the cabling and wire harnesseses.
2. Checked out all the voltage on the PS and all check out good ( 5v,12v,24v). I do have the high voltage of 388VDC.
3. I have tested most of the basic compenents fuses and diodes on the PS with no issues.

How do I go about testing the inverter for functionality?

Any input would be greatly appreciated.


Mike

[Mr Bill]

Re: Toshiba 46SV670U

Shine a flashlight on the screen in an extremely dark room. I usually put the flashlight directly on the screen and then hit the volume or menu key. Check the fuses on the inverter board too.

Can you post a picture of the inverter board.

***EDIT****
Is this tv a LED? I'm not finding any inverter boards at shop jimmy.

[Mad_Professor]

Re: Toshiba 46SV670U

Hello - I am trying to troubleshoot a friends LCD TV Toshiba 46SV670U ( less than 3 yrs old) which has sound but no video. Originally my freind mentioned that before the video crapped out it got vertical color lines then after that no more video but sound.

The TV will turn on with the bright blue LED and the Toshiba logo lights up but no video. There are no signs of any back light flicker or presence of. I have powered up in a dark room with no success.

The testing I have perfromed so far:

1. Reseating all the cabling and wire harnesseses.
2. Checked out all the voltage on the PS and all check out good ( 5v,12v,24v). I do have the high voltage of 388VDC.
3. I have tested most of the basic compenents fuses and diodes on the PS with no issues.

How do I go about testing the inverter for functionality?

Any input would be greatly appreciated.


Mike

Sounds like the T-CON board crap out. It has control over the backlight operations and displaying video. If there is a fault in either, no picture.

Shine a flashlight into screen and check for image.

Disconnect T-CON and see if the backlight comes on, it should without the T-CON.

They are usually cheap to replace or repair.

Also did you test the voltage while there was a load?

[mike123333]

Re: Toshiba 46SV670U

it appears this TV uses LED as the backlight from what I can see the dissassembly is a bare.

I did shine light but I cannot see anything even with pressing the vol or menu control.

As for the voltages they were taken whiloe everything was attached and switched on.

How can I check the LED?

[budm]

Re: Toshiba 46SV670U

It depends on how they connect the LEDs, If they are in one string then if one goes open circuits, the string will not light up.
Need to see closed up pictures of the connectors on the power board. Is there another board that is connected to the backlights assembly?
Here are the pictures of Backlit LED setup for 32", it uses 32 LED's in one string fed by 90VDC, so if one goes out the whole string will be dead.
Not sure if your TV uses the Back-lit LED's setup or Edge-lit LED's setup for your TV.
http://s807.photobucket.com/albums/y...2EH4050F%20TV/

[Mr Bill]

Re: Toshiba 46SV670U

Have you checked to see if there are any fuses on the mainboard? I had a sony bravia that had a fuse blown on the mainboard and it had a "no video" stmptom. Have you checked the fuse on the tcon board?

[mike123333]

Re: Toshiba 46SV670U

As for the TCON I checked the fuse.I will have to pull the main board off and see if IO find any issues with fuses.

It looks like there is one long board that runs across the base of the TV which would be for the LED. I can not tell whether its one or 2 boards. I will have to remove it and see now.

Teh photos of the boards I posted is all the boards that are visible. Let me take the TV apart to get to the base boards

[mike123333]

Re: Toshiba 46SV670U

here are the photos of the boards that energize the LEDS,

[mike123333]

Re: Toshiba 46SV670U

pelimanry testing shows all fuses are good on these boards.

[mike123333]

Re: Toshiba 46SV670U

would the 24VDC be the correct voltage for energizing the LED's.. I wil need to test the voltages on these boards..

[tom66]

Re: Toshiba 46SV670U

Possibly a little higher, is the output not labelled on the board?

[selldoor]

Re: Toshiba 46SV670U

Some of the pictures are too blurred for trouble shooting. It would also help if you actually said which fuses you had tested in the format LD Board V2 Fuse F1 = ohms x
so that we know for certain they are ok. I pick that example as I cant see it mentioned.

[mike123333]

Re: Toshiba 46SV670U

I noticed the pictures this morning that were a bit blurred. I will have to take new photos tonight when I get home. The fuses tested about 0.1-0.3 on my fluke meter. The fuses were tested on the boards in #8 above.

[mike123333]

Re: Toshiba 46SV670U

After ripping everything apart I disconnected the main harness that goes back to the LD_Board V2 shown in the photos in post #1 and the back light comes on but still no video. With evetything else attached to this board the back light stays on but no video once I attach the wire harness then the the back light goes out. Can I safely assume that this board is defective I will do some testing.

Where can I purchase this board.. I tried ebay for parts for thsi TV but the only thing I seen was remote controls. Shop Jummy only has PS

[mike123333]

Re: Toshiba 46SV670U

Another test I performed was to disconnect everythign from thsi board but only attached the colred wire harness I mentioned in the previosu post the backlight goes out. Once I disconnect it while its powered up the backlight immediately comes back.

It appears that the wiring from this harness travels through 2 IC chips marked LVX125 which seems to be a CMOS then goes to the main processor.

[Mr Bill]

Re: Toshiba 46SV670U

That board i believe is a dimmer board. I did a search for the tv parts and then a google search for the seperate boards. Here is a link to it. A little pricy. You would think a 3 year old tv would have more parts available.

http://ehservice.ca/parts/index.php?...roduct_id=1105

[mike123333]

Re: Toshiba 46SV670U

Mr. Bill thanks..so thsi is not part of the TCON bopard system? the TCON center board wire harnesses go to this board.

[Mr Bill]

Re: Toshiba 46SV670U

Can you elaborate more on post #14. I want to make sure i'm understanding this. If all wires from the dimmer board (LD_board v2) are disconnected the backlight comes on but when you hook the wire harness the backlight goes out? What wire harness are you reffering too? Does this harness go to the tcon or from the main board?

[mike123333]

Re: Toshiba 46SV670U

The wire harness I am referring to is CN07 the one with the colored wires. the upper left going through IC10 and IC11. If I have only this harness attached to the dimmer board with no other wires the back lights will not come on.

This harness goes directly to the LED inverter boards at the base of the TV.

I hope this carlifies matters for you.

[mike123333]

Re: Toshiba 46SV670U

Also, even if I have all other wiring connected to the board and the CN07 disconnected the back light will turn on. This particular harness seem to be causing the back lights not to come on.