Toshiba 55HT1U - Backlight inverter board failure fix?

[mu2]

Hi,

I just repaired a Toshiba 55HT1U where the backlight inverter failed. I replaced the entire set of four boards (two master and two slaves) which included the jumpers between the boards. I replaced a Rev.6 set with another Rev.6 set.
The jumper between the slave inverter boards was badly burned and I wonder how long this new set will last.
Does anyone know what the cause of this failure might be? It seems to be a pretty common problem. Is there a modification of some sort or a service bulletin from Toshiba?
I would really hate to have the problem occur again if there is a fix out there!

Thanks,
Mike

[tom66]

Re: Toshiba 55HT1U - Backlight inverter board failure fix?

The cause of burned connectors is typically intermittent/loose connectors causing high resistance heating. To avoid this, make sure the connector is fully seated.

[Louis82]

Re: Toshiba 55HT1U - Backlight inverter board failure fix?

Hello Guys,
I have the same problem as mu2. Slave Inv. Boards appeared all burned. I replaced all 4 inverter boards (master and slaves). Tv worked great for 5 minutes. I turned off so i could put back cover on and now picture doesn't come on anymore. Screen flashes like if picture or lamps are about to turn on but nothing. Still can see with a flash light the menu or display in the back.

Any idea or suggestion for me to try next ? Are Circuit boards defective or is it a panel/screen problem.

I will appreciate your help.

Thank you.

[tom66]

Re: Toshiba 55HT1U - Backlight inverter board failure fix?

Did you fully clean off all carbonisation and make sure the connector is properly connected? You should probably use heavy duty wire in place of connectors.

[Louis82]

Re: Toshiba 55HT1U - Backlight inverter board failure fix?

Thank you the reply Tom66. Yes i did reseat those connector specifically and still the same.

[tom66]

Re: Toshiba 55HT1U - Backlight inverter board failure fix?

How bad is the damage? Picture?

[Louis82]

Re: Toshiba 55HT1U - Backlight inverter board failure fix?

The 14 pin connector that connects the slave 1 and 2 were fried. Would love to send pics but i already got rid of those circuit boards. Im stuck with the new boards and not sure if i should return them as defective or if panel is bad. Thank you for replying. How likely could be that panel or inside lamp is defective and probably at this point damaged my inv. boards.

[tom66]

Re: Toshiba 55HT1U - Backlight inverter board failure fix?

It would help to try with the old boards, but guess they are gone. More likely inverter than bulb if it's sudden, but with a two-sec to black fault, could be bulbs. All fuses on inverters OK?

[Louis82]

Re: Toshiba 55HT1U - Backlight inverter board failure fix?

Yes, It flashes for a sec then black , then flash again for a sec and finally goes and stay black again. Fuses are ok. With old boards i remember that i couldn't even see the menu in the back with flash light. I also would like to mention that when i had those 5 min of "good" picture, it wasn't that bright as a tv in normal working condition.

[tom66]

Re: Toshiba 55HT1U - Backlight inverter board failure fix?

To see if inverters are working, my favourite trick is to use a neon bulb like this:
http://i01.i.aliimg.com/wsphoto/v0/3...t-b-bulb-b.jpg

and put it near the inverter transformers/outputs. I do this for all of them. Working transformers/outputs will make the neon glow quite strongly. If you find the neon does not light on some areas, there's a fault there.

[Louis82]

Re: Toshiba 55HT1U - Backlight inverter board failure fix?

Thanks for the tip tom66. I tried today and transformers test to be good. I'm done. This is a defective panel/screen. I appreciated the help.

[sirjoseph81]

Re: Toshiba 55HT1U - Backlight inverter board failure fix?

mu2. Where did you find your parts? I am having to do the same repair

[mu2]

Re: Toshiba 55HT1U - Backlight inverter board failure fix?

Hi,

I got lucky and found a good price on Ebay for the boards - but that was almost a year ago.
I think that Shop Jimmy has or had the jumper assemblies only.
The television is still working but the owner doesn't use it very often as it is in a guest bedroom. If this was the main television I just wonder if the replacement boards would still be working?

Mike

[stj]

Re: Toshiba 55HT1U - Backlight inverter board failure fix?

when a socket burns up,
it means the contacts both on the board AND ON THE CABLE are screwed.

[Ltank]

Re: Toshiba 55HT1U - Backlight inverter board failure fix?

Boards have bad design. They use both P and N channel mosfets.
The Drains are common to each other. That ties to one side of making the ac to the high voltage transformers. If you examine the circuit you will see.

[Ltank]

Re: Toshiba 55HT1U - Backlight inverter board failure fix?

I had a part 2 board fry the connectors and cable. The slave shorted and draws high current smoking it.

[Johnny]

Re: Toshiba 55HT1U - Backlight inverter board failure fix?

I was able to repair burned inverter boards on the Toshiba 55ht1u See my post on Youtube under CYJO2009

[Shane711]

Re: Toshiba 55HT1U - Backlight inverter board failure fix?

I was able to repair burned inverter boards on the Toshiba 55ht1u See my post on YouTube under CYJO2009

Johnny, I found your YouTube page. I left this same comment.

I say don't use a wire harness at all, just remove the harness and add thicker wires soldering them right to the board. Avoid loose connections by just soldering wires to the board. That's what I'm going to do.