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Louie
Louie, Technician
Category: TV
Satisfied Customers: 2557
Experience:  25+ yrs. experience in the field and 5+ yrs. online, down to component level.
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I have a toshiba LED tv with a dark screen. The front led

Customer Question

I have a toshiba LED tv with a dark screen. The front led stays green all the time, but no sound or picture. I also can't turn the tv off with the remote. I have to unplug it to power it off.

Submitted: 1 year ago.
Category: TV
Expert:  Louie replied 1 year ago.
Hi again Mike and welcome back to JustAnswer,

Thank you for the new question and your patience. Should you still need assistance for information purposes only...


Initially, have you tried turning the Toshiba On/Off with P803 disconnected ?
Customer: replied 1 year ago.

Ok I tried with P803 disconnected and it still doest do anything. The front LED doesn't flash when I press any button on the remote.

Expert:  Louie replied 1 year ago.
Based on the described symptom and the no-change even with P803 disconnected, then the main board would be highly suspect.

What is the board number of the main board please?
Customer: replied 1 year ago.

ok I found something. SCR1, part number BT169DH, is measuring short from pin 1 to pin 3. The data sheet shows pin 1 being anode and pin 3 being cathode.

Expert:  Louie replied 1 year ago.
Nice find. This SCR serves as a switch.

Would you attempt to replace SCR1 or the whole board?
Customer: replied 1 year ago.

I removed the part and it measures fine out of circuit. When measuring from anode to cathode with part removed it still measures short. Since I can't find a schematic it will be hard to diagnose the part. There is a transformer next to it, can they short out?

Expert:  Louie replied 1 year ago.
Yes but unlikely that this transformer would have shorted. If so, there would be physical sign(s). Chances are that the SCR is tied in parallel to a transformer's winding hence the 0Ω initial reading.

The reason that a part of nor the whole power supply board was not considered a primary suspect is based on "...tested the voltages and they are all there..."

On the otherhand, the reasons that the main board was suspected are:
  • power LED stays green - main board is locked in a mode/function;
  • • can't turn the tv off with the remote - hence CPU/logic circuit is not functioning;
  • 0v on BLON - which is sent by the main board when turning On.

What is the board number of the main board please?
Customer: replied 1 year ago.

I found the main board on here, but it is sold out.

https://www.shopjimmy.com/toshiba-75024013-main-board-for-55sl412u.htm

Expert:  Louie replied 1 year ago.
Unfortunately, it is also out-of-stock with almost all the other online sellers.

Please post back how you would want to approach this and/or should additional information be needed.

Customer: replied 1 year ago.

Not much I can do but wait until a board is available.

Expert:  Louie replied 1 year ago.
I understand. Please post back with an update when able. Cheers.