No power, power light just blinks on Sharp Aquos LC-37D44U LCD Televsion

[SurrealMustard]

I'm working on this Sharp Aquos LC-37D44U LCD Televsion and am having problems getting it to start up. When power is first applied, the power light just blinks and never stops (the power button is unresponsive at this time too). Following the advice found in another thread on the board, I tried the "input and volume down" trick, which will allow the set to power on and operate properly for about 2 seconds before the backlight cuts off (the rest of the set follows suit a few moments later).

Based on what was posted in that other thread, this sounds like a bad backlight or inverter problem. Does that sound like a feasible diagnosis? Would a new inverter board be a good place to start the repair process?

[budm]

Re: No power, power light just blinks on Sharp Aquos LC-37D44U LCD Televsion

You can check the Inverter transformer high Voltage winding resistance first.

[SurrealMustard]

Wounded winding

You can check the Inverter transformer high Voltage winding resistance first.

Would that be those five black modules on the inverter? Would they test the same as in this write-up?

[SurrealMustard]

Still no good

Well, I tried replacing the inverter with a working used model that I purchased online, but the backlight still won't stay on for more than a couple seconds after power-up. Could this mean that the panel is bad?

[budm]

Re: Still no good

Well, I tried replacing the inverter with a working used model that I purchased online, but the backlight still won't stay on for more than a couple seconds after power-up. Could this mean that the panel is bad?

That means you may may have bad lamp/s or bad connections to the lamps.

[SurrealMustard]

lamps question

That means you may may have bad lamp/s or bad connections to the lamps.

Can those be replaced independently of the panel?

[budm]

Re: No power, power light just blinks on Sharp Aquos LC-37D44U LCD Televsion

Each lamp can be replaced, you will have to match the dimensions, worth it? I am not sure. You can get the LCD panel model number and then look up the spec sheet of the panel.
http://www.ccflwarehouse.com/

[SurrealMustard]

C7558

Each lamp can be replaced, you will have to match the dimensions, worth it? I am not sure. You can get the LCD panel model number and then look up the spec sheet of the panel.
http://www.ccflwarehouse.com/

I see. Now, I read some threads and watched some videos for similar models that say that you can bridge the capacitor at C7558 to bypass the shutdown so that you can verify the problem. Would this be something worth trying? If so, is the correct capacitor to bridge always C7558 or is it different from model to model?

[budm]

Re: C7558

I see. Now, I read some threads and watched some videos for similar models that say that you can bridge the capacitor at C7558 to bypass the shutdown so that you can verify the problem. Would this be something worth trying? If so, is the correct capacitor to bridge always C7558 or is it different from model to model?

That is if it uses the same IC for the backlights controller, you need to look up the spec sheet of the IC.

[SurrealMustard]

Ic

That is if it uses the same IC for the backlights controller, you need to look up the spec sheet of the IC.

The author in the video I watched was actually kind enough to point out which IC was close to the capacitor and it was indeed the exact same one. Based on this, it would seem like it should work. I think I'll give it a try. What do you think?

[SurrealMustard]

Oops

Hmmm... Apparently there's a reason for that safety circuit. When I turned the set on with the capacitor bypassed, it stayed on, but smoke started pouring out by the corners after a short time. Is that a sign of a bad lamp?

[budm]

Re: No power, power light just blinks on Sharp Aquos LC-37D44U LCD Televsion

When you have lamp that when startup firing Voltage is applied to the lamp but the lamp does not conduct and stay on then the protection circuit will kick in, this happen in the 3 seconds window and that is that timing cap is for, so when the safety is bypass, the high Voltage will keep on feeding the lamp since the lamp is not conducting so the high Voltage will find another path for the current to flow through.

[SurrealMustard]

lamps

When you have lamp that when startup firing Voltage is applied to the lamp but the lamp does not conduct and stay on then the protection circuit will kick in, this happen in the 3 seconds window and that is that timing cap is for, so when the safety is bypass, the high Voltage will keep on feeding the lamp since the lamp is not conducting so the high Voltage will find another path for the current to flow through.

I see. Now assuming our little cookout didn't damage anything else, how would I go about finding the right lamp so that we can decide if this is worth repair or not? The sticker on top identifies the panel as an "R1LK370T3GW20Z" or possibly a "LK370T3GW20Z", but I can't find any specification sheets or anything signifying what type of lamp it would take.

[budm]

Re: No power, power light just blinks on Sharp Aquos LC-37D44U LCD Televsion

You will have to take the panel apart and measure the length and Dia, then go to http://www.ccflwarehouse.com/
BTW, hopefully the inverter transformer and the lamp's connection are not damaged, you should look to see what are damaged at this point. You can also inspect other lamps to see what condition they are in.

[SurrealMustard]

lamp

You will have to take the panel apart and measure the length and Dia, then go to http://www.ccflwarehouse.com/
BTW, hopefully the inverter transformer and the lamp's connection are not damaged, you should look to see what are damaged at this point. You can also inspect other lamps to see what condition they are in.

I'm guessing I'll have to take a look inside. Is getting into the panel fairly straightforward?

[budm]

Re: No power, power light just blinks on Sharp Aquos LC-37D44U LCD Televsion

Just have to be real careful and make sure to remember how all the sheets are stacked on top of each other.

[SurrealMustard]

Sounds in-depth

Just have to be real careful and make sure to remember how all the sheets are stacked on top of each other.

Wow, that sounds pretty in-depth. I'm guessing the whole panel has to come out of the set to do that then?

[SurrealMustard]

Bittersweet ending

Ended up selling this one instead of venturing in to replacing the backlights because there wasn't much information available. Maybe next time.