Sharp LC70LE755U - Intermittent backlight flickering and loss of sound.

[nomoresonys]

Re: Sharp LC70LE755U - Intermittent backlight flickering and loss of sound.

For re-flowing solder joints on powerboard if needed, just grab a 10-15 dollar soldering iron from a local hardware or a big box store, some even come with some solder included.

[dick_barton]

Re: Sharp LC70LE755U - Intermittent backlight flickering and loss of sound.

I would take the voltage readings at the power supply connector PD pins 1 to 24 when the set is working and again when you lose the sound.

Have you checked if audio is still available at the headphone output when you lose the speaker sound.

[TheForgottenKing]

Re: Sharp LC70LE755U - Intermittent backlight flickering and loss of sound.

Unfortunately I was wrong about my statement of the speakers being attached to the power board, they are attached to the main board. I've attached an image of the block diagram.

[TheForgottenKing]

Re: Sharp LC70LE755U - Intermittent backlight flickering and loss of sound.

Remove power board and check solder joints. I can't guarantee the problem is there, but this is one of the first things to try.

Will do this as well. W̶o̶u̶l̶d̶ i̶t̶ b̶e̶ w̶o̶r̶t̶h̶ t̶r̶y̶i̶n̶g̶ t̶o̶ h̶e̶a̶t̶ t̶h̶e̶ b̶o̶a̶r̶d̶ i̶n̶ a̶n̶ o̶v̶e̶n̶ t̶o̶ r̶e̶f̶l̶o̶w̶ t̶h̶e̶ j̶o̶i̶n̶t̶s̶?̶

NO, DO NOT do this to the power supply board!

Will not do this. Pretend I never said that. Is there a particular reason this is a bad idea?

[R_J]

Re: Sharp LC70LE755U - Intermittent backlight flickering and loss of sound.

will do this as well. Would it be worth trying to heat the board in an oven to reflow the joints?

NO, DO NOT do this to the power supply board!

[TheForgottenKing]

Re: Sharp LC70LE755U - Intermittent backlight flickering and loss of sound.

Remove power board and check solder joints. I can't guarantee the problem is there, but this is one of the first things to try.

Will do this as well. Would it be worth trying to heat the board in an oven to reflow the joints?

[alfatv]

Re: Sharp LC70LE755U - Intermittent backlight flickering and loss of sound.

Remove power board and check solder joints. I can't guarantee the problem is there, but this is one of the first things to try.

[TheForgottenKing]

Re: Sharp LC70LE755U - Intermittent backlight flickering and loss of sound.

Some photo's of your circuit boards could prove useful.

Have you taken any power supply voltage measurements.

When the backlights and sound go off does the remote control still work.

With a bright light shone at the screen (at an angle) can you see if the picture still there.

Does the led(s) on the front flash?

I'll disassemble it tomorrow before work, and try to get some up-close pictures. Is there any areas of interest?

I haven't taken any voltage measurements. I'll try to do so but the intermittent style of the problem might make this difficult.

The remote control continues to work, and the TV continues to properly display an image. The backlight and image stays on, it's just a quick flicker and the image continues to work after.

[dick_barton]

Re: Sharp LC70LE755U - Intermittent backlight flickering and loss of sound.

Some photo's of your circuit boards could prove useful.

Have you taken any power supply voltage measurements.

When the backlights and sound go off does the remote control still work.

With a bright light shone at the screen (at an angle) can you see if the picture still there.

Does the led(s) on the front flash?

[TheForgottenKing]

Hello everyone, first time posting here so I hope I'm doing everything right.

I just came into possession of a Sharp Aquos LC70LE755U. It was free for me, so with the stand and power cable I only have $30 in this. As such, I'm trying to repair it for cheap.

It works most of the time perfectly, except for an issue with what I think is the power supply. After anywhere from 10-30 minutes of usage, the screen backlight will flicker briefly, and the sound will completely stop working. The sound doesn't start working until I unplug the TV, wait a few seconds, and plug it back in. In addition, at lower brightnesses, the screen backlight flickers randomly.

From my research I've gleaned that both the backlight and speakers are hooked up directly to the power supply board, and now I'm wondering where to start looking as to repairing it. I'm also trying to get a board for cheap and just swap it in.