Help Plz. My TV has audio but no picture (Sharp Aquos LC-70C6600U)

[SkyBird]

Good Night,

What is wrong with my TV?

The symptoms before the picture went:
- Would restart randomly
- Started frequently freezing up while watching Netflix or using the USB drive
- WiFi stopped working

After picture went:
- a flash of light when turned on but no image during flash
- no backlight
- No image using the flashlight test
- audio is fine

After changing the main unit/board
- same as above except now I see an image with full color for a moment when I power on (during the initial flash)

Voltage tests with power on:
1) PNL12V = 0V
2) PNL12V = 0V
3) GND = 0V
4) GND = 0V
5) UR13V = 10.3V
6) UR13V = 6.5V
7) UR13V = 0V
8) UR13V = 0V
9) GND = 28.1V
10) GND = 28V
11) GND = 0V
12) GND = 25.8V

LED1+ = 0.8V (was 163V before replacing the main unit)
LED2+ = 160V (was 159.5V before replacing the main unit)
LED3+ = 168V (was 170V before replacing the main unit)

Can you guys help me solve this?

[R_J]

Re: Help Plz. My TV has audio but no picture (Sharp Aquos LC-70C6600U)

All 3 led voltages come from the same transformer, so if you are missing led 1, check for open C7201 capacitor or bad/open D7224.
You can also check the voltage on D7224 and see if it is 160v
If you don't have a capacitor to replace C7201, exchange C7201 and C7202 and see if you have voltage on led 1

[dick_barton]

Re: Help Plz. My TV has audio but no picture (Sharp Aquos LC-70C6600U)

Good Night,

Voltage tests with power on:
1) PNL12V = 0V
2) PNL12V = 0V
3) GND = 0V
4) GND = 0V
5) UR13V = 10.3V
6) UR13V = 6.5V
7) UR13V = 0V
8) UR13V = 0V
9) GND = 28.1V
10) GND = 28V
11) GND = 0V
12) GND = 25.8V

These readings are not right since GND (ground) is always 0V so I suspect you have your pins incorrectly numbered.

[SkyBird]

Re: Help Plz. My TV has audio but no picture (Sharp Aquos LC-70C6600U)

All 3 led voltages come from the same transformer, so if you are missing led 1, check for open C7201 capacitor or bad/open D7224.
You can also check the voltage on D7224 and see if it is 160v
If you don't have a capacitor to replace C7201, exchange C7201 and C7202 and see if you have voltage on led 1

Hmm, thanks. I didn't see anything visibly wrong with them. Can a voltage test tell me if they are bad/open?

I really don't know much about electronics, lol.

[SkyBird]

Re: Help Plz. My TV has audio but no picture (Sharp Aquos LC-70C6600U)

These readings are not right since GND (ground) is always 0V so I suspect you have your pins incorrectly numbered.

I was thinking the same thing but I don't think any of the pins should be reading higher than 13V either. It's very strange.

[budwich]

Re: Help Plz. My TV has audio but no picture (Sharp Aquos LC-70C6600U)

"I really don't know much about electronics, lol.".... :-)

Then the next question would be what were you using for the "ref point" ie. the black probe?

Anyways, you can check the GRD designations with power unplugged and using the resistance scale on the meter, touch / connect / measure from two of the points... it should read 0 (or buzz as a "short"). Check all the "pairs" of points / gnds... all should be the same. IF not, you might have found part of your problem.

[SkyBird]

Re: Help Plz. My TV has audio but no picture (Sharp Aquos LC-70C6600U)

Okay. I will open up the TV on the weekend and try this.
When you say "measure from two of the points", do you mean any grounded object and the test point?

For the reference point, I had used one of the silver knobs that wasn't on the power board itself. (instructed from a youtube vid)

[R_J]

Re: Help Plz. My TV has audio but no picture (Sharp Aquos LC-70C6600U)

I was going by what you said in post #1 --->
LED1+ = 0.8V (was 163V before replacing the main unit)
LED2+ = 160V (was 159.5V before replacing the main unit)
LED3+ = 168V (was 170V before replacing the main unit)

The voltage on LED1+ = 0.8v but the other two voltages are +160V
Since they are produced by the same transformer, it must be one of the lines FROM the transformer that is not producing LED1+ ( or you measured wrong)

[budm]

Re: Help Plz. My TV has audio but no picture (Sharp Aquos LC-70C6600U)

Good Night,

What is wrong with my TV?

The symptoms before the picture went:
- Would restart randomly
- Started frequently freezing up while watching Netflix or using the USB drive
- WiFi stopped working

After picture went:
- a flash of light when turned on but no image during flash
- no backlight
- No image using the flashlight test
- audio is fine

After changing the main unit/board
- same as above except now I see an image with full color for a moment when I power on (during the initial flash)

Voltage tests with power on:
1) PNL12V = 0V
2) PNL12V = 0V
3) GND = 0V
4) GND = 0V
5) UR13V = 10.3V
6) UR13V = 6.5V
7) UR13V = 0V
8) UR13V = 0V
9) GND = 28.1V
10) GND = 28V
11) GND = 0V
12) GND = 25.8V

LED1+ = 0.8V (was 163V before replacing the main unit)
LED2+ = 160V (was 159.5V before replacing the main unit)
LED3+ = 168V (was 170V before replacing the main unit)

Can you guys help me solve this?

The very least that you can do is to upload good clear pictures of the boards and connectors so we can see what we are dealing with.

[budwich]

Re: Help Plz. My TV has audio but no picture (Sharp Aquos LC-70C6600U)

You should try disconnecting one tcon to panel cable at a time ( 1 out of 4... with power off, then power up) and see what the result is. This may help identify your problem.

[SkyBird]

Re: Help Plz. My TV has audio but no picture (Sharp Aquos LC-70C6600U)

I was going by what you said in post #1 --->
LED1+ = 0.8V (was 163V before replacing the main unit)
LED2+ = 160V (was 159.5V before replacing the main unit)
LED3+ = 168V (was 170V before replacing the main unit)

The voltage on LED1+ = 0.8v but the other two voltages are +160V
Since they are produced by the same transformer, it must be one of the lines FROM the transformer that is not producing LED1+ ( or you measured wrong)

Hmm... ok. Thanks.

And yes, unfortunately it's the correct measurement. I tested it a few times to be sure.

[SkyBird]

Re: Help Plz. My TV has audio but no picture (Sharp Aquos LC-70C6600U)

The very least that you can do is to upload good clear pictures of the boards and connectors so we can see what we are dealing with.

I have the pictures but I don't know how to upload them since the picture insert is asking for html :|

[SkyBird]

Re: Help Plz. My TV has audio but no picture (Sharp Aquos LC-70C6600U)

You should try disconnecting one tcon to panel cable at a time ( 1 out of 4... with power off, then power up) and see what the result is. This may help identify your problem.

Ok, I will try this and let you know the results. Thanks

[R_J]

Re: Help Plz. My TV has audio but no picture (Sharp Aquos LC-70C6600U)

To upload a picture, click on go advanced and click on the paper clip next to the smiley face, then browse to your pictures, then click upload