Insignia NS-LCD42HD-09 No Picture, No Sound W/ Voltages

[WumpusRX]

The TV was turned on being used for my computer. The screen went completely blank. No picture no sound. The blue LED stayed on steady.

I took the back of the TV off and did a thorough look over of the connections and boards. Nothing looked unusual, out of place, or broken.

I took some voltage readings from the supply board connectors. They are as follows.

5V - 5.01
5V - 5.01
PSON - 3.473
24V - 24.34
24V - 24.34
GND - 0
GND - 0
GND - 0
12V - 12
12V - 12
DIM - 3.216
ON/OFF - 3.318

Blank
Blank
Blank
GND - 0
GND - 0
GND - 0
GND - 0
GND - 0
24V - 24.34
24V - 24.34
24V - 24.34
24V - 24.34
24V - 24.34

DIM - 3.216
ON/OFF - 3.318
ENABLE - 2.539
next 5 are GND and are all 0 Volts
next 5 are all 24 V and are all 24.36 V

5V - 5
5V - 5
PS - 3.471
24V - 24.33
24V - 24.33
GND - 0
GND - 0
GND - 0
12V - 12
12V - 12
ON/OFF - 3.317
DIM - 3.215

I'm stumped.....

[budm]

Re: Insignia NS-LCD42HD-09 No Picture, No Sound W/ Voltages

You have all correct signals, but do you see any glow on the screen at all? We need to find out if the backlights are on but no pictures, or backlights are not on. Pictures of the boards?

[WumpusRX]

Re: Insignia NS-LCD42HD-09 No Picture, No Sound W/ Voltages

I can get pics of the boards when I get home today. I notice when I turn the TV on there is a brief flash of white light from the screen and then nothing. I'll take some more readings on the other connectors as well.

Any other suggestions for diagnostics would be awesome as well.

Thank you for the reply budm.

[budm]

Re: Insignia NS-LCD42HD-09 No Picture, No Sound W/ Voltages

I think you have inverter or lamps problem. That is more like 2-second to black problem.
Will wait for pictures so I can tell you the test points to test.

[WumpusRX]

Re: Insignia NS-LCD42HD-09 No Picture, No Sound W/ Voltages

Here are some pics. If you need something more detailed let me know.

[tom66]

Re: Insignia NS-LCD42HD-09 No Picture, No Sound W/ Voltages

You have CMO inverter. There is a fuse marked 1A/76V usually. Check this fuse is not blown.

[WumpusRX]

Re: Insignia NS-LCD42HD-09 No Picture, No Sound W/ Voltages

Found one that read 0.75A/76V. Checked the resistance. 000.1 Ohm.


Here is a crappy cell picture I took.

[tom66]

Re: Insignia NS-LCD42HD-09 No Picture, No Sound W/ Voltages

OK, do you see any other fuses? Are any of these blown?

[WumpusRX]

Re: Insignia NS-LCD42HD-09 No Picture, No Sound W/ Voltages

The other fuses on the inverter board are reading 0 Ohms F401 on my main (logic) board is reading .9 Ohms.

[tom66]

Re: Insignia NS-LCD42HD-09 No Picture, No Sound W/ Voltages

OK, do you have 24V at both ends of each fuse on the inverter?

[WumpusRX]

Re: Insignia NS-LCD42HD-09 No Picture, No Sound W/ Voltages

No....unless I'm measuring the wrong component.

[tom66]

Re: Insignia NS-LCD42HD-09 No Picture, No Sound W/ Voltages

What component are you measuring? A picture would help.

[WumpusRX]

Re: Insignia NS-LCD42HD-09 No Picture, No Sound W/ Voltages

These jammies circled in red.

[budm]

Re: Insignia NS-LCD42HD-09 No Picture, No Sound W/ Voltages

There is a white flat ribbon cable the goes from the inverter board to the T-CON board connector CON1, disconnect that cable to see if the backlights will come on. This TV has dimming control for contrast enhancement.
By the way, fuses on both inverters are good and getting 24vdc on both ends of the fuses?

[WumpusRX]

Re: Insignia NS-LCD42HD-09 No Picture, No Sound W/ Voltages

budm,

I'm going to check everything again because I may be mistaken about the voltages. The continuity check was ok but I wasn't seeing any voltage through the fuses. I will also try to upload a video of what the screen is actually doing. I will also do what you suggested with the ribbon cable. When you say both inverters you mean both the Master and Slave Boards?

Thank you for being patient with me. I am total newb when it comes to electronic hardware. I'm learning things though.

Also, would a bad inverter or T-CON account for my loss of sound as well? I assumed everything went through the Main Board where all of the peripheral connections are.

[truep]

Re: Insignia NS-LCD42HD-09 No Picture, No Sound W/ Voltages

How are you measuring the voltage "through the fuses" Check both sides to chassis ground.

[WumpusRX]

Re: Insignia NS-LCD42HD-09 No Picture, No Sound W/ Voltages

Yeah I didn't have a good ground when I was checking the fuses. Brain fart.

[WumpusRX]

Re: Insignia NS-LCD42HD-09 No Picture, No Sound W/ Voltages

HOKAY!! All of the fuses on the inverter boards are getting 24VDC on both sides. Good.

budm, I disconnected the white ribbon cable from the CON1 connector and the back light DID come on!

[WumpusRX]

Re: Insignia NS-LCD42HD-09 No Picture, No Sound W/ Voltages

What does this all mean?

[tom66]

Re: Insignia NS-LCD42HD-09 No Picture, No Sound W/ Voltages

The white ribbon cable is the inverter sync cable from the t-con, so most likely you have a defective t-con board keeping the inverter from lighting up.