vizio vw42l hdtv10a no picture/sound

[blmcamp]

Re: vizio vw42l hdtv10a no picture/sound

I completely understand about being busy.
Just so you know, I don't mind replacing any of the boards I just don't want to buy a board if it is something else like the backlights. also I don't know what board is bad so that is why I want to test them so I am sure I am replacing the correct one.
Remember I have already replaces a surface mounted 3a fuse on the main board and the backlights are still not coming on when I turn the power on.
Someone else mentioned changing some other things on the main board a couple of posts ago, if you think the issue is with the main board then maybe I should just get one of those. What do you think?
again thank you for your help

[budm]

Re: vizio vw42l hdtv10a no picture/sound

All I can tell right now after checking the signals from the main board that you have posted, the power-inverter board is getting the correct signals (PS_ON (PFC is working isince you are getting the 380VDC), iNV_ON) from the main board but the backlights still do not come on. As far as trying to find out if the lamps are good or not, that will not be an easy thing to do, you will need to get external high voltage power source to drive each lamp to find out if one or more of them is bad or not.
This is the simplified diagram of the Inverter transformer drive circuit, it looks like the Gate drive transformer is not getting the drive signal for the ICS301 and the circuits around it. This is going to be in depth troubleshooting and SMD component replacement. We will need to look and find out if the ICS301 (LX1692) has any DC voltage between the Ground pin and the VCC pin or not when the TV is turn on.
You can also try forcing on the INV_ON pin by disconnecting that wire from the power supply board first and then use 1K resistor between the INV_ON pin and the 5VSTBY pin to see if you can get the backlights to come on when TV is powered up.

[blmcamp]

Re: vizio vw42l hdtv10a no picture/sound

Wow, that's a lot to take in.
What you said here is correct.

"All I can tell right now after checking the signals from the main board that you have posted, the power-inverter board is getting the correct signals (PS_ON (PFC is working since you are getting the 380VDC), iNV_ON) from the main board but the backlights still do not come on."

I checked the power with a multi-meter at the plug the back lights plug into on the power/inverter board with the power on and there is not any power on either of them.

so, am I correct that it sounds like you feel it may be the Power/inverter board which is bad.
should I just change that and see what happens?

[blmcamp]

Re: vizio vw42l hdtv10a no picture/sound

OK, I found the ICS301. I attached a Picture

you said I will need to look and find out if the ICS301 (LX1692) has any DC voltage between the Ground pin and the VCC pin or not when the TV is turn on.

can you tell me which one is the Ground Pin and which one is the VCC pin.

I noticed there is a Dot, more like an indentation in the lower left hand side of the ICS301, Is that the ground?

[johnboy1313]

Re: vizio vw42l hdtv10a no picture/sound

No, that tells you where pin 1 is.

[blmcamp]

Re: vizio vw42l hdtv10a no picture/sound

Ya know, I think I knew that, don't know why I asked. also I asked before I read the doc Bud attached. it is a detailed guide to the chip. Now I have another problem, I accidentally blew the ceramic fuse right by the power plug on the power board. does anyone know where I can get one of those?