how to determine if its a bad main or tcon?

[mattstolte]

I am working on a few sets that the backlight lights up but no picture how can I determine if its a bad main or tcon?

[lookimback]

Re: how to determine if its a bad main or tcon?

I am working on a few sets that the backlight lights up but no picture how can I determine if its a bad main or tcon?

Add panel to that too. No picture can also be caused by a bad panel. I usually begin by disconnecting the ribbon cables which connect the Tcon to the panel address boards. Do one at a time and cycle power. If you get a picture on one side, your main board is good and the problem is likely the panel.

[CapLeaker]

Re: how to determine if its a bad main or tcon?

take a 100Mhz oscilloscope and look at the LVDS signal that goes from the main board to the tcon. Flick the menu button on and off and you should see the signal changing in the oscilloscope.
Sometimes disconnecting one cable at a time from the tcon to the panel wont work. At least it didn't on the last 60" Samsung that I fixed.
Do some research of your TV model number at SJ for instance.
Also check the fuses on the tcon!

[mattstolte]

Re: how to determine if its a bad main or tcon?

i dont have a scope. and what about sets that just have 1 ribbon to panel and screen lights up but no picture how can you determine then if its tcon or main?

[budm]

Re: how to determine if its a bad main or tcon?

You can start by at least checking the DCV feeding the T-CON, then there are 2~3 switching power supplies on the T-CON and regulator ICs which you need to test the Voltages. If some of the Voltages are not present, then disconnect the ribbon cable/s between the T-CON and the panel to see if the Voltages come back. Most of the T-CON boards have test points for testing the Voltages.

https://www.badcaps.net/forum/showpo...&postcount=202

[tom66]

Re: how to determine if its a bad main or tcon?

If all the voltages are good and there is nothing else obviously wrong the only way I know of is to use a scope to check the LVDS signals like CapLeaker says