Sony Bravia T-Con Power Spike and drop?????

[bigtony5858]

Hi all!

I have been diagnosing what is wrong with my Sony bravia KDL-46XBR4 and took the entire t-con board off of the panel to inspect it. I decided to create a solder bridge across the top of the fuse because it appeared that the fuse may be bad. When I did so and hooked it up there was a noticeable change. I took my ohm meter and decided to put the positive side (with it switched to 20 DC) and put it on the back of the t-con fuse. The meter read, 3, 6, 10, 12.2, 1, 3, 5, 10, 12.1, 0 and while it was spiking up and back down I could hear a strange clicking sound on the t-con itself. At every very quiet click the power would drop back to zero or close to it.

I tested the power coming into the UB1 board from the GF1 board and it was a steady 12.4, which I thought was a good sign it is not a power supply issue.

Next I tested the UB1 board and the power on this board was surging in the same way peaking and dropping back down to zero. When I would disconnect the LVDS cables the surging stopped, on both of the boards so I tested the power on the FB1 board and it was steady as well.

Any ideas????? Im thinking t-con is bad, but would like to know before I drop some big bones on it to find out its the UB1 board which is easy to find and cheap.

Thanks!

Tony

[budm]

Re: Sony Bravia T-Con Power Spike and drop?????

Is the fuse open, if it it is, put the meter in DC A mode then put the meter probes on the fuse to check the current draw, it should be around 2~3A DC. I will not do it too long since if there is shorted circuit on the T-CON, you can take out the switched MOSFET on the main board which supplies the 12V to the T-CON.
You can also try disconnecting the ribbon cables between the LCD panel and the T-CON board to see if the voltage will become steady.

[bigtony5858]

Re: Sony Bravia T-Con Power Spike and drop?????

Is the fuse open, if it it is, put the meter in DC A mode then put the meter probes on the fuse to check the current draw, it should be around 2~3A DC. I will not do it too long since if there is shorted circuit on the T-CON, you can take out the switched MOSFET on the main board which supplies the 12V to the T-CON.
You can also try disconnecting the ribbon cables between the LCD panel and the T-CON board to see if the voltage will become steady.

When you say main board are talking about the power supply or the AU board?

Thanks for your help!

[budm]

Re: Sony Bravia T-Con Power Spike and drop?????

The board where the cable from the T-CON is connected to.

[freakaftr8]

Re: Sony Bravia T-Con Power Spike and drop?????

I've run into a ticking tcon board on a samsung un326000 . I replaced it after not finding the cause and all was well.