TCL 55S401LHAA No Power

[Tech06]

This TV was Brought to me in non working condition. There are no power\standby lights on the set at all. Here is what I have done so far.

1. Took back off of the tv and tested that the system was getting AC voltage at the plug.
2. Tested the fuse on the power board.
3. Tested the DC voltage at the Large Capacitor.(170Vdc)
4. Checked for any obvious burn marks bad solder joints.
5. Unplugged various devices from the main board.(Tcon, Wi-fi module,)

I'm not getting any response from the set at all. When I measure voltage between the Main Board and the Power Board I am only seeing between .1-.23 vdc on some of the pins. That seems low to me.

Any Ideas? Thanks in Advance.

[lotas]

Power Supply TCL 01-L14TH4-PWB

[RDC55]

Try posting the actual voltage measurements at the P2 connector on the Power Supply with the TV powered up. You need to label the pins as to nomenclature and pin number - unfortunately TCL seems to like to make it hard and put the pin assignments on the back of the boards.

[Tech06]

Originally Posted by lotas

Power Supply TCL 01-L14TH4-PWB

lotas, Thanks for the schematic. You wouldn't happen to have the entire Service Manual would you?

[Tech06]

Originally Posted by RDC55

Try posting the actual voltage measurements at the P2 connector on the Power Supply with the TV powered up. You need to label the pins as to nomenclature and pin number - unfortunately TCL seems to like to make it hard and put the pin assignments on the back of the boards.

With my meter set on 20vdc. I show no voltages on the P2 connector at all.

[RDC55]

I believe even with the Power Supply disconnected from the Main you should still be making 12VDC. The PFC will be about 170 VDC until the main is connected and then it should be about 390 VDC any time the TV is plugged in.

So I would say time to troubleshoot the Power Supply or find a replacement if it is not making 12 VDC with it disconnected from the Main.

[Tech06]

So to update this. I did end up replacing the power supply a quite a few months back. The power supply was the issue at the time. It lasted less than a year. I now have the set back again this time with a different issue. The unit powers on and I can hear the system click through the menus but, now the backlight is not coming on at all. I thought there may have been a bad safety resistor but, after replacing that I still have no backlight on the set. I think I should just replace the thing at this point.

[neilc6]

TCLs have lots of backlight failures. Only 2 or 3 rows of LEDs on a TV that size. Panel may also be taped down making the replacement more difficult.

[nomoresonys]

guess you were too busy to report back that a new powerboard fixed the tv. PASS.