Scepter X32 LCD TV that cannot power up

[tzantzai]

Hi all. I have Scepter X32 LCD TV that cannot power up. When I press the power knob the pwr LED turns blue but the screen is dark and no sound. Occasionally after 5, 6 power cord disconnects and reties it will power up normally. I measured the voltages on power supply board after power up: 24VDC = 22.6V, 12VDC = 12.4V, 5VDC = 5.3V. When the TV powers up OK: BL_ON = 5.0V. When the TV cannot power up BL_ON = 0V. Any ideas what's wrong? Thanks.

[selldoor]

Re: Scepter X32 LCD TV that cannot power up

Sounds as though you need to replace some caps -I see you have double posted this
-please dont do that - if its not too late go into your other post and edit it to just say"posted in error"
Then please post pictures using manage attachments - good clear ones of the front and backs of you main board and power supply.

First though just try gently heating the boards in situ with a hair dryer BEFORE you switch on and see if it comes on straight away.

[tzantzai]

Re: Scepter X32 LCD TV that cannot power up

Attached are pictures of Power Brd and Controller Brd. The hair dryer didn't help.

[budm]

Re: Scepter X32 LCD TV that cannot power up

"When the TV powers up OK: BL_ON = 5.0V. When the TV cannot power up BL_ON = 0V. Any ideas what’s wrong? Thanks."
So beside losing BL_ON signal when it does not work, do you also lose PS_ON, 24V and 12V also?

[tzantzai]

Re: Scepter X32 LCD TV that cannot power up

No, All voltages 24V(22.6V), 12V(12.4V), 5V(5.3V) and Standby Voltage(5.0V always presented) are coming up after pressing power knob. The only difference is BL_ON(rather labeled BK_ON). When BK_ON=5V the TV power up OK. When BK_ON=0V TV doesn't power up. BK_ON comes from controller board.

[budm]

Re: Scepter X32 LCD TV that cannot power up

Can we see good clear pictures of the power supply, main board, the whole backside of the TV?
If the BL_ON is not present, the TV should still power up OK, it just will not have backlights, and the sound should work since bl_on is for backlights only.
BTW, is there a cable between inverter board and the T-CON board?

[tzantzai]

Re: Scepter X32 LCD TV that cannot power up

Here is the back side of the TV, I posted the pictures of the Power Supply and Controller in Post #3,4
There is no cable between T-CON board and Inverter. There is cable between T-CON and controller.

[tzantzai]

Re: Scepter X32 LCD TV that cannot power up

Does anybody have the el. schematic for this TV: Sceptre-X32?

[budm]

Re: Scepter X32 LCD TV that cannot power up

There are 3-pin Voltage regulators on the main board, you may want to check the Voltages when the TV is working and when the BK_ON is not present.
Di you try heating and cooling the main board to see what happen?
https://www.badcaps.net/forum/showthread.php?t=22231

[tzantzai]

Re: Scepter X32 LCD TV that cannot power up

There are five 1117B regulators. The voltage readings stay unchanged in both conditions working or not working. When not working there is no 12V to T-CON board. I think it's the main controller board that causing the problem.

[budm]

Re: Scepter X32 LCD TV that cannot power up

That 12V for T-CON is fed through a switched MOSFET which is turned on by the processor so at this point it looks like you will need new main board.
The processor sends out these signals to outside boards: PS_ON, BL_ON (INV ON, or BK_ON), DIM; and internally sends the T-CON on to the switched MOSFET on the main board to send the B+ out to the T-CON board.

[selldoor]

Re: Scepter X32 LCD TV that cannot power up

Perhaps try reflowing the mosfet in case it has a bad joint or maybe replace the mosfet?