Septre x42 lcd tv wont come on i checked all voltage on power supply and they seems to be correct

HI, I'm not familiar with this brand set but in most cases, you can't replace a main board from another size set and have it work. I'd get the right board and see if that fixes it. I'd say the power supply voltages are ok, anything within 10% of rated should be ok, but the voltage to the tcon doesn't sound right, again a main board issue.

While you checked the condensers, did you look for faulty connections? places where the solder has a little crack?
And did you check visually, or did you check electronically? In a power supply lots of things can go wrong. More than alone a capacitor with a rounded head.

great to know whats wrong with it

The most likely issue is your power supply is failing. Most likely issue that would cause this problem is bad capacitors on the power supply.
What happens in the above situation is:
After the Tv has been off for some time the electronics and capacitors are cool and supply the correct voltage so the TV turns on.
After using the TV the electronics heat up and the material in the capacitors expands causing the power supply to supply incorrect voltage. With the TV the power is flowing and is close enough to the correct values for the TV to stay on, after being shut off the TV will not turn back on because correct voltage is not present until the components cool down and the voltage at power on no longer engages the protection circuit.

Info on checking and testing power supply's

Info on finding and repairing bad. Damaged, leaking or swollen capacitors

Hello, from my experience in this type of TV, and by your description, then it seems that the cause is power supply failure. To verify this you can perform several tests while the problem occurs, you have to check the height and stability of the 5V voltage. If not valid then the fault lies in the power supply. If the voltage is proper Check the voltageof the main panel replay 5V to the power supply, which should, cause additional voltage of 12V and 24V to appear. If proper circular tension, and the voltage of 12 and 24 is not out, then the problem stems from the power supply. if improperly circular tension, or if all the tensions I mentioned are in this order, properly, then the problem probably stems from the main boared.

This is a common problem with lcd panel tv's. There is a problem with your power supply. Here are the steps you need to take.
1. Lay the tv face down on a cushioned table. Make sure the table is large enough to support the entire tv, You don't want to damage the panel.
2. Remove all the screws securing the back of the tv to the front.
3. Remove the back
4. Check the power supply pcb for puffed capacitors. If they are puffed, they need to be replaced.
5. Remove all connectors and screws from power supply pcb. This is the board where the power cord attaches.
6. Replace capacitors with equal or slightly greater valued capacitors. The values are marked on the capacitors in mfd and voltage.
7. You wil need a soldering iron to remove and replace them
8. Install the power supply pcb back into the tv and replace the connectors
9. Connect the power cord into the back of the tv and turn on.
10. Check to see if backlight comes on.
11. If it does, press menu button and lift tv up to see if you have an onscreen display. If you do the repair is complete.

If you don't you need to take a digital multimeter and check the voltage ouput from the connectors of the power supply pcb. Connect black lead of your meter to chassis ground and use the red lead and touch each individual pin to see if you have the correct voltage. The voltage levels are printed on the power supply pcb. If they are non existent, then you need to replace the power supply.
You said that you have no power light indicator led on the front panel at all. This tells me you have no standby voltage. Good luck and let me know how you make out

open it up check the power supply for busted/swollen or leaking caps if it has some change them out with new caps with same uf and voltages (although you cna up the voltage a little) - check the voltages coming from the power supply if the tv will stay on long enough to do so - if not order a power supply

thanks,
michael

I have a sceptre tv x42 I lost my cord don't no where to buy another one

The problem can be bad backlight inverter board or it is not getting the 24vdc from the power supply. Look inside to see if it has bad caps with bulging tops. Also check the power supply output voltages, you should have 5vdc, 12vdc, and 24vdc.
Parts: http://www.shopjimmy.com/catalogsearch/result/index/?q=Sceptre+X42GV-Naga&stock=all

It seems your "power regulator" a small unit inside tv device has damaged due to wrong power supply. In this case usually the power capacitor burns and few other electronic components like triodes. Get the help of a electronic chip technician to replace the damaged components.

Hope it works.