Sceptre X405BV-FHD3 No power Won't turn on

[budm]

Re: Sceptre X405BV-FHD3 No power Won't turn on

The 24V connector can be disconnected so try that first.

[p1668]

Re: Sceptre X405BV-FHD3 No power Won't turn on

I unplugged the +5V standby and plugged all the cables into the main board and the power board and the voltages did not drop.

The voltages only drop when I have the +5V standby cable plus all the other cables going to the main board.

Does that mean my power supply board is good?

[budm]

Re: Sceptre X405BV-FHD3 No power Won't turn on

You need to have the STB5V connected, but remove the switched 5V.
When you disconnected the STBY5V then the main board will not get power to run so it cannot send the PS-ON signal to turn on the Switched 5v, the switched 12V, or the Switched 24V. So basically there is no load on the power supply when you disconnected the STBY 5V.
What happen to my request on post 21?
You can test the 5VSTBY by using dummy load resistors.

[p1668]

Re: Sceptre X405BV-FHD3 No power Won't turn on

I tested removing each wire and I am measuring the voltages at the diodes; D23 and D10.

Without the main board plugged in, D23 reads +5V and D10 +24V.

When the wires; switched +5v, switched +12v, and switched +24v, are disconnected (one at a time), D23 measurement fluctuate between +1.5v to +1.8v and D10 measurement fluctuates between +8.8v to +5.3v.

[budm]

Re: Sceptre X405BV-FHD3 No power Won't turn on

I tested removing each wire and I am measuring the voltages at the diodes; D23 and D10.

Without the main board plugged in, D23 reads +5V and D10 +24V.

When the wires; switched +5v, switched +12v, and switched +24v, are disconnected (one at a time), D23 measurement fluctuate between +1.5v to +1.8v and D10 measurement fluctuates between +8.8v to +5.3v.

OK, so with all those wires for the three switched supplies are disconnected but the STBY 5 is still connected to the main board then those Voltages readings become unstable. So to find out if the main board is drawing too much current or the power supply is just weak, you need to load down the STBY using resistors to see if it still drops down. You said you already replaced all the caps, I hope it is not the new caps problem, especially those 2 small startup/running caps in the primary side.

[budm]

Re: Sceptre X405BV-FHD3 No power Won't turn on

I tested removing each wire and I am measuring the voltages at the diodes; D23 and D10.

Without the main board plugged in, D23 reads +5V and D10 +24V.

When the wires; switched +5v, switched +12v, and switched +24v, are disconnected (one at a time), D23 measurement fluctuate between +1.5v to +1.8v and D10 measurement fluctuates between +8.8v to +5.3v.

OK, so with all those wires for the three switched supplies are disconnected one at a time but the STBY 5 is still connected to the main board then those Voltages readings become unstable. So to find out if the main board is drawing too much current or the power supply is just weak, you need to load down the STBY using resistors to see if it still drops down. You said you already replaced all the caps, I hope it is not the new caps problem, especially those 2 small startup/running caps in the primary side.

[p1668]

Re: Sceptre X405BV-FHD3 No power Won't turn on

It's possible the C63 50v 10uF capacitor doesn't have a secure solder joint.
That was one of the first one I re-soldered and I burned the board.
I will try and re-solder it again and hopefully I won't cause any more damages.

I tested continuity on one of the leg to the next trace and I had to give a bit of force to get a beep on my DMM.

[p1668]

Re: Sceptre X405BV-FHD3 No power Won't turn on

Any other ideas? Please help.

[ellisol]

Re: Sceptre X405BV-FHD3 No power Won't turn on

I read with interest this thread. I also have a Sceptre of a similar model I am hoping to get some troubleshooting advise on.

I will create a new thread once I am approved.

Thanks, ellisol from Iowa

[nomoresonys]

Re: Sceptre X405BV-FHD3 No power Won't turn on

Test all pins on connector from mainboard to powerbard on powerboard side, all board connected. Test in standby/plugged in but off, then apply power report both conditions, example: pin 1 bl-on=0 volts standby and 3.3 powered on, report results for every pin, this is where most troubleshooting starts, example of testing below in my signature.