Luxor LUX-22-822-COB stuck in standby

[sordids999]

hello

picked up this tv tonight standby light is stuck on blue light

cant get any voltage readingsoff the power supply

im just wondering if its the built in inverter ? best way to test to see if its working or faulty ?

thanks

[ReeceyBurger123]

Re: Luxor LUX-22-822-COB stuck in standby

To test the inverter check the mosfet for shorts. Also have you forgotten about Vestels ? If you unplug the Mb the Psu will turn on the 12v 5v and 3.3v so give that a try.

[sordids999]

Re: Luxor LUX-22-822-COB stuck in standby

Also have you forgotten about Vestels ? If you unplug the Mb the Psu will turn on the 12v 5v and 3.3v so give that a try.

Already tried that mate no voltages but ill test the mosfets in a bit

cheers

[ReeceyBurger123]

Re: Luxor LUX-22-822-COB stuck in standby

No worries mate

[sordids999]

Re: Luxor LUX-22-822-COB stuck in standby

Strange !
tested mosfets not shorts and now with the psu disconnected from the mb i tested the voltages again and now i have 12v/5v but fluctuating voltages up and down

[ReeceyBurger123]

Re: Luxor LUX-22-822-COB stuck in standby

Sounds like a bad start up/feedback cap to me. Try heating the Psu maybe ?

[dick_barton]

Re: Luxor LUX-22-822-COB stuck in standby

The schematic appears to show that you need the STBY_ON/OFF if that is the correct schematic for you power supply'

[budm]

Re: Luxor LUX-22-822-COB stuck in standby

This is an always on power supply so is the +5STBY and the 14.5V steady?
The other Voltages are fed from the +5STBY and the 14.5 to feed the switches which are turned on when it get the PS-ON signal to give you the switched +5V, +12V, +33VDC.

[ReeceyBurger123]

Re: Luxor LUX-22-822-COB stuck in standby

For Vestel boards they do not need the Pson signal, the Pson goes high with mobo unpluged with it plugged in and the set in Pson it is low and the Psu turns off the other rails.

[ReeceyBurger123]

Re: Luxor LUX-22-822-COB stuck in standby

This is the same for all Vestel boards including this one, I might make a video to prove it if I have to lol

[sordids999]

Re: Luxor LUX-22-822-COB stuck in standby

with psu disconnected and reading of PL803 12/5 volts fluctuating and no 33 volt present

[ReeceyBurger123]

Re: Luxor LUX-22-822-COB stuck in standby

33v goes straight to the inverter I think on these so check what the mosfets are getting.

[dick_barton]

Re: Luxor LUX-22-822-COB stuck in standby

The 33V is derived from the +12V supply.

[budm]

Re: Luxor LUX-22-822-COB stuck in standby

This Vestel uses ACTIVE LOW, when STBY_ON/OFF is high the switches are turned off, when when it is LOW the switches are turned on, when the PS-ON of the main board is HIGH to keep the power supply OFF by biasing on the PS-ON line controlled Transistors (Q802, 806, 871, see page 1) on the power supply board to keep the switched power supplies from coming on, so when you disconnect the cable from the main board the PS-ON controlled switched Transistors are turned off due to no biasing which then allow the switched power sections to come on. So it still requires PS-ON which in this case the ACTIVE LOW PS-ON.
The inverter circuit uses 14.5V (Always on 14.5V, feeding the fuse F101 and then get relabeled as 12V, see page 2) for running the inverter drive and output circuits.
The 33V is used for tuner not for the inverter circuit, it is high Voltage (33V) and very low current as you can see from the diagram on how the 33V is generated, the Varactor Diode in the Tuner does not need much current to run.
So +5stby and the 14.5VDC are steady?

[sordids999]

Re: Luxor LUX-22-822-COB stuck in standby

So could it be the main board at fault ?

[ReeceyBurger123]

Re: Luxor LUX-22-822-COB stuck in standby

I think something is wrong some where, just to test I have the same Psu pluged it into mains woth no mobo and got all voltages. I think your Psu is bad tbh. Have you tried heating it ?

[budm]

Re: Luxor LUX-22-822-COB stuck in standby

I think something is wrong some where, just to test I have the same Psu pluged it into mains woth no mobo and got all voltages. I think your Psu is bad tbh. Have you tried heating it ?

You should have all the Voltages since it is ACTIVE LOW so when it is not connected to the main board the power supply does not see the HIGH (from main board) at the STBY_ON/OFF Pin to keep the power supply in OFF STAGE, you can look at the SCH on how it functions.
Most other power supplies use active HIGH for turning ON.

[ReeceyBurger123]

Re: Luxor LUX-22-822-COB stuck in standby

Ahh right sorry misread what you put bud. So the Psu is at fault here.

[budm]

Re: Luxor LUX-22-822-COB stuck in standby

So basically at this point when he does not have the power supply board connected to the main board, all the Voltages should be present.

[ReeceyBurger123]

Re: Luxor LUX-22-822-COB stuck in standby

Yes but he said they fluctuate, these things run hot as well for smaller units so im thinking worn out cap for the feedback or the output.