pins for turn on fsp123-3f01 power board

[spantor]

ok
how many volts when turning on the TV on S2001 between pin1 and pin4

there is no voltage. but there is voltage between positive pin and chassis. there is 190v. negative pin does not close the circuit

[kasfamily]

then you need to measure the voltages at all pin S2000 when turning on the TV

[spantor]

then you need to measure the voltages at all pin S2000 when turning on the TV

[spantor]

?

[spantor]

?

apologies I think VAC voltage I have measured with continuous voltage. I will measure again

[kasfamily]

There is -5.31voltage between pin bl and gnd when I turn on the TV. Then the voltage disappears definitively at the end of the cycle of the two flashes of the standby LED

Why on S2000 pin BL=0, to turn on the backlight there should be about +5 volts

[spantor]

Why on S2000 pin BL=0, to turn on the backlight there should be about +5 volts

I can confirm that between pin bl and pin gnd there is no voltage when turning on the tv.
Pins 110vac and 50vac should be measured in alternating current? I thought that VAC refers to alternating voltage current

[kasfamily]

yes-Pins 110vac and 50vac should be measured in alternating current.
If 5 volts do not appear on pin BL, then there is a problem on the motherboard.
to check the operation of the backlight inverter, connect pin 5v with pin BL via a resistor with a nominal value of about 1 kOhm

[spantor]

I think I can rule out PB. The easiest thing will be to buy a used MB and wait for luck. Thank you for all your patience and knowledge. If I can help you with anything, don't hesitate to ask me.

[kasfamily]

Ok.
Check the voltage on the PFC capacitor in the power supply - it should be about 400 volts.
Check all voltages DC/DC on the motherboard.