Forcing power supply on by jumpering PSON.

[JonathanAnon]

Just looking for general advice is on this... I have a couple of LCD TVs at the moment that I suspect have main board problems... so I would like to unplug the main board and force the power supply on...

Is it generally the case that I can jumper (with 100ohm resistor) PSON to ground, and jumper BLON to ground.. And this should turn the power on and switch the backlight on... Or is this very specific to each particular power supply and I need to work out on the specific PS schematic how to force it to power on?

[selldoor]

Re: Forcing power supply on by jumpering PSON.

Hi Not always the case and not usually those pins and not 100ohm but apart from that yes

Usual if the trigger is low to high then you jumper 5v standby to pson and blon.using 0.5 to 1 kohm resistor. Maybe the dim as well.

Sometimes the trigger is high to low in which case you have to ground the voltage
on the pson and cut the original wire in such a way that it can be re joined.

Pretty sure that is the way of it.

[stj]

Re: Forcing power supply on by jumpering PSON.

i had one where you float the pins to turn it all on and it had pulldown resistors on the logic board.
so to test the psu/invertor you just needed to unplug the link cable.

too bad they dont all do that!

[shelby5041]

Re: Forcing power supply on by jumpering PSON.

hi does anyone know if i can just run a wire from 5v standby and jumper to pson to get power supply to power on? without a resistor? just to test?

currently i have a lcd tv that i have 5v standby but tv will not power on and i have 0v on all other pins

[R_J]

Re: Forcing power supply on by jumpering PSON.

It's always good practice to disconnect the main board and then use a resistor, if you don't have a 100~1000Ω resistor, find one.

[petehall347]

Re: Forcing power supply on by jumpering PSON.

buy a bag of 1k ..for now you could mix and match what you have now ...its best to use resistor to limit current if you get it wrong .

[shelby5041]

Re: Forcing power supply on by jumpering PSON.

i do have resistors ..does anyone know if there is a common faulty part on the main board that causes this on this model tv? that is repalceable

[R_J]

Re: Forcing power supply on by jumpering PSON.

i do have resistors ..does anyone know if there is a common faulty part on the main board that causes this on this model tv? that is repalceable

What model?

[eccerr0r]

Re: Forcing power supply on by jumpering PSON.

Is it more common for active high (PSON to +5VSB) or active low (PSON to GND) to turn on?

[budm]

Re: Forcing power supply on by jumpering PSON.

Active high is the most common.
A lot of Samsung has pull-up resistors on the power supply board to allow self testing without the need of using jumpers/resistors when it is not connected to the main board.
Always use the resistor in case you jump the wrong pin.