Vizio V042L No Picture has backlights.

[philliesfan30m]

Re: Vizio V042L No Picture has backlights.

those readings were with the black lead of the dmm on the back of the regulator and each pin reading afterwards all 3 pins including the pin which does not touch the board! am i doing something wrong? if so a reply to bust my butt isn't needed! i noted exactly what i did!

[tom66]

Re: Vizio V042L No Picture has backlights.

Black lead of multimeter goes on chassis, red lead goes on each pin, one after the other.

[philliesfan30m]

Re: Vizio V042L No Picture has backlights.

ok will check again my bad.

[philliesfan30m]

Re: Vizio V042L No Picture has backlights.

ok now here are the proper readings

u15 2.08 3.33 5.03
u16 11.03 0 5.05
u17 2.07 3.31 5.03
u19 1.25 2.49 5.04
u20 .55 1.8 3.29
u21 0 1.24 2.49
u22 2.06 3.3 5.08
u44 8.35 9.62 11.03

[tom66]

Re: Vizio V042L No Picture has backlights.

The regulators look good to me.

[philliesfan30m]

Re: Vizio V042L No Picture has backlights.

i checked the 4 mosfets on the inverter board and they read this way with the dmm on 2000k ohms

q7 0,0,0
q8 0,0,0
q9 climbs up,0,climbs up
q10 10,climbs up,0


what else could i check?

[philliesfan30m]

Re: Vizio V042L No Picture has backlights.

on q7 and q8 from pin 1 to 3 i get 0 and on q9 and q10 from pin 1 to 3 i get 10k are they bad and will they cause the problem i am having?

[tom66]

Re: Vizio V042L No Picture has backlights.

Those MOSFETs are bad, is the fuse on the inverter board good?

[philliesfan30m]

Re: Vizio V042L No Picture has backlights.

yes fuse f1 is good. so all i have to replace are those mosfets?

[tom66]

Re: Vizio V042L No Picture has backlights.

With the inverter connected, do you have any 24V?

[philliesfan30m]

Re: Vizio V042L No Picture has backlights.

no i don't have 24v on the inverter board with it connected only 3 pins showed any voltage 1 was 5.0 volts the other was 4.8 volts and the last was .2 volts i think they are the a-b-c pins from the psu

[philliesfan30m]

Re: Vizio V042L No Picture has backlights.

1 is the 5volt standby and the other 2 are the a+b pins

[tom66]

Re: Vizio V042L No Picture has backlights.

With inverter power disconnected you do have 24V? Have you jumpered PS-ON yet?

[philliesfan30m]

Re: Vizio V042L No Picture has backlights.

no i don't have 24v with inverter connected disconnected. i did jump 5 volt to ps-on with a 1k resistor before should i do it again?

[tom66]

Re: Vizio V042L No Picture has backlights.

Jump PSON to 5V with the 1k and disconnect the inverter(s). Do you get 12V&24V?

[philliesfan30m]

Re: Vizio V042L No Picture has backlights.

i get 24volts if i jumper 5volt to ps-on on the connector for the inverter power

[philliesfan30m]

Re: Vizio V042L No Picture has backlights.

and i get 11.9volts on the connector that goes to the main video board

[tom66]

Re: Vizio V042L No Picture has backlights.

And if you connect the inverter, I'm guessing it drops out. Only make the connection after disconnecting the power cord from the plug.

[philliesfan30m]

Re: Vizio V042L No Picture has backlights.

yeah i don't have 24volts at the inverter board and now the orange light isn't on either with it hooked up with the jumper

[tom66]

Re: Vizio V042L No Picture has backlights.

Well you won't have orange light if you disconnected power from main board.
I'd suggest you replace those MOSFETs and look carefully at the controller chip on the inverter for signs of burning.