Vizio VX42L - will not come on

[doanh]

I could use some guidance on this.

My Vizio VX42L has no light, no vizio icon, no sound, nothing.. when plugged in.

I checked the power supply and the inverter board, no bulging caps at all. I even check the fuse, it is good.


I measured the regulators on the inverters and it is around 8.4k.

I read some where it was suggested "If the logo does not light up when plugged in, replace the power & the video board also known as main unit"

any suggestions would be appreciated.

[doanh]

Re: Vizio VX42L - will not come on

got some pictures so you can see what I got.

thanks in advance.

[retiredcaps]

Re: Vizio VX42L - will not come on

On the power board, there are 3 sets of connectors. Do you measure any DC voltage on them?

[PlainBill]

Re: Vizio VX42L - will not come on

And this set has the notorious LG Master / Slave inverters. If you see standby voltage out of the power supply, try unplugging the inverters.

PlainBill

[kingofcoins]

Re: Vizio VX42L - will not come on...>

Check the post #95 here for my similar fix...

https://www.badcaps.net/forum/showth...t=12766&page=5

[doanh]

Re: Vizio VX42L - will not come on

Thank you very much for the suggestions.

I checked the voltage measurements at the three connectors and it was all zero volts! what in the world? am I measuring at the wrong pins?

I do not hear the relay next to the main fuse opening or closing but am not sure how loud it is supposed to be.

kingofcoins as for the link, since mine does not even have the logo lights on, I am not sure if it is the same but I will keep that in mind.

At this point, the power supply is bad but I do not know where else to check next. I am not an electrical engineer or electronics technician. I am just a tinkering engineer.

[retiredcaps]

Re: Vizio VX42L - will not come on

I checked the voltage measurements at the three connectors and it was all zero volts! what in the world? am I measuring at the wrong pins?

What about the 5V SB pins? Put your black probe on a ground screw and red probe on the 5V SB pin. Put your multimeter to 20V DC. Your tv must be plugged in as well.

If you still have 0V, check all your fuses. Power off, unplug the TV, and the measure resistance of the fuses. A good fuse should read less than 1.0 ohms.

[hijodalgo]

Re: Vizio VX42L - will not come on

As retiredcaps said,,check for 5 volts at the power supply first,and then,go to the main board and check two fuses there,,one of them must have 5volts, PS_on must have 2.6 volts when you press power,that will make the power board run and then check for 15 volts and 24 volts..if is no power at all,better check the inverters boards,,maybe some BAD CAPS there..

[doanh]

Re: Vizio VX42L - will not come on

thanks for the advice. the SB voltage was 5.15V at the measure points in the pic.

I tried to push the on button without the other boards connected and the measurement is still the same.

As for fuses, these are SM fuses? how do I identify them?

thanks again

[retiredcaps]

Re: Vizio VX42L - will not come on

the SB voltage was 5.15V at the measure points in the pic.

As for fuses, these are SM fuses? how do I identify them?

Fuses are marked with a "F" on the PCB. For example, it might be F100.

Since you have 5V standby power, re-read PlainBill's post #4.

[hijodalgo]

Re: Vizio VX42L - will not come on

Probably power board failure,check for bad caps,and smd transistor open base to emiter on the PB..

[doanh]

Re: Vizio VX42L - will not come on

I checked the fuses as shown and one of the SM fuse is blown. Maybe this was the problem.

I have never messed with surface mount stuff before. How can one remove this fuse? I have a desoldering gun but I am not sure if I can use it on surface mounts.

What still bothers me a little bit is that this has nothing to do with the Power Supply board...

[doanh]

Re: Vizio VX42L - will not come on

regarding plainbill's comment about unplugging the inverter board. What does this mean?

Nothing is plugged into the PB at this moment but the wall outlet power cable (during measurements periods only).

[doanh]

Re: Vizio VX42L - will not come on

how does one identify the rating of the smd fuse to replace. by color?

thanks again for all the help.

[PlainBill]

Re: Vizio VX42L - will not come on

the power supply has two sections - the standby supply, and the main supply. The main board includes a standby processor section which controls the main supply via the PS_Enable (or a similar label) line. To test the main supply, you must have the main board hooked up, or supply 3V to the enable line.

SMD fuses usually have a letter which indicates their value. Often the board itself will have a warning 'Replace only with 4A, 63V fuse'.

PlainBill

[doanh]

Re: Vizio VX42L - will not come on

thank you. the fuse is E 3A so I would say it is a 3 amp fuse but am not sure the voltage rating. 24V or 35V I wonder. I am checking on google for some sort of smd guide..

luckily, I found a local seller on CG with a busted screen (victim of Wii).. I bought his TV and changed out the electronics.

By the process of elimination, it is the main board. I could venture to guess that it is this SMD fuse that is causing the problem.

At least I have spare boards now! Thank you everyone for all your inputs.

[doanh]

Re: Vizio VX42L - will not come on

Plainbill. just curious, my PS has primary and secondary instead of main and standby. It is safe to assume that the secondary is the standby power section?

[PlainBill]

Re: Vizio VX42L - will not come on

Plainbill. just curious, my PS has primary and secondary instead of main and standby. It is safe to assume that the secondary is the standby power section?

No. I would label the standby as the primary (as in first) power supply, but a very good case could be made for doing it your way.

PlainBill

[brnrubbr]

Re: Vizio VX42L - will not come on

FYI, narrowed down an issue for a 42" Vizio to a bad DLA001D. Replaced the IC with a STMicroelectronics L6598D. All is well!

Issue: 5VDC good, 12VDC bad, 24VDC bad on power board.