Vizio E371VA lightning surge - no pic or sound

[sumdumgai]

My first actual post and I'm hoping for, and would appreciate, some good help. A nearby lightning hit knocked out our Vizio E371VA TV. The cable box got zapped, too, so I'm thinging that the surge came into the TV through the HDMI cable. The logo at bottom front of the TV lights up when power is on, but there is nothing on the screen and no sound. I don't believe there is any backlight. I replaced the power supply board with one that I bought on eBay, but it did not make any difference. Same symptoms.

To start what I hope will be a series of diagnostic steps, how do I check the power supply board to see if it is okay? I have a multimeter and have very limited electronic troubleshooting skills. I have replaced resistors and such in the past in other devices but only at someone else's direction.

Thanks for helping and being patient with me.

[jose6326]

Re: Vizio E371VA lightning surge - no pic or sound

make sure to post pictures of the board layout

it helps the guys on here to help you diagnose your tv problems

[sumdumgai]

Re: Vizio E371VA lightning surge - no pic or sound

I'll take some and post them. Thanks.

[johnboy1313]

Re: Vizio E371VA lightning surge - no pic or sound

I would suspect the main board. Once we see the pics, someone should be able to guide you through the process of forcing your power supply/backlights on with the main board disconnected. This should verify that the power supply and inverter(s) are working correctly.

[westom]

Re: Vizio E371VA lightning surge - no pic or sound

A nearby lightning hit knocked out our Vizio E371VA TV. The cable box got zapped, too, so I'm thinging that the surge came into the TV through the HDMI cable.

It's called electricity. If an incoming path exists but no outgoing path, then no electricity exists. Your answer starts by identifying both the incoming and outgoing path. Then something (not everything) in that path may be damaged.

A multimeter can measure DC voltages to three digits. BTW, a numbers that is near 12 volts can be completely defective. The number is more important than declaring "good or bad".

Measuring is a good place to start. Since nothing will make sense if a power supply is marginal or defective.

Now, identify the incoming and outgoing path. If your cable was properly earthed BEFORE entering, then that was not the incoming path.

A most common path is a direct lightning strike far down the street to utility wires. That current is incoming to every appliance via AC mains. What is damaged? Most appliances are not. What makes a best 'outgoing' path to earth? Incoming to the Vizio on AC mains. Out via its HDMI port. Into the modem. Out to earth ground via the cable.

First current is everywhere in that path - simultaneously. Much later something fails. Often damaged is the outgoing path - HDMI port.

That's the easy part. Also easy is to say, "Now, identify the incoming and outgoing path." Much harder is actually doing that. Especially since damage from a lightning strike typically has no visual indication. And Vizio will not share schematics.

[sumdumgai]

Re: Vizio E371VA lightning surge - no pic or sound

Attached are pics of five boards and entire chassis. Thanks for your help.

[budm]

Re: Vizio E371VA lightning surge - no pic or sound

Since the power LED is working, the 5vSTBY power supply is working, more likely that the main board is damaged.
You can force on the backlights by connect 1K resistor btween the PS_ON pin and the 5VSTBY pin, and another 1 K resistor between the BL_ON pin and the 5VSTBY pin to see if the backlights will come on.Notes, you muast disconnect the wires between the main baord and the power supply board to do the force on test.

[sumdumgai]

Re: Vizio E371VA lightning surge - no pic or sound

I'm sorry but you're way ahead of me. Where are the pins you are referring to, and how do I connect this resistor? Please understand I am new at this. Thank you for your help.

[sumdumgai]

Re: Vizio E371VA lightning surge - no pic or sound

OK, I think I found the PS_ON pin (3rd pin) on the power supply board on the connector going to the main board. There are two +5V pins (1st and 2nd pins) next to the PS_ON pin. Are these the 5vSTBY pins? Can I use either as 5vSTBY?

Where is the BL_ON pin?

Thanks for you help and patience.

[sumdumgai]

Re: Vizio E371VA lightning surge - no pic or sound

Picture of main board connector on power supply attached. Is the BL_ON pin any of these? Thanks.

[johnboy1313]

Re: Vizio E371VA lightning surge - no pic or sound

Can we get a pic of the other connector on the PSU?

[budm]

Re: Vizio E371VA lightning surge - no pic or sound

on/off = BL_ON
May need to have 1K resistor between the DIMM (Backlights Dimming control) and the 5VSTBY if it is an analog control type signal, just do without for now to see if the backlghts will stay on.
Check to see if the 24V is present also.
Make sure to disconnect the cable between the power supply and the main board.

[sumdumgai]

Re: Vizio E371VA lightning surge - no pic or sound

Pic of other connector attached.

[sumdumgai]

Re: Vizio E371VA lightning surge - no pic or sound

So, if I understand you correctly, I am to connect a 1K resistor between the PS_ON pin and a +5V pin on the PSU, and another 1K resistor between the ON/OFF pin and the other +5V pin on the PSU connector that goes to the main board. The cable between the PSU and the Main Board is disconnected. The other cable on the other PSU connector remains connected to the inverter (I think). These connections should force the backlight to come on. I will also measure the voltage on the 24V pins on the PSU connector, with TV off and then on.

Please confirm. Thanks.

[tom66]

Re: Vizio E371VA lightning surge - no pic or sound

That is correct. You should measure 24V when TV is plugged in with the resistors in place.

[sumdumgai]

Re: Vizio E371VA lightning surge - no pic or sound

Ran the test with resistors. Backlight came on and the +12V pins read about 12 volts each and +24V pins read about 24 each.

What's next? Thanks.

[tom66]

Re: Vizio E371VA lightning surge - no pic or sound

This would point to a defective main board.

[sumdumgai]

Re: Vizio E371VA lightning surge - no pic or sound

Can it be diagnosed and repaired? Any ideas on where to buy one if that's the only way? Thanks.

[budm]

Re: Vizio E371VA lightning surge - no pic or sound

Since the surge took out the main board, it will be real difficult or just about impossible since it may have many damaged sections, you may get one section fix just to find out the other sections do not work. For example, you may be able to fix it so it will send out the correct signals to the power supply board, but then you may find out that the tuner or the HDMI may not be working.

[westom]

Re: Vizio E371VA lightning surge - no pic or sound

Can it be diagnosed and repaired? Any ideas on where to buy one if that's the only way?

Descxribed was how a mainboard often is damaged. Identify the incoming and outgoing path. If your cable was properly earthed BEFORE entering, then that was not an incoming path.

A most common path is a current incoming on AC mains. Best 'outgoing' path to earth would be an HDMI port. Current is everywhere, simultaneously, in that path - incoming and outgoing. But often the outgoing path (HDMI) is only damaged.

Its your gamble to replace the mainboard. Since everything you can do to identify the actual defect has been done. I would get a replacement mainboard. Since damage even from lightning is typically only on one part. In your case, that is often electronics that drive the HDMI port - the outgoing path.