hg49nj477mfxza HIT BY LIGHTING⚡

[Super360]

Hi so i have some tv's here from a hotel that got struck by lightning, almost all of the tv's are broken now. I am curious on your guys opinions on this one. I looked at everything nothing looks burnt. I am thinking either the hdmi controller on the modbo or something on the psu. It could be anything honestly. The fuse on the psu looks good and test ok. If you guys need any pictures just ask no problem. If plugged in to power there is no light wont turn on nothing, Thanks.
Edit
Can a mod please put samsung in the thread title sorry forgot.

[budm]

Re: hg49nj477mfxza HIT BY LIGHTING⚡

I would suspect the main board, but you can verify if the power supply/LED driver board and backlights are good or not by powering up the TV without the cable between power supply board and main board connected, the backlights should come on and stay on as long as AC is applied to the power supply board, this test will only work if the power supply board has pull-up resistors for self-test.
Do you have digital meter?

[Super360]

Re: hg49nj477mfxza HIT BY LIGHTING⚡

Yes i do sir bud, I disconnected the cable that goes to the power supply to the modbo and still nothing dead as a nail. Not even a stdby light thanks.

[Super360]

Re: hg49nj477mfxza HIT BY LIGHTING⚡

tv back

[budm]

Re: hg49nj477mfxza HIT BY LIGHTING⚡

Yes i do sir bud, I disconnected the cable that goes to the power supply to the modbo and still nothing dead as a nail. Not even a stdby light thanks.

The standby light is driven by main board so it will not be on since main board is no longer connected to the power supply board t0 get the power to run.

So I would assume that you already check the main AC fuse on the power supply board, correct?

If the main fuse is OK then we need to check the DCV between the two legs of the 100uF 450VDC main filter cap to see you do have 160VDC between the two legs of the cap or not.

You are making measurement in the HOT DEADLY SIDE of the circuit so do not touch anything with your hands or body, at least plug the TV into the GFCI outlet to protect yourself.

[Super360]

Re: hg49nj477mfxza HIT BY LIGHTING⚡

Main ac fuse is good 0 ohms on meter.
167volts on the 100uf 450v dc just checked. thanks budm

[budm]

Re: hg49nj477mfxza HIT BY LIGHTING⚡

https://www.badcaps.net/forum/attach...6&d=1598070632

Check the DCV at the Cathode of the rectifier diode that is labeled with 'STB7.5V, ON 11.8V' to see if you have anything there.

[Super360]

Re: hg49nj477mfxza HIT BY LIGHTING⚡

The voltage seems to be fluctuating between normal voltage and then between 0v and 0.50v seems strand maybe you can make sense of this thanks. ok so the reason it may have been fluctuating is i think i was moving the common on the multimeter to much causing it to not detect voltage accurately please disregard that for now.

[Super360]

Re: hg49nj477mfxza HIT BY LIGHTING⚡

another one

[budm]

Re: hg49nj477mfxza HIT BY LIGHTING⚡

You are testing at 'STB 7.5V, ON 11.8V' test point without main board connected, right?

[Super360]

Re: hg49nj477mfxza HIT BY LIGHTING⚡

I was testing it connected. I will test it disconnected now.

[petehall347]

Re: hg49nj477mfxza HIT BY LIGHTING⚡

did the lightning hit the antenna ?

[Super360]

Re: hg49nj477mfxza HIT BY LIGHTING⚡

I'm not sure petehall, all i know is it turned off during a storm and is dead since.

[Super360]

Re: hg49nj477mfxza HIT BY LIGHTING⚡

Here is one with modbo disconnected.

[Super360]

Re: hg49nj477mfxza HIT BY LIGHTING⚡

I just measured the resistance to the antenna coax pin and it is showing straight short to ground is that normal?

[budm]

Re: hg49nj477mfxza HIT BY LIGHTING⚡

https://www.badcaps.net/forum/attach...6&d=1598146010

I cannot figure out what the red lines are pointing to.
The test point ''STB 7.5V, ON 11.8V' is at the Cathode of the diode DM831C as marked on the board, that is the only test point you need to test right now.

[Super360]

Re: hg49nj477mfxza HIT BY LIGHTING⚡

ok one sec

[budm]

Re: hg49nj477mfxza HIT BY LIGHTING⚡

ok one sec

Something is not right.
What did you use for ground point for the meter?

Where did you put the probes to get these readings?
https://www.badcaps.net/forum/attach...6&d=1598146010

[Super360]

Re: hg49nj477mfxza HIT BY LIGHTING⚡

I used these 2 as ground pts. For some reason if i use the voltage regulator heatsink as a ground, i get the proper 160volts on the big capacitor 100uf 450v.
If i use the grounding tab i don't get any proper voltage on the same cap for some reason.

[Super360]

Re: hg49nj477mfxza HIT BY LIGHTING⚡

Im wondering if i should just buy a replacement power supply? I just want to know which board is at fault?