TV Repair - Accidentally brought back to life with my DMM!

[joshzstuff]

I was probing voltages on the pins of the TVs Logic board (going to the Time-Control Board) and suddenly it came to life!
The power supply did not sound healthy to me, but maybe I'm mistaken.
I'm trying to get the video uploaded to listen to the sound it makes.

After I power cycled the TV it was was dead once again and I could not reproduce the probing that brought it to life.

Specs:
Vizio LED TV E70u-D3 (70")
Info PDF https://support.vizio.com/s/article/E70u-D3-Model-Information?language=en_US

Original Problem:
It was reported to me that the TV became increasingly unstable.
It would turn itself off after just a few minutes, and there was distortions on the screen.
Finally the TV would display nothing at all.
The power cable was replaced, and the TV was power cycled. Both attempts seemed to correct the problem, however now the white power LED will illuminate for a few seconds and go out after a minute, there is no longer any display shown on the screen.

Trouble shooting Technique.
I intend to check all the power supply capacitors, then move to stand by power, voltage regulators, and voltage levels on other boards.

The red label "12.3V" is the pin I was probing when the TV came to life.

With the TV plugged in, but in stand by mode, there is 0volts on these pins, however after the power button is pressed 4/7 of them get 12.3 volts.
I was checking this when all the sudden the power supply booted up (noisily) and the screen lit up.
I was able to feed a signal into the TV, and it displayed it just fine (just a noisy power supply to my ears)

The 2nd photo shows my diagnostics of the Power Supply.
Pin 13 labeled "PS-ON" has 0 volts in standby mode and 5v when the power button is pressed.
The voltage is persistent on this pin, however the "power" led only stays lit for about 5 seconds before fading out. After witch you can again power it on for a brief time.

I am not sure if the power supply quality is the underlying issue, or if there is a fault on the main logic board.
Can anyone suggest how I can test this?

Thanks!

 

[Harald Kapp]

You may have a cold solder joint (or more than one, more likely). By probing with the test probe you may have pusjed on such a solder joint and re-established the connection. Inspect the solder joints in the area where you were probing visually and re-solder any bad looking joints.

 

[joshzstuff]

You may have a cold solder joint (or more than one, more likely). By probing with the test probe you may have pusjed on such a solder joint and re-established the connection. Inspect the solder joints in the area where you were probing visually and re-solder any bad looking joints.

That is a valid theory.
So here is a closeup shot of the terminal in question, tell me what you think.

Here is the top view:

I have some concerns about reworking this connector.
Does this look bad to you? It seems like a good place to start, but I should mention that once working the TV continued to work until I power-cycled it. And I left it alone while I cycled it. could it be that the DMM connected to ground did something, rather than the probe physically restoring the connection?

Another concern is that I may cause a fault. There is a very fine barrier there. (or is that just the solder mask?)
If you still think I should solder it I will, but here is the video of the power supply noise:

 

[Harald Kapp]

The joints don't look bad. However, re-soldering will not hurt wehn done correctly.
Your theory about grounding via the meter cannot be dismissed either. In that case you'd have to find the spot where this happened and trace from there to any component that may be defect.

The PSU doesn't sound good - as if tehre was arcing somewhere which could be due to bad insulation or a faulty regulation. Impossible to diagnose from afar. Can you check the different output voltages of the PSU against the expected values?

 

[joshzstuff]

Anyone know how to ID the values of these caps?
The markings are 1545(M)

 

[joshzstuff]

So, the values were underneath , they are 25v 1000uF & 450v 100uf respectively.
I started removing and testing capacitors:

I won't have access to a proper ESR meter for a few days. In the mean time this is the best I have:

The reading fluctuates between 0.016 Ohms and .31 when I first took it out (maybe too hot?)

 

[Harald Kapp]

These readings are o.k., fluctuations are not a big issue. I don't think these caps are an issue.