vizio vw42l flickers

[pposey]

Hi. When I turn on my tv it will be fine for a few minutes or sometimes up to 20 minutes but then it starts to flicker then eventually the screen goes black but I can still hear the sound just find. I opened up the back of the tv to see if I can visually see any bad caps but nothing. Could anybody possibly know what may be causing this problem. Thanks in advance.

[tom66]

Re: vizio vw42l flickers

Sometimes the large 450V capacitor can fail, causing this symptom.

[pposey]

Re: vizio vw42l flickers

Is there a way to test that?

[tom66]

Re: vizio vw42l flickers

Can you post a picture of the power supply?

[pposey]

Re: vizio vw42l flickers

http://*************/photo/my-images...101122653.jpg/


If you need a better picture just let me know. This is from my phone.

[tom66]

Re: vizio vw42l flickers

Do you have a DMM?

Set your meter to 500VDC, 600VDC or 1000VDC (if it is manually ranging) or DCV if it is auto ranging.

Red probe in Volts/Ohm, black probe in COM.

Probe across that "Rubycon" 450V capacitor.

Careful -- high voltage. Do not short anything out.

Report reading. I am expecting around 390~400V if it is working. You need to measure it both with the set working and with it flickering.

[pposey]

Re: vizio vw42l flickers

OK before i attempt this i have a couple questions.

Does this tv have to powered on for this?

Probe across means exactly what?

Do not want to tear anything up lol. Thanks for your help.

Sorry i forgot to say i do have a dmm

[pposey]

Re: vizio vw42l flickers

Ok I think I got it. Shows 404v not flickering. Waiting on it to flicker so I can test it then.

[tom66]

Re: vizio vw42l flickers

Yes, the TV should be switched on.

We need a reading made while the TV is running (and working fine) and one while it is flickering (going wrong)

Also how frequent is the flickering... once it starts, every few seconds or many times a second? Does it start happening once in a while and then get worse, or does it suddenly occur?

[pposey]

Re: vizio vw42l flickers

It just does it randomly. It could be 2 minutes or 10 minutes. Then when it starts flickering it gets worse and worse until it eventually goes black but still hear sound.

[tom66]

Re: vizio vw42l flickers

I have encountered a bad 450V cap causing that very symptom. Though it degraded to the point of only having half the LCD dimly lit (after flickering badly), before going out completely on mine.

[pposey]

Re: vizio vw42l flickers

I hope it is as easy as just the cap going bad on mine. Just a couple months ago I replaced the u33 regulator on this very TV.

[tom66]

Re: vizio vw42l flickers

Rubycon are reliable, well made caps though, but it is always a good idea to consider the possiblity.

[pposey]

Re: vizio vw42l flickers

Do you think I could test this cap when the tv goes black or do I have to do that when it's flickering?

[tom66]

Re: vizio vw42l flickers

You need to do it while it is flickering. When the TV is in standby, it will measure 160~170VDC, and when it is off, it will measure nearly 0V. (It's not like a battery, will drain very fast when there is no input power.)

[pposey]

Re: vizio vw42l flickers

Ok it is still showing 404v flickering but still 404v when screen goes blank. Back light is still on

[tom66]

Re: vizio vw42l flickers

Wait, the backlight is on all the time?

[pposey]

Re: vizio vw42l flickers

yes the whole time.

[tom66]

Re: vizio vw42l flickers

I did not realise this... I thought the backlight was what was flickering.
Can you try re-seating the video cable going from the main board to the T-con board while it is flickering and see if it resolves the issue. Try both ends if possible.

[pposey]

Re: vizio vw42l flickers

That didn't seem to do anything