Vizio VL470M problem.

[truep]

Picked this last night, and it would take 5-10Min. to turn on. The yellow logo changes from yellow to a dim white when turned on but no pix or sound. per the owner, after it comes on, you can turn it off and on and it works fine until it's been off for for several hours.
When I turned it on this morning, it came right on! It had been unplugged for overnight. No caps look bad but I think I'll replace all the Power supply caps with FM and FC Panasonics and check for bad solder joints.

Anyone have any tips for other problems with this set?

[johnboy1313]

Re: Vizio VL470M problem.

Check the voltage regulators on the main board.

[truep]

Re: Vizio VL470M problem.

I did check the regulators, all looked good, but I have to wait till it fails again to check again!

[truep]

Re: Vizio VL470M problem.

Now I've screwed the pooch! I dislodged C107 on the power supply and lost it. It's an SMD but I don't know the value. Not on Electrotanya. PS is: 0500-0412-0700.

[truep]

Re: Vizio VL470M problem.

well, it seems to work without that cap. problem is I cant get it to fail! I'll leave it off again tonight. I did re-touch a bunch of solder joints though.

[budm]

Re: Vizio VL470M problem.

Is that cap (more likely to be MLCC type) connected in parallel with the electrolytics cap?

[truep]

Re: Vizio VL470M problem.

I'll check if it's in parallel. I still can't get it to fail. Maybe the re-solder worked!

[budm]

Re: Vizio VL470M problem.

If it is in parallel, then it is just a bypass cap, around 0.1~0.47uF range.

[truep]

Re: Vizio VL470M problem.

Got it to fail again! The power on/of. OFF=1.17V Power on(not working) =1.39 Power on working+1.45. Now just to trace it down and check the regulators when it fails again!

[capkid]

Re: Vizio VL470M problem.

I don't have a lot of experience with Vizio LCD TVs, but it seems like irreproducible failures are common. I have two sitting in a storage area, and the owners said they weren't working. I haven't been able to reproduce the failure in one, and the other has only failed once.

[truep]

Re: Vizio VL470M problem.

Well, I'll wait till it fails again and re-check the regulators while in failure mode..

[budm]

Re: Vizio VL470M problem.

OK, so when it failed, you need to see if the voltage on the main filter cap (450VDC) drops dow to 165~170VDC, you must measure it right at the two legs of the cap. 1.39V should still be enough to turn on the transistor on the power supply board.

[truep]

Re: Vizio VL470M problem.

The regulators looked good in failure mode. The problem is definitly on the mother board. I disconnected the 0n/off wire and jumpered a 500K resistor..Boom, on it came. I ended up reconnecting the wire and adding a 1K resistor to 5V. This broughe the on/off voltage up to where it turns on. It will still partially power off, BL/sound go off when I hit power off but the 12V stays up. Also HDMI 1 doesn't work.

Sounds like a bad transistor causing the ON/off problem, But WHERE?

[truep]

Re: Vizio VL470M problem.

Does anyone know if the Vizio logo should change from yellow to white on this model?
Mine just goes dim on power on.

[johnboy1313]

Re: Vizio VL470M problem.

It should go white at power on, at least the one I recently worked on did.

https://www.badcaps.net/forum/showthread.php?t=33594