Verizon VT470M Service Manual

[bbushong]

Re: Verizon VT470M Service Manual

I took the cover off of the t-con board, and resecured the board with one screw. Nothing loose or burned under there... I turned the set on, and as expected, it worked. Wiggled, thumped, tapped, and tugged on every wire I could see, and not a glitch in the picture or sound. Turned it off, and turned it back on. Nothing but backlights, as before. Power seems good at all of the pins on the power supply and main board (each end of that main cable). When I turn it on, voltage at the ON/OFF pin goes to 5 volts, then when the backlights turn off, it drops to zero, then back up to 5 volts when the backlights come back on. I'm guessing that is the signal from the main board to turn on that part of the power supply? The big caps, with the set turned off, read 166V on each, and with the set on, read 392V each.

[philliesfan30m]

Re: Verizon VT470M Service Manual

i am guessing that the t-con board is bad but i would see if someone else might be able to help you further. when you say it worked you mean you had a picture of the vizio symbol? did you check the ribbon cable or cables if there are 2 going to the panel?

[bbushong]

Re: Verizon VT470M Service Manual

When it works, the VIZIO flash comes on, and I get a blue screen with "HDMI 1" or "no input" or whatever. I can change the input on the screen, play music from my USB drive, etc. EVERYTHING works fine. While it was working, I tugged, pulled, tapped on wires and connectors while the music was playing, and I had the screen working fine (music playlist displayed). Yes, I checked the ribbon cables on the t-con board, wiggled the bottom two connectors on the t-con board. I guess I don't see why the t-con board would make the backlights turn off, or make the main board send a signal to the power supply to turn off and back on...

[Glitcher]

Re: Verizon VT470M Service Manual

I'm confused, you said that the problem would be the backlights would come on but then there is "no picture". But now youre saying the backlights turn off? Which is it?

"No picture + backlights ON" = Possible Tcon problem

"No picture + NO backlights" = possible inverter issue or lamps.

[bbushong]

Re: Verizon VT470M Service Manual

When it works: It works. Everything seems to work just fine, the first time I turn it on, after it's been sitting for half a day or so, unplugged. Vizio flash screen comes on, backlights come on and stay on, and it works. I don't know about the inputs, other than USB, as I don't have a signal in my shop (yet). I can play pictures and music from my USB drive, and get a great picture. Everything works except that power indicator that's so dim I can't see it.

Once it works, and I turn it off after oh, say two to three HOURS (or two to three minutes) of working fine, I'm almost guaranteed that it won't work the next time I turn it on, and it does the following:

When it doesn't work: The backlights COME ON for about five seconds, with a blank screen. Then the backlights SHUT OFF for about THREE SECONDS. Then the backlights COME BACK ON with a blank screen. And that's how it sits.

Again, I wiggled as many connectors as I dare touch with the set working properly, even disconnected the ribbon cables coming from the top of the t-con board one at a time, and sure enough, half of the display disappeared for each one. Plugged each back in, and the display was back, working fine. Music never even stopped when I did that...

It just seems to be every attempt to turn it on, after the first, there's no picture, and the backlights come on, turn off, then come back on. Still trying to figure out at what point I can make it work correctly. Each morning, after I've let it sit for eight hours or so, it works. Not sure how short of a time it takes, or if it even corresponds to a time.

[Glitcher]

Re: Verizon VT470M Service Manual

I remember with this set, there's a big circular logo that says Vizio on the middle of the screen once you turn it on for a couple of seconds.

[bbushong]

Re: Verizon VT470M Service Manual

Yep, the logo comes up for a few seconds, then works, when it works. If it doesn't work, no logo or anything, just blank screen with the backlights on.

[Glitcher]

Re: Verizon VT470M Service Manual

Maybe possible main board issue? I had a vizio that would intermittently not turn on, it was completely random but a main board swap fixed that issue.

But it could be anything since there is more than just one symptom and not sure which board it would be linked to with this set.

[Romanmtz]

Re: Verizon VT470M Service Manual

A mainboard swap worked for me... but after a year the problem reappeared. This is that mainboards are hard to come by and usually expensive (over $200).

[bbushong]

Re: Verizon VT470M Service Manual

Yeah, that's where I'm leaning right now, but I don't see the main boards for sale anywhere... I'm willing to get one if it'll fix it, or I'm willing to attempt a fix on this one. Just don't want to get drawn into multiple expensive fix attempts... My time is experience, so I'm willing to spend that, but more than a couple hundred to fix a broken TV when I don't POSITIVELY know the problem... that's an expensive hobby...

If I can get it started again tonight, I'll see if I can do a factory reset... anybody know if it's possible to reinstall firmware or anything like that?

[bbushong]

Re: Verizon VT470M Service Manual

This is why I asked the first question about the complete service manual and how to check those specific components listed in the troubleshooting diagram. Just figured there was a reason they said to check those parts and replace if found bad. Maybe failure prone parts that can be replaced, rather than try to find a new board and toss this one. Only to find that the new one fails the same way...

[bbushong]

Re: Verizon VT470M Service Manual

I do find that I can pretty consistently get the set to start up and run if I unplug it and let it sit for about 30 minutes. I went into the factory settings (I think) by going to the menu, then pressing 1991 and enter. There is an option for 'EEPROM Init' but I'm not exactly sure what it does. I selected it a couple of times, and it just seemed to exit that menu, didn't reboot or anything that I could see.

[bbushong]

Re: Verizon VT470M Service Manual

Well, since this main board has a multitude of Lelon, Capxon, and Elite caps installed, it didn't cost me anything, and I can always use the soldering practice, I've ordered Panasonic FC and FM caps to replace all 27 of the caps. Even if it doesn't fix it, I'll get some soldering experience, and it's only costing me about $22 and some time. Since it seems to me to be a power control problem, it may work. If it doesn't, it's not costing me much... worst case, I brick the thing and part out the pieces that work...