Verizon VT470M Service Manual

[bbushong]

Howdy guys and gals! I have hapened across a VT470M that a neighbor was discarding, and figured I'd se if I could resurrect it. First thing I'd like, though, is a COMPLETE service manual for it. I've downloaded a few, and they're all missing pages 27 to 63, which I assume (from the table of contents) explains everything at the component level. For instance, the documents that I have say, at one point, something like check R4145, Q404, Q414, R4158, Q405, Q415. But there is nothing saying what they are, or HOW to check them. I found those items after searching a while, but I'm not sure what readings I'm looking for. Anyone have access to the complete manual? Thanks in advance!

[budm]

Re: Verizon VT470M Service Manual

The service manual will not tell you how to test resistor (R), or Transistor (Q), or MOSFET (Q). When you find out what the P/N are on those Transistor/MOSFET then you can look up the spec and find out the pinout and what kind of Transistor- NPN or PNP, same for the MOSFET- N-Channel, or P-Channel.
So look up the number and then we can tell you how to test some of them.
Resistor, you just check the resistance based on the color code. What kind of tools do you have?
http://www.elexp.com/t_test.htm
Just Google " How to test xxxxxxx"

[bbushong]

Re: Verizon VT470M Service Manual

I've got a couple of digital volt meters and soldering irons. I have an o-scope that I'm itching to learn about; got it for another project that is on hold...

[bbushong]

Re: Verizon VT470M Service Manual

Wow, messed up on the FIRST word of my first question... should be Vizio VT470M manual... guess that's what I get for using my phone for this...

I'll see if I can post some pics of the transistors I'm trying to check. They're surface mount, and teeny (for me, anyway). Not sure how they'll come out from my phone. I'm off in two hours, so it may have to wait until then.

[bbushong]

Re: Verizon VT470M Service Manual

I guess, before diving too far into this, I should ask if you think it's even possible for me to test and/or replace the smaller components on this board. The specific ones in question are Q404, Q405, Q414, Q413, R4145, R4158, etc. I'm willing to try it, as the TV was free... But if it's going to be an exercise in futility, I may look for a replacement board if I can find one.

[bbushong]

Re: Verizon VT470M Service Manual

The only markings I see on those specific transistors are H1A and H2A.

[philliesfan30m]

Re: Verizon VT470M Service Manual

i'm not an expert like some of the guys here but i would suggest taking pics of all the boards on the tv. and what is the tv doing when it is plugged in and you try to turn it on? are you just trying to fix it or do you just need the manual? if you are just trying to fix it i'm sure someone will be able to point you in the right direction without a manual because the people on here know their stuff.

[bbushong]

Re: Verizon VT470M Service Manual

Really, I'm trying to get a feel if I should even think about attempting the repair. I'll post a full description of what is going on when I get home. Just too much of a pain to type on this phone. Similar to another problem I saw with one of these, for which I didn't see a solution posted.

[budm]

Re: Verizon VT470M Service Manual

OK, it is VIZIO. So post good clear pictures of the boards will help. First thing is to look for any sign of burn, broken parts, then voltage testing will be next start with the DC voltage on the large filter cap (450vdc rating) on the primary side.

[bbushong]

Re: Verizon VT470M Service Manual

Yeah, VIZIO. I was on a VERIZON phone, so I don't know if it autocorrected it, or if I messed it up. Probably the latter...

Okay, I've got a video of the TV starting up, working, great. The only thing that's strange with it WHEN IT WORKS is that the VISIO power indicator never turns amber. It's always dim white/gray when it's off, and when it turns on (every time, when it works or not), it just gets a little brighter, then dims down again where you can barely see it. When the set does NOT work, the power indicator does the same thing, the backlights come on for about five seconds, then go out for about three seconds, then come back on and stay that way indefinitely.

I checked the voltage at the large caps on the power supply, and each is 166V. I don't see any burn marks for puffed capacitors, and the voltages, from what I can tell (and that ain't much!) match the markings on the boards. Checking U701 and U702, I get 9.1V and 12.0V out, respectively... Those are just ones that I've checked from perusing this forum...

Working on getting some pictures sized right to post. Uploading keeps failing me...

[bbushong]

Re: VIZIO VT470M Service Manual

Okay, here are some pictures of the boards. Not sure how detailed you want or need... Bits are free (Got a 64GB card in the camera), so I can take as many as will help out.

[philliesfan30m]

Re: Verizon VT470M Service Manual

i know a lot of people have had problems with the inverter boards with vizios but i haven't heard of anything with this model. when the backlights come on and stay on do you have a picture and everything works ok? or is just the backlight on and you don't have a picture?

[bbushong]

Re: Verizon VT470M Service Manual

When it doesn't work, I just have the backlights with no picture. The backlights come on without fail every time I turn it on.

The first section in the troubleshooting procedures is for no power (no LED indicator), and I figure that's a good place to start, since the indicator is glowing so dimly.

[Tiezane]

Re: Verizon VT470M Service Manual

That inverter board looks like either someone already did a repair on it (look around the legs of the caps and the inverters themselves) or that was a piss-poor job at the factory...

[Glitcher]

Re: Verizon VT470M Service Manual

I repaired this set a while back. Keep in mind that there are actually two inverter boards for the panel. There should be another one that is under the metal plate where the main board is screwed on. There was a couple bad FETs on the inverter board which was the problem, but im not sure if it is similar to your problem.

There vizio logo doesnt actually change to amber for this particular set when this it is turned on. It'll just get a little brighter when on and dimmer when off, or vice versa (i forget which).

But you said when it doesn't work the backlights would go on but there is no picture. Then I would guess the Tcon board. (Bad panel is also possible since its intermittent)

[philliesfan30m]

Re: Verizon VT470M Service Manual

i was thinking the same thing as tiezane that it looked like someone already tried to repair the inverter board. and i also agree with glitcher that it is probably the t-con board which is the cause but could also be the panel. the t-con board is at the top middle of the chassis still under that metal casing with the 2 connectors going to it in your last pic. i would suggest that you see if you have those 2 connectors properly connected and then turn the tv on and wiggle the connectors to see if it gets better or worse. or it could be the connector going to the panel from the t-con board that is rubbing on the panel i saw someone had a problem with that connector. i don't think you should focus on the brightness of the vizio light when it is on or in standby. thats just my opinion.

[bbushong]

Re: Verizon VT470M Service Manual

I've unplugged and plugged the two connectors to the t-con board previously, with no change. I actually unplugged and plugged them in with the TV on and not woorking, and the display didn't change or flash. I'll try it again tonight with the set working (if I can get it to work one time), and see if wiggling wires makes a difference.

[philliesfan30m]

Re: Verizon VT470M Service Manual

i would check the ribbon cable that connects to the top of the t-con board to the panel and see if putting pressure on it changes anything it might be shorting out on the chassis causing it to be an intermittent problems. if you take those 3 screws out to take the metal cover off make sure you use 1 of the screw to attach the board so it is grounded. just a reminder

[bbushong]

Re: Verizon VT470M Service Manual

Okay, I'll give that a try, too. Thanks for all the suggestions.

[philliesfan30m]

Re: Verizon VT470M Service Manual

any luck?