Vizio E460ME 46" LCD Color Bars

[mdmccool]

Hi Guys-

New to the forum and modern TV repair in general. I am looking for a little help on a Vizio TV I have. My main interest is in repairing antique radios and TV's, all vacuum tube based stuff so I am a little out of my element messing around with this modern stuff.

I have a Vizio E460ME 46" LCD tv that is suffering from large vertical bars of color on the right side of the display, exactly half. Unfortunately this model has two separate T-Con boards that are directly connected through ribbon cables to the display - can't replace the board without replacing the entire display. I've gently played with the ribbon cables that are glued to the display, unseated and reseated cables that go from the main video board to the T-Con and nothing seems to help. From everything I have read it seems that the diagnosis for most line problems, vertical or horizontal are diagnosed as ribbon cable problems or "replace LCD" display.

I know many of these circuit boards are basically unrepairable unless you have surface mount equipment - many of the components need a magnifying glass to be seen!

I am thinking a good first step is to measure voltages to see the health of the power supply. No obvious failed caps. The video/tuner board also has quite a few electrolytics - wondering if one of these could cause the problem but I am not sure how these circuits work.

The video board is connected to the main T-Con via a cable of about 30 or so wires. Then there are two small ribbon cables that connect one T-con to the 2nd T-Con. (I have re-seated these with no improvement) I am assuming each T-Con is responsible for half the screen - so I am assuming the T-Con responsible for the right screen has failed, hence my problem.

Not sure how the signals are processed and was wondering if maybe I have a bad cap or to on the video board.

Thanks for any help,

Matt

[mdmccool]

Re: Vizio E460ME 46" LCD Color Bars

I was able to check the various power supply voltages and all seems well - the 24 volt supply measures a tad high at about 24.6 but I would assume that is within tolerance.

I cleaned all ribbon cables/connectors with deoxit and no change.

If I disconnect the ribbon cable that drives the right half of the screen, that half goes completely white - an indication that the panel is OK?

Is it possible that this could be a main video board problem and not the T-Con? There is a cap I noticed that *might* look slightly bloated.

Any ideas?

[mdmccool]

Re: Vizio E460ME 46" LCD Color Bars

Here are some photos. Just wondering if there is any chance this could be a main board problem. Any help would be appreciated.

[tom66]

Re: Vizio E460ME 46" LCD Color Bars

It's very rare for a main board to cause a regional defect.
A t-con can cause it in rare situations.
Often times it is the panel itself though.

[Dgtech]

Re: Vizio E460ME 46" LCD Color Bars

I have a good question about this set cause I'm working on a similar set. These Vizios are seeming like the T-Con section is built into the main board as seen above. Is this true? I see that they combined the power and inverter section in mine E420VO.

[tom66]

Re: Vizio E460ME 46" LCD Color Bars

On this model the T-con is in the panel itself.
I say that but it's not really a T-con any more. It's just differential LVDS lines driving the LCD chip on flex directly instead of going through a T-con.

[mdmccool]

Re: Vizio E460ME 46" LCD Color Bars

Thanks for your reply Tom, much appreciated. Was wondering if it was worth checking caps, etc on the main board or not (been looking for an excuse to get an esr meter). I assumed if it was a main board problem the entire screen would show the defect, not half.

If the TCon is built into the screen, what are the two small boards called at the top of the screen? (Still new at this).

I have three sets here that have various "line" problems...hopefully I can get one going...

Thanks again,

Matt

[tom66]

Re: Vizio E460ME 46" LCD Color Bars

Those are panel driver boards, I am not sure if they have a name as they are not replaceable.

[mdmccool]

Re: Vizio E460ME 46" LCD Color Bars

OK - thanks again.

[mdmccool]

Re: Vizio E460ME 46" LCD Color Bars

I messed around with this set again last night. I thought it would be worth a try to gently heat things up with a heat gun to see if I could get any response. I started with the left panel driver board (the side with the screen defect). After about 30 seconds the vertical bars disappeared and the set played perfectly!!! I let things cool and expected the problem to reappear but it never did. I let the set play for about two hours, cycled it on and off a few times. Let it sit overnight and tried it again this morning and still good.

I don't expect this to be a permanent repair but so far so good.

[tom66]

Re: Vizio E460ME 46" LCD Color Bars

You probably have bad tab bonds then.

[mdmccool]

Re: Vizio E460ME 46" LCD Color Bars

I've finally localized the problem with this set. It has a bad (open) tiny resistor on the right side driver board. If I bridge the resistor with a low value resistor (100 ohm +/-) the TV works fine. I would like to replace it with the correct value resistor and I can't find a service manual or schematic to ID it.

I need to identify RX21 and also CD17.

Anyone have info for an E460ME?

Thanks,
Matt

[mdmccool]

Re: Vizio E460ME 46" LCD Color Bars

Here's a photo of the board and component:

[tom66]

Re: Vizio E460ME 46" LCD Color Bars

It's plausible that the same resistor could be found on the other side of the panel, or on another tab bond.

[ecking767]

Re: Vizio E460ME 46" LCD Color Bars

excellent troubleshooting !!!

[Th3_uN1Qu3]

Re: Vizio E460ME 46" LCD Color Bars

All the resistors on there will be the exact same value. So just measure its neighbors. The capacitor is likely to be 1uF ceramic judging by its size.

[mdmccool]

Re: Vizio E460ME 46" LCD Color Bars

It's plausible that the same resistor could be found on the other side of the panel, or on another tab bond.

I thought the same thing, but the left driver board is quite different and I didn't want to assume anything.

excellent troubleshooting !!!

Thanks! Wish they all worked out this way...

All the resistors on there will be the exact same value. So just measure its neighbors. The capacitor is likely to be 1uF ceramic judging by its size.

Really? All the same value - that's easy. How can you tell? It's not that I don't believe you, I'm just curious.

[ecking767]

Re: Vizio E460ME 46" LCD Color Bars

Here's a photo of the board and component:

your in luck, this panel is found in a Westinghouse LD-4655VX I have it on my work bench now, All resistors are 82ohm

[Th3_uN1Qu3]

Re: Vizio E460ME 46" LCD Color Bars

Really? All the same value - that's easy. How can you tell? It's not that I don't believe you, I'm just curious.

Look up how the LVDS protocol works and you'll understand. The signals are driven in differential pairs, so resistors in series with LVDS lines will at least be in pairs as well... In practice, due to both economic reasons and interface design, all resistors will be the same value. Same is generally true for any data bus. It makes sense - easier, cheaper and less confusing. The resistors are there to present a fixed impedance.

your in luck, this panel is found in a Westinghouse LD-4655VX I have it on my work bench now, All resistors are 82ohm

[mdmccool]

Re: Vizio E460ME 46" LCD Color Bars

your in luck, this panel is found in a Westinghouse LD-4655VX I have it on my work bench now, All resistors are 82ohm

Thanks for the info! I checked mine and they are all indeed 82ohm.

Look up how the LVDS protocol works and you'll understand. The signals are driven in differential pairs, so resistors in series with LVDS lines will at least be in pairs as well... In practice, due to both economic reasons and interface design, all resistors will be the same value. Same is generally true for any data bus. It makes sense - easier, cheaper and less confusing. The resistors are there to present a fixed impedance.

Thanks for the explanation - makes sense. Much appreciated.

...Now lets see if I can actually replace this tiny little bugger...