e701i-a3 no picture but backlights

[islandsborn]

Re: e701i-a3 no picture but backlights

Here are the pics:
1)1st one is with both tags attached.
2)2nd pic only with lower right ribbon tab disconnected.
3)3rd pic only with lower left ribbon tab disconnected.
Thanks for your help.

[budwich]

Re: e701i-a3 no picture but backlights

It isn't clear what you are referring to as "tags"... are you referring to cables from the tcon to the panel? If so, those are only part of the "investigation". The more important flex cables are at the lower corner of the panel. Please clarify.

[islandsborn]

Re: e701i-a3 no picture but backlights

sorry, typo. The 1st pic is the original state, with both ribbon cables attached on both corners. The 2nd pic only with lower right flat white ribbon cable disconnected from the right side board. The 3rd pic only with lower left flat white ribbon cable disconnected from the left side board. Thanks.

[budwich]

Re: e701i-a3 no picture but backlights

I don't think your problem is similar to the problems identified as the basis for this thread (ie. bad tab drivers). Why? because, the related problems identified herein typically take out the tcon in some form resulting in no picture including no "V". I think you need to check / measure all voltages "printed" at the power board to see if it is delivering what it is supposed to.

[AmpWare]

Re: e701i-a3 no picture but backlights

Thanks to the brave freakafr8 who yanked off his gate driver tabs I now have a fully usable Vizio VL470M. It uses a LC470WUH (SB)(R1) panel made by LG. i had a similar problem with it where the top left driver died a horrible death. I looked for weeks for a smashed panel with the same type of driver to use to repair this panel to no avail.

After stumbling across this thread I figured I might as well.. so I peeled the remaining tabs down the left side of the panel and what do you know.. it worked!

So now we know this also works on that panel at least. No idea about the long term reliability running 4 drivers short but hey. If it works months or years like that at least it's not in a landfill somewhere polluting our planet.

[budwich]

Re: e701i-a3 no picture but backlights

great that you were able to take a "successful plunge". One more type of set that can be saved from the dumpster under certain conditions.

[MREasyGuns]

Re: e701i-a3 no picture but backlights

Hi, I'm new here. What brought me is I have a E701i-A3 that crapped out on me last night.

Picture froze and then slowly faded to black. LED backlight works. Audio works. I can adjust the volume, and I can navigate some things from memory.

I ordered a new tcon board this morning based on advice from another forum. New board will arrive tomorrow.

I'm reading here about some driver tabs? I've tried to read as much as I can but the info is pretty overwhelming.

Question is, is there any way I check these driver tabs with limited tools before I install the new board tomorrow? I'm currently laid off and don't want to buy more parts than absolutely necessary.

Any advice is appreciated! I just want t save my TV!

[budwich]

Re: e701i-a3 no picture but backlights

Before you put in your "new" card... DO the tests with the old card by unplugging one of the corner cables and see what happens, repeat same test with the other side corner cable. IF your old card isn't "blown" (NOTE: if it is, is can be fixed as other in this thread have done the repair), you might get a picture ... maybe. IF the card is blown, you can't harm it any further and you may learn something as to which side tabs are in trouble.

You can then go from this point. I don't believe any one has come up with a test of the tab drivers... BUT visual inspection of the tab drivers on each side will likely point you to the issue.

[MREasyGuns]

Re: e701i-a3 no picture but backlights

Thanks for the reply! I'll tear in to it tonight and do as you suggested!

A few questions, if I wanted to test the transistor in question on my existing board, do I test while it is and the TV is plugged in? Sorry if this has been answered already but I'm a dummy with these things and a lot of this info is Greek to me.

Next, if I find out the "new" board is already bad (as I'm assuming most of the boards being sold were just parted out from other similarly broken TVs?) I purchased through Amazon and they're pretty good about ensuring returns with even very small vendors. But at that point if I wanted to just replace the transistor, is it soldered on the board? I'm not very good with a solder gun and if be extremely anxious to try a repair is the only reason I ask.

Last, IF I'm not able to determine which side (left or right) is bad before I install a working board, I'll basically be trying a process of elimination to find out which side is bad and then pretty much have a 50/50 chance of toasting the board again, right?

Thanks again and sorry for all the questions. I just want to try to be as prepared as possible before I get knee deep

[budwich]

Re: e701i-a3 no picture but backlights

The "board test" is done with the tv unplugged / unpowered and / or card unplugged / bench. You meter across the points of the transistor checking resistance (which should always be done in an unpowered mode).

As for replacement of the transistor, I do believe various "skill level" people have had success and if you search thru this thread even offer to provide some of the transistors involved. As for "solder gun", I think you want a soldering iron made for electronics repair, they can be had pretty cheaply on-line (walmart or equivalent) and locally at radio shack (ones that are still open... :-) ).

On the "gamble" part, yes it is a 50 / 50 gamble. However, freakaftr8 indicates that if you are "quick" with your "depowering", you may be able to stop the destruction if the screen doesn't show up in the first second or two.

I would do the visual first... then check the old card and measure a few things as laid out in this thread. Pray... :-) Try the "corner flex cable" test on each side with your fingers crossed... :-)

As I mentioned, any experience you gain will be useful when your new card comes in either as "background" to your set or as knowledge on "what not to do". :-)

[MREasyGuns]

Re: e701i-a3 no picture but backlights

Ok so I have my board out and I'm trying to test the resistance of the transistor in question. Problem is I'm not sure I know how to read this multimeter.

I have a range setting. I can set it to Ohms, KOhms, and MOhms. I get readings for KOhms and MOhms but I get no change in the reading for Ohms. The stock reading is 0.L

When I touch the leads together I get 00.00 except when I'm on the regular Ohms range and I get 000.5

Can you help me understand what setting I need to have this on when I test the transistor?

[MREasyGuns]

Re: e701i-a3 no picture but backlights

Also I meant to say that the only time I get any reading (meter stayed at 0.L) except on KOhms with the Black lead on the center pin and the red lead on the top pin with a reading of 2.5.


Edit: Scratch what I said. I found an "auto" mode on my multimeter.

Looking at the board upside down according to how it's attached to the TV:

With the black lead on the left center pin

Red lead on top right pin: 2.2 kOhms (small k)
Red lead on bottom right pin: 9.5 MOhms

Still not sure how to decipher these readings though.

I visually inspected the boards and orange ribbons on the left and right of the display and I don't see any obvious visual signs of a short or damage unfortunately.

Going to get some sleep for the night but I'm going to test the left and right sides individually with my existing boards in the AM just for arguments sake.

[budwich]

Re: e701i-a3 no picture but backlights

I think your "meter testing" appears to indicate that the transistor HAS NOT failed (assuming your test technique is good.... always "scary" when someone doesn't understand how to use a meter and is "playing" in electronics... :-) ).

I would suggest that you take a good picture of one of the side tab driver cables to give us an idea of what you are looking at to ensure we are talking about the same thing. You CAN see the tab drivers on each of the cables... right?

Further, since you have another boards already on its way, you can compare your test results with that board and go from there.

[MREasyGuns]

Re: e701i-a3 no picture but backlights

Lets see if I attached the photos correctly (I'm on mobile at the moment so it's a little wonky). If not I'll edit when I get back to my PC.

One picture is of one of the gold tabs attached to the side panel

The other two are my multimeter, 0.L being with the leads touching nothing and the 00.00 being the leads touching each other. I couldn't adequately get a photo while actually testing the board. I'll see if I can get help from someone later today.

[budwich]

Re: e701i-a3 no picture but backlights

Thanks... not really worried about the testing photos... I trust you... :-) as I think your test is correct and is likely indicate a good transistor.

Further, the picture of the tab appears to be good although it is clearly showing the driver itself. As I asked before, you are able to visibly see all the drivers in question to determine their "condition"?

IF the drivers are fine, it is quite possible that you have a power board failure... maybe. You need to attempt to verify the voltages that are printed on the power board at the various connector... carefully, with the set powered.

BUT WAIT... did you do the "corner flex cable" test that I suggested, to see what happens (ie. does the set come up in some form)?

[MREasyGuns]

Re: e701i-a3 no picture but backlights

The first two photos are the left and right drivers. Those are the correct ones to inspect right?

I haven't tested the corner ribbons yet. Before I do, would you be able to verify that the third photo indicates the ribbon that I should disconnect? They are located at the bottom corners of the set.

[budwich]

Re: e701i-a3 no picture but backlights

yes... the four or so on each side.
and those corner cables are the ones that are TEMPORARILY removed (only need to disconnect on end).

I am not familiar with the vizio tv setup but on the sharp 70 that I saved, the tab drivers ic'c are only visible from the "underside" of the flex cables... you have to remove the bezel and gently unclamp the boards from the holders to "swing" them over. I can't tell from the pictures whether you have a view of the ics themselves or just flex cable. You would think if there was an issue, it would show thru but maybe not. Anyways, just a note for you.

[MREasyGuns]

Re: e701i-a3 no picture but backlights

First picture is the other side of the driver board

D/Ced left side first and then right side. Both times I came up with LED backlight on but no picture. First time I unplugged very quickly, second time I said screw it and snapped a photo.

[budwich]

Re: e701i-a3 no picture but backlights

hmmm... ok. Well, it is likely you have to go to the next step and check voltages on the power supply board.

As for the picture of the "driver board", you don't need to look at the board itself, the tab driver IC is "embedded" / bonded to the actual cable about in the middle of the cable. When it is bad, the area around the ic gets a bit discolored from the extra heat.... can't really see the ic in the picture but don't see much of the cable.

Anyways, I think you are moving slowly in the right direction. See if you can carefully measure some of voltages associated with the power supply and go from there.

[MREasyGuns]

Re: e701i-a3 no picture but backlights

Ah I think I see what you mean about the tab driver IC. I inspected them all again and didn't see anything that appears damaged to me.

Tested the power board where the pins pins are that go out to the main board. (See pics). I used one of the ground pins for my black lead.

Results are:

T CON_ON: 3.2V
12V T CON: 12.2V
NC: No Cable
LED-BR: 2.8V
LED-ON: 3.2V
BL-ERR: 0V
12V REG: 12.29V
12V REG: 12.29V
GND
GND
GND
12V AUDIO: 12.29V
PS-ON: 3.3V
AC-DET: 3.4V
3.3V: 3.3V

Does anything seem off? I should probably find a manual for the TV...

Also, I'm assuming everything at the bottom of the board inside the thick black line is 120V AC and everything at the top is DC is that correct?