Bad driver(s)? Sharp LED TV

[scuby]

Re: Bad driver(s)? Sharp LED TV

Ok.

So I threw a new Tcon board at it. Certified good used and working.

Photo 1 shows the "best" result with the original Tcon board.

Photo 2 shows the result with the "new" Tcon board.

It's not consistent. If the Tcon was malfunctioning I'd expect replacing it either to remedy the TV by replacing it. If it's not the Tcon i wouldn't expect it to change anything as it does. If it isn't the Tcon I'd expect the "same" malfunction.

To re-iterate: when disconnecting 2 ribbons from either side of the Tcon the TV shows a half white screen.

Reset doesn't get service mode. There is no visible menu. All video signal is missing. Audio is present.

[budwich]

Re: Bad driver(s)? Sharp LED TV

sorry but your first post talks about a 50 in sharp.... is the one that you are working on with these pictures a 70in? What exactly is the model number?

As far as the "certified good and working"... by who and did you see this?

[scuby]

Re: Bad driver(s)? Sharp LED TV

sorry but your first post talks about a 50 in sharp.... is the one that you are working on with these pictures a 70in? What exactly is the model number?

As far as the "certified good and working"... by who and did you see this?

I wash oping you'd replay as to your success the past.

At the end of post two I specify the model number of this set:

The European model designation is: LC-70LE835E
The US model designation is: LC-70E735U

The certified good is unit supplied by a TV repair tech. There's a warranty and I've already contacted him about "new" unit.

It could be at fault though I'm hesitant to chalk it up to it.

[budwich]

Re: Bad driver(s)? Sharp LED TV

sorry... I wasn't trying to "cast" any "despair" towards anyone... just trying to understand where things are at exactly... plus my reading ain't so good ... :-)

So a couple of things... first when you have all cabling plugged in, does the set display anything and stay displaying... no flash codes?

Next... have you looked at the side tabs of the set if visually you can see any sign of heating / "abnormal" when compared to others?

Next, beside the tcon to panel cabling, there are a couple of "points" where "flex cabling / ribbons" can be disconnected / unclamped? These provide ways of isolate the panel "sections" so that if there is a panel issue, potentially, it can be isolated away while the rest of the panel still work "almost". At the bottom corner, on each side there is a small ribbon cable which connects the bottom edge boards to side boards. You can unclamp one end of this cable and power up the set to see what the result is. You can do the same with the opposite side. This test allows the tcon to still fully drive the panel because all of its cabling is intact but "isolates" the side drivers IF they are bad and causing issues. Depending on the results, there are some other points that also help isolate things. Post any results and go from there. I am leaning towards a problem with bottom edge boards (some smd component) but have seen issues / posts where a side driver did some "bad stuff" to the overall display.

One other point... this.... "PS: with one side disconnected from the Tcon the white side will dimm after a few seconds as if saving power. Hitting the menu button or volume will trigger the screen to illuminate fully again. It seems to respond that much at least. It also does this when displaying the blue screen which varies in size when turned off and on again but is always on the same side." which you mention previously. The "dimming" is usually a result of the set detecting NO valid input and hence the dimming / power saving kicks in. Are you ever able to bring up any type of menu?

[budwich]

Re: Bad driver(s)? Sharp LED TV

allright: here's wat I've done:

I have 4 cable/ribbons running from the Tcon to the panel. My backlights always come on every time I power up the set. I have no codes flashing at any time.

I have a source playing verified by it's audio.

Unplug the right most cable/ribbon: corresponding half of screen lights up mostly white/grey but lot's of colored lines. See Pic 1

Unplug the second cable from right: corresponding half of screen goes completely white. See Pic 3

Same is true of the left. 1 cable results in a more colorful lighting up of the screen. Disconnect both it's all white. See pic 2, it goes fully white like pic 3 on the other side too.

Disconnect all four and the set switches off.

What can we conclude from this?

sorry I missed this post... :-(

That is the right kind of test with the tcon but it gets you nothing? That usually points to a problem with getting some signal into the panel as the black side should see something.

That could either mean it isn't being sent or it can't make thru to the panel.
You are likely going to have to check some voltage points which should be printed / labelled on the tcon and / or the bottom edge boards... things like "V..." (eg. VCOM and such). These might highlight the issue. Since you have tried two cards, then if there is a voltage problem, it is likely at the panel / edge boards. IF things look OK, then I would say, the main board is an issue. More likely since you never see any flash codes.

[scuby]

Re: Bad driver(s)? Sharp LED TV

sorry I missed this post... :-(

That is the right kind of test with the tcon but it gets you nothing? That usually points to a problem with getting some signal into the panel as the black side should see something.

That could either mean it isn't being sent or it can't make thru to the panel.
You are likely going to have to check some voltage points which should be printed / labelled on the tcon and / or the bottom edge boards... things like "V..." (eg. VCOM and such). These might highlight the issue. Since you have tried two cards, then if there is a voltage problem, it is likely at the panel / edge boards. IF things look OK, then I would say, the main board is an issue. More likely since you never see any flash codes.

No that test gets me nothing. I posted some pictures. I get one half white, the other half remains black and imageless.

Excellent post if not simply due to being informative and arming me with new things to try. I hate not understanding things. I have a hard time letting it go in that case.

So I think by reading your last post you read mine some more and got some answers however:

I will check the Tcon tomorrow am (1am here in europe now). If/when I find values I'll measure them and report back.

Good catch on the significance of the dimming, my other Sharp TV does the same. Hadn't made the connection. On that note it seems indeed to be completely missing a video signal at times and sometimes (with the blue, getting a small scrambled amoutn through the LVDS). Also what the Tcon test showed. Not a single pixel gives me image of any kind. No menu, nothing. No codes and the backlights always fire up just fine.

So I'll report back after testing the Tcon voltages if I can find them.

So it is possible that even though there is sound the video processing part of the Main Board is busted?

I would be happier than might seems reasonable to get this thing going

I'll also inspect the side tabs for heat etc. All the other boards and connections are clean, very little to no dust and no signs of any damage or heat in the set at all. Every capacitors looks healthy etc. Visually the set is very clean. It's about 4 years old and saw very little use I was told.

thanks

EDIT: with all cabling plugged in no codes, it turns on the backlight will auto detect a signal and I can hear audio. Sometimes it will show the blue screen sometimes the screen is completely blank (see pics on previous post). No menu nothing. It has played like that for an hour or more just to test heat getting into the components. Only change seems to be the longer it's on the less likely the "blue portion" of the screen tends to light up at all.

[scuby]

Re: Bad driver(s)? Sharp LED TV

Unfortunately there is no information on the Tcon board.

I can probe the pins but I'm not going to know what's what obviously.

potential next step?

[scuby]

Re: Bad driver(s)? Sharp LED TV

All of the following tests were done with signal input as verified by the audio playing. Not once did any image display.

Along the bottom edge of the TV there are 4 larger white ribbon connectors. Disconnecting the left side connectors result in 1/4th of the screen displaying fully white from top to bottom. Disconnecting the right side the same.


Along the bottom left and right side and in the far left bottom and right corner there are smaller ribbon connectors. The best I could do without fear of damaging something was to unclip them. Removing them seems like damage is inevitable.

Unclipping them had no effect on anything.

On the topic of "dimming" I noticed, as I was streaming youtube clips, that: in between clips when the video signal goes black on a working tv that the LED backlights also respond to this, much the same as the aforementioned darkening if there is no input.

So the LED's are getting some information about video signal at least.

The connectors all look healthy btw, no heat or anything of note to be seen.

Please see attached pictures for reference.

[budwich]

Re: Bad driver(s)? Sharp LED TV

Unfortunately there is no information on the Tcon board.

I can probe the pins but I'm not going to know what's what obviously.

potential next step?

so you are saying there is not "labelling" on the tcon anywhere? don't expect to see "12v" or things like that... more in terms of "names" that "suggest" an important "pin/location/testpoint". The same applies to the bottom edge boards. :-(

Your views appear to be limited exposure to the edge boards... I do believe some of the framing / bracing / members can be removed a bit to get easier access to things. Not sure it would help.

Further your other post about dimming and signals and button pushes is interesting.... potentially indicating a main board problem BUT I think some of the dimming is associated with tcon as opposed to the main board.

Further back to labelling, there is also likely some on the main board, perhaps there are some of interest there that can be checked.

[budwich]

Re: Bad driver(s)? Sharp LED TV

All of the following tests were done with signal input as verified by the audio playing. Not once did any image display.

Along the bottom edge of the TV there are 4 larger white ribbon connectors. Disconnecting the left side connectors result in 1/4th of the screen displaying fully white from top to bottom. Disconnecting the right side the same.


Along the bottom left and right side and in the far left bottom and right corner there are smaller ribbon connectors. The best I could do without fear of damaging something was to unclip them. Removing them seems like damage is inevitable.

Unclipping them had no effect on anything.

On the topic of "dimming" I noticed, as I was streaming youtube clips, that: in between clips when the video signal goes black on a working tv that the LED backlights also respond to this, much the same as the aforementioned darkening if there is no input.

So the LED's are getting some information about video signal at least.

The connectors all look healthy btw, no heat or anything of note to be seen.

Please see attached pictures for reference.

If I understand your reference to the "four white connectors" and the disconnecting... it appears to give a "1/4" screen white... this indicates a totally isolated quarter "panel" which only relies on "common voltages / grounds" to cause the LCD pixels to "transmit" backlight while the rest of the panel should be doing its "normal job". This allow the tcon to fully drive the panel and "usually" takes out a portion of the "duplicate side drivers" (depending on which side) along with some of the bottom drivers.

It still has not fully pointed the finger yet because it is possible that the tcon signal is not getting into the edge board because of a missing component voltage either not in the tcon (likely not because you have tried 2 boards) or because a component at the edge board is fubarred.

You are getting closer... I think to ascertaining things.

[budwich]

Re: Bad driver(s)? Sharp LED TV

I am thinking your problem is up from the tcon. In post 20, the one picture with the blue "quarter screen" appears to show "part" of a display "icon"... that potentially being maybe something like "no signal check cabling" box that appears on some sets in the middle of the screen... look at your picture... you can see a small corner of the "box" in the "middle / center portion".

Perhaps you might take a closer look at the lvds cable and connectors at both ends visually. If possible, you might see if you can do a continuity test on the cable ... tough but doable with some small pins on the probes or otherwise.

One other point... have you checked any other input types?

[scuby]

Re: Bad driver(s)? Sharp LED TV

Hmm. So the Tcon communicates back with the main board? As the dimming is of the LED's.

Here I made a video. Hope that helps gives some clarity as well as maybe spark some more testing ideas.

I can get a mainboard cheap enough in China. Good used for 24 dollars. Takes two weeks to get here. Might just order one up.

It just seems like there is NO video signal getting through.

[nomoresonys]

Re: Bad driver(s)? Sharp LED TV

Are you getting about 12 volts on each side of the fuse on the tcon, red probe on each side black probe on metal chassis.

[scuby]

Re: Bad driver(s)? Sharp LED TV

I am thinking your problem is up from the tcon. In post 20, the one picture with the blue "quarter screen" appears to show "part" of a display "icon"... that potentially being maybe something like "no signal check cabling" box that appears on some sets in the middle of the screen... look at your picture... you can see a small corner of the "box" in the "middle / center portion".

Perhaps you might take a closer look at the lvds cable and connectors at both ends visually. If possible, you might see if you can do a continuity test on the cable ... tough but doable with some small pins on the probes or otherwise.

One other point... have you checked any other input types?

Good idea on testing the cable. I will do that tonight. I have not tried any other inputs if not simply because I am not getting a menu or anything.

I'll try the other HDMI inputs. Idea being that perhaps they may show even more of a picture or something?

[scuby]

Re: Bad driver(s)? Sharp LED TV

Are you getting about 12 volts on each side of the fuse on the tcon, red probe on each side black probe on metal chassis.

I can't locate a fuse... looking for a standard cylindrical fuse yes?

[budwich]

Re: Bad driver(s)? Sharp LED TV

they are usually "micro fuses" that are "smd'ed" to the board. ***** added ***** there appears to be one fuse in the corner at p4804 connector which I assume comes from the power board.... its a larger SMD component between two "islands"... but that's just a guess. You can likely trace that connector back somewhere to power if need be. *******

You might do a "trace" of 12v at the power board to the main board and then to the tcon.

I think I watched your video of the set that you posted. I am thinking the problem is more with the main than the tcon... but maybe cabling especially since the 2 tcons work differently. Are you sure that you are seating the lvds cables between the main and tcon well / correctly?


I see tracing could be tough as this "fzcxvz" company decided to save money on label paint ... :-(

[budwich]

Re: Bad driver(s)? Sharp LED TV

you might try "slight heating" (hair dryer) on the mediatek chip on the main board to see if anything happens / changes... even subtly. A "quick look" appears to shows that the lvds signals basically leave that chip thru some "buffers" to the cable.... if my "inexperienced eyes" are correct.

[scuby]

Re: Bad driver(s)? Sharp LED TV

My walk through of what I've done so far

[scuby]

Re: Bad driver(s)? Sharp LED TV

they are usually "micro fuses" that are "smd'ed" to the board. ***** added ***** there appears to be one fuse in the corner at p4804 connector which I assume comes from the power board.... its a larger SMD component between two "islands"... but that's just a guess. You can likely trace that connector back somewhere to power if need be. *******

You might do a "trace" of 12v at the power board to the main board and then to the tcon.

I think I watched your video of the set that you posted. I am thinking the problem is more with the main than the tcon... but maybe cabling especially since the 2 tcons work differently. Are you sure that you are seating the lvds cables between the main and tcon well / correctly?


I see tracing could be tough as this "fzcxvz" company decided to save money on label paint ... :-(

Ok. Once the kids are in bed I'll check the LVDS for breaks/continuity.

I'm as sure as I can be that I'm seating that cable correctly. Also since removing it and reseating it the symptoms are all the same as before I touched it.

[scuby]

Re: Bad driver(s)? Sharp LED TV

you might try "slight heating" (hair dryer) on the mediatek chip on the main board to see if anything happens / changes... even subtly. A "quick look" appears to shows that the lvds signals basically leave that chip thru some "buffers" to the cable.... if my "inexperienced eyes" are correct.

I'll give that a shot. There's a chip labelled: Pixel works Motion Engine which looks to run to the LVDS. I'll heat that. and observe.

I'll see if I can't find that fuse...