Sharp LC-60C6400U Only Backlight

[jason123]

Hi folks,
Question of whether it's a Main card or TCON for this TV. Power comes on, and only the backlight comes on. Main board is responsive to on /off, and power is coming on the TCON. I checked few voltages on the TCON, and I get the 3.3, 34.xV 7.5V, 11.97 V (though only 11.97 is coming from the main board when the TV is on. No flashing error codes.
Photos attached.. what's next in determining which board is the issue?

One thing to note, is the Optical red light doesn't come on (Main board) when the TV turns on. I thought they all have that port on upon bootup.

[budm]

Re: Sharp LC-60C6400U Only Backlight

"I checked few voltages on the TCON, and I get the 3.3, 34.xV 7.5V, 11.97 V (though only 11.97 is coming from the main board when the TV is on." Please clarify as to the names of those Voltages on the T-CON board.
What happen if you have one cable between T-CON and the LCD panel connected one at a time?

[jason123]

Re: Sharp LC-60C6400U Only Backlight

budm, the voltages are not labeled on the TCON - I was simply spot-checking the large caps by the switching power supplies.

Disconnecting the cables from TCON to Panel one at a time, results in the disconnected side being white, and the other side black. Disconnecting both, results in left hand side (as you're facing the TV) being white, and the right hand side having horizontal bands
I can take photo of the last case if needed.

[jason123]

Re: Sharp LC-60C6400U Only Backlight

Any opinions on this budm?

[budm]

Re: Sharp LC-60C6400U Only Backlight

I expect to see minus supply Voltage on the T-CON board too, but without test points then it will be hard but one thing you can do is to look up spec. sheet for the LCD power supply IC to see if it is putting out the Voltages or not.

[jason123]

Re: Sharp LC-60C6400U Only Backlight

I do see a -5 V generated on the board. Basically every cap has some "seemly" regulated voltage on it. Does that point to Main board?

[budm]

Re: Sharp LC-60C6400U Only Backlight

I do see a -5 V generated on the board. Basically every cap has some "seemly" regulated voltage on it. Does that point to Main board?

May be, due to the fact that you do not see red light inside the TOSLINK port. But if the T-CON board has low price then I would try T-CON board first.

[jason123]

Re: Sharp LC-60C6400U Only Backlight

Tcon is about $30, vs over $100 for the Main board

One additional question though if anyone knows.. ShopJimmy lists several boards as compatible main boards, but there is a note that says:
Important Message: !!! IMPORTANT--PLEASE NOTE !!! It's likely that this board needs to be configured to work with your specific TV model after installation. Without performing this step, the board will likely appear defective or the picture on the screen will be the wrong size. The instructions for this process are included with the board upon shipment.

And:
FIRMWARE UPDATE MAY BE REQUIRED UPON INSTALLATION FOR BOARD TO FUNCTION CORRECTLY. Visit http://www.sharpusa.com/Support.aspx to download the latest firmware for the specific model of your TV.

Given that I don't get a picture - Is there a way to try flashing the main board? looks like the instructions require some interactions with visual software and without that - is there a failsafe method to update firmware??
Thanks

[budwich]

Re: Sharp LC-60C6400U Only Backlight

budm, the voltages are not labeled on the TCON - I was simply spot-checking the large caps by the switching power supplies.

Disconnecting the cables from TCON to Panel one at a time, results in the disconnected side being white, and the other side black. Disconnecting both, results in left hand side (as you're facing the TV) being white, and the right hand side having horizontal bands
I can take photo of the last case if needed.

pictures probably won't help but can't hurt either. It is strange that you get "lines" when the panel has no connections go to it.

The reactions with the "one cable disconnected" appear to be normal but again pictures would help as potentially your eye and the forum's eyes aren't the same... you don't see what you don't need to see... :-)

In terms of "the voltages are not labeled on the TCON - I was simply spot-checking the large caps by the switching power supplies"... this refers to checks at the power supply not the tcon, right? You should be able to do some "visual tracing" on wiring / voltage pins from one board to another to get some idea of things... maybe. Since there are no direct wires from the power supply to the tcon, that means that main board is swtiching / controlling voltages to the tcon. You should be able to find some points / pins of interest... again via tracing... with your eyes or a meter (not under power... using resistance / continuity checks).

you need to provide a "chart" of the power board pin labelling (they are labelled) and measurements.... ie pin number, measurement. Do this for "standby" and also for "power on / turn on".

[jason123]

Re: Sharp LC-60C6400U Only Backlight

So the spot checking i was doing is on the TCOn not power supply. Tcon is only powered by main board (or through main board). Tcon gets 11.8v or so when the set is turned on. It generates its own rails, it seems, on the TCON. I can provide the photos .. just wanted to clarify some confusion

[budm]

Re: Sharp LC-60C6400U Only Backlight

Are you able to get the IC P/N for the LCD power supplies?

[budwich]

Re: Sharp LC-60C6400U Only Backlight

So the spot checking i was doing is on the TCOn not power supply. Tcon is only powered by main board (or through main board). Tcon gets 11.8v or so when the set is turned on. It generates its own rails, it seems, on the TCON. I can provide the photos .. just wanted to clarify some confusion

ok... thanks. Then the next question is... did you check for labeling on the bottom edge boards going to the panel?

[jason123]

Re: Sharp LC-60C6400U Only Backlight

Are you able to get the IC P/N for the LCD power supplies?

Yes, but I can't find datasheets for them - I believe Rohm parts
DB8124 and BD8100

[jason123]

Re: Sharp LC-60C6400U Only Backlight

ok... thanks. Then the next question is... did you check for labeling on the bottom edge boards going to the panel?

Nothing that I can see budwich

[nomoresonys]

Re: Sharp LC-60C6400U Only Backlight

For tcon, shopjimmy says to look for 01 or 08 on your sticker heres 08 list: https://www.ebay.com/sch/i.html?_fro...=DUNTKF975FM01

[nomoresonys]

Re: Sharp LC-60C6400U Only Backlight

01 list: https://www.ebay.com/sch/i.html?_fro...=DUNTKF975FM01

[budwich]

Re: Sharp LC-60C6400U Only Backlight

Nothing that I can see budwich

Those are not "edge boards". The boards that you are showing are boards that connect to the edge boards. There are boards, long and narrow that connect the panel to the system. There is usually labeling there... of course, there is usually labeling else where which this set makeup doesn't have either ... but again, any helpful info that can be found may better pin point the issue.

Your "tcon cable disconnect tests" appear to indicate either an signalling issue (video stream not there) and / or panel powering issue (which could be a problem at the edge board or tcon).

can you please post pictures of the "tcon cable disconnect test" displays?

[jason123]

Re: Sharp LC-60C6400U Only Backlight

Those are not "edge boards". The boards that you are showing are boards that connect to the edge boards. There are boards, long and narrow that connect the panel to the system. There is usually labeling there... of course, there is usually labeling else where which this set makeup doesn't have either ... but again, any helpful info that can be found may better pin point the issue.

Your "tcon cable disconnect tests" appear to indicate either an signalling issue (video stream not there) and / or panel powering issue (which could be a problem at the edge board or tcon).

can you please post pictures of the "tcon cable disconnect test" displays?

Sorry, misread what you're asking - thought you wanted to see if there are any labels on the edge of the boards (TCON) I don't see much of the "edge boards" assembled, so I have to disassemble the panel to access the edge-boards. I can do that if needed
here are photos of the ribbon cable tests. With both disconnected, is not consistent, depending on the sequence. If I disconnect left, then reconnect and disconnect right, then disconnect both It seems to retain the last state and shows "right" white. If I have them both connected, then disconnect both, I get no white, just backlight. Sorry photos are half-cropped as I'm holding TV one hand and taking photo with the other (no stand)

[budwich]

Re: Sharp LC-60C6400U Only Backlight

thanks... good "juggling"... :-)

I think that your earlier "observation" about the horizontal lines appearing when both sides were disconnected was some what "confusing" as it is hard to understand how no connection to a panel can make it display something... but you appear to have provided a bit more "insight" as to how the result occurs.... maybe although now you don't mention anything about lines.

OK... I now see some form of horizontal lines... actually look like bands... almost like ground loop "hum"... contained within the white sides. In a "normal display response", there should be a "clean / uniform white" especially since nothing is being fed to the one side to cause anything to happening at the vertical drivers.

In my limited understanding, with nothing connected, I am not sure how a panel can provide anything but black... but maybe "memory" occurs in the lcd... although that doesn't sound quite right / good.

I hope that you are depowering before you do any cable changes... right?

[jason123]

Re: Sharp LC-60C6400U Only Backlight

Yes, I am depowering. and, the actual TV doesn't have these bars - it's clean uniform white. I think this is my camera problem.