Riddled TV Repair Forum

rbudrick · Joined: 23 Mar 2018 Posts: 10 Location: NH

Hi Folks,

As per the title, this TV just stopped showing anything onscreen, including menus. It's a black screen, but the backlight is on. Many sites have people complaining of the same issue, and they all recommend almost the same non-working solutions:

1. Unplug the TV for a few minutes. Hold the power button for up to 30 seconds to discharge. Neither work, even leaving it unplugged for days.

2. Replace the TCon board.

The problem is there is no Tcon in this set. There's a power board, a tuner board and a main board. I have replaced all three without change. There also appears to be two inverter boards (I'm assuming...they are long and skinny and joined by a flat ribbon cable), but since I have backlight, I ruled them out.

This happened last year and after taking the set apart with no obvious fix, I put it back together and it just started working again. It'd been fine since, except the issue started up again and now won't resolve.

I'm totally stumped on this,, Hope you can help! Could the LCD Panel itself have failed? Where would I even buy that? I see nothing on eBay.

Thanks Very much!v
Yours,
Rob

Google

JTS1957 · Joined: 21 Jan 2009 Posts: 2395 Location: Far, Far Away

Tcon should be at other end of Flat Flexible Cable (FFC). Part of Panel.

rbudrick · Joined: 23 Mar 2018 Posts: 10 Location: NH

OK, I see. Thanks for the reply and sorry for delay in getting back.

I thought the board you referenced was an inverter board because it was so long and thin, as inverters usually are (flat ribbon connects to one long skinny board, and that one connects to another board by another short ribbon. Both attach directly to the LCD. Is this really the TCON? If it is, there are no inverter boards in this set...are there sets now without those? ). The double-board, for lack of a better term, does not appear to be user-replaceable, as it connects to the LCD via those ribbon cables that are not user-serviceable. Pics:

https://www.dropbox.com/s/p9jk3ombpipoeiq/20180325_145430.jpg?dl=0
https://www.dropbox.com/s/vn77lvlc8xpiun9/20180325_145335.jpg?dl=0
https://www.dropbox.com/s/j0fsmna8eptnd7h/20180325_145311.jpg?dl=0
https://www.dropbox.com/s/2few2emac4391ek/20180325_145255.jpg?dl=0
https://www.dropbox.com/s/9zv6w52pdjbjgyq/20180325_145243.jpg?dl=0
https://www.dropbox.com/s/i0eo5dums4iekzl/20180325_145023.jpg?dl=0
https://www.dropbox.com/s/nwt96tea6pkv9d8/20180325_145357.jpg?dl=0
https://www.dropbox.com/s/pqm2lapk4xt4hot/20180325_145216.jpg?dl=0
https://www.dropbox.com/s/ldqdufs96zmm7kp/20180325_145157.jpg?dl=0

EDIT: Sorry, I tried to get these to show as images, but they don't work when adding the img tags.

Edit 2. Googling the model numbers seem to indicate this is known as a matrix board and not the TLG. So, does my set have no TLG and no inverter boards?

Thanks again!

JTS1957 · Joined: 21 Jan 2009 Posts: 2395 Location: Far, Far Away

Backlight Type: LED
NO inverter boards.
Yes that is the tcon (only replaceable by replacing the whole panel).

You could see if the surface-mount fuse to the right of where ribbon connects in last picture is good and has 12 volts on both sides of it.

rbudrick · Joined: 23 Mar 2018 Posts: 10 Location: NH

OK, thanks! Would a simple continuity test tell me the same, being a fuse and all? Just trying to avoid a shortage if doing it while powered.

Thanks again!

-Rob

Google

JTS1957 · Joined: 21 Jan 2009 Posts: 2395 Location: Far, Far Away

Say the fuse is good, How do you know if 12 volts is reaching the Tcon?

rbudrick · Joined: 23 Mar 2018 Posts: 10 Location: NH

rbudrick · Joined: 23 Mar 2018 Posts: 10 Location: NH

Well, there's some news, on double checking. The fuse was visible and easily accessible to the probes of my multimeter, as there was a gap in the shielding next to the ribbon. The fuse has continuity, but when I set the meter to the up-to 20 volts direct setting, the negative probe to ground (at the power port), and the positive probe to either side of the fuse, I get absolutely nothing, even though the ribbon has continuity on every pin from the main board to the TCON. I assume the ribbon is where power comes into the TCON, because besides the ribbons that lead to the lcd, there's no other cables to supply it that I see.

Any ideas? Or am I pretty much out of luck?

Thanks again!

rbudrick · Joined: 23 Mar 2018 Posts: 10 Location: NH

OK, I made a dumb rookie move. The TV was only on standby when I tested the fuse. I powered the TV to on and the fuse does indeed get +12.

JTS1957 · Joined: 21 Jan 2009 Posts: 2395 Location: Far, Far Away

https://imgur.com/nD40oNJ