Panasonic Viera LED TH60CX700A - Sound / Backlights Working - No Picture

[Frost3h]

Hi Everyone,

Looking for a little advice.

I acquired a 60" Panasonic LED (TH-60CX700A) a few months ago and have been idly trying to fix it. I got told it had no picture yet backlights and sound were still working, my testing confirmed this so it looked like a simple TCON replacement would solve the issue.

Obtained a new TCON board (LC600EQF-PHF1-8A1) and installed with the same results. I figured at this point the TCON wasn't being supplied with a video signal (TV shows up on a laptop when I connect a HDMI and I'm able to get sound out) so I replaced the LVDS cables and the mainboard. Still no picture. I've tried disconnecting one half of the cables going to the tcon (both the 41pin and the 51 pin) while leaving the other side plugged in but no picture is displayed. If I disconnect both tcon cables the TV will cycle through primary colours until powered off.

I've read over the documentation provided in BudM's LCD TV and Monitor basic troubleshooting guides and quoting from the documentation I'm assuming this is the issue:

"Logic board supplies 5 or 12vdc to T-CON board B+ pin through switched transistor if T-CON board does not get the voltage from the logic board, you will get white/gray glowing screen without pictures."

If I power on the TV and use the remote, the backlight changes as if it was adapting to what is supposed to be shown on screen so this part seems to be functioning as intended.

So now I'm looking at the power to the mainboard / tcon as being the issue, I'm slightly amiss as to where to go from here though, I'm an IT tech by trade so I'm comfortable swapping out boards and cables without much issue, my electronics skills are very VERY lacking but at this stage I'd be ever so grateful if someone can provide some direction. I've got a multimeter and can test if pointed in the right direction. At this point I'm thinking the issue is with Power board A which has the white cable running to the mainboard)

I've looked at the power boards feeding the mainboard and I can't see any bulging caps or discoloured parts, but a more trained eye might be able to spot something.

Any help is greatly appreciated!

TH-60CX700A
Part numbers:
Mainboard: TNPH11202A
TCON: LC600EQF-PHF1-8A1
Power board A: TNPA6060DC
Power board B: TNPA6074FR

Photos attached of all the boards.
Edit: Apparently being from Australia means all your images upload upside down or something, fixed now, apologies.

Thankyou!

[Frost3h]

Re: Panasonic Viera LED TH60CX700A - Sound / Backlights Working - No Picture

Hey guys,

Shameless bump.

I've now swapped out the power board (TNPA6060DC) with no luck.

Any suggestions on where to troubleshoot next or even telling me the panel is dead would be greatly appreciated.

If I attempt to put the TV in test pattern mode (volume down + 3 yellow button on the remote) it begins its colour flash and cycle pattern.

Thanks everyone.

[vinceroger69]

Re: Panasonic Viera LED TH60CX700A - Sound / Backlights Working - No Picture

have you confirmed you have voltage to both sides of the fuse on the tcon board? (top right under connector white oblong fuse)

[Frost3h]

Re: Panasonic Viera LED TH60CX700A - Sound / Backlights Working - No Picture

have you confirmed you have voltage to both sides of the fuse on the tcon board? (top right under connector white oblong fuse)

Hey mate,

Just checked it then, 12v on either side of the fuse.

[diif]

Re: Panasonic Viera LED TH60CX700A - Sound / Backlights Working - No Picture

Top left in your t-con photo. There looks to be a ceramic cap not right ?

[Frost3h]

Re: Panasonic Viera LED TH60CX700A - Sound / Backlights Working - No Picture

Top left in your t-con photo. There looks to be a ceramic cap not right ?

Looks like that one is definitely damaged. It's refreshing to know I've missed things as this has been driving me a bit spare for a while now

I've attached an image of the replacement TCon I swapped over to (same issue with no picture coming through)

[diif]

Re: Panasonic Viera LED TH60CX700A - Sound / Backlights Working - No Picture

And you've checked the voltage on both sides of the fuse on the replaced t-con ?

[flocko]

Re: Panasonic Viera LED TH60CX700A - Sound / Backlights Working - No Picture

the part number showing on the first T.con is 4075A the replacement shows 3987A , have you checked that this is a compatible T.Con replacement?

[Frost3h]

Re: Panasonic Viera LED TH60CX700A - Sound / Backlights Working - No Picture

And you've checked the voltage on both sides of the fuse on the replaced t-con ?

Confirmed 12V on either side of the replacement

the part number showing on the first T.con is 4075A the replacement shows 3987A , have you checked that this is a compatible T.Con replacement?

That part I regret to say I glossed over unfortunately

In terms of repairing the original tcon, how could I go about figuring out what the values of the ceramic cap that was damaged was?

[diif]

Re: Panasonic Viera LED TH60CX700A - Sound / Backlights Working - No Picture

The ceramic cap looks to have broken off and slipped diagonally ?
Can't tell from the photo how bad the damage is but you could try and solder it back or measure the cap on your other t-con.

[flocko]

Re: Panasonic Viera LED TH60CX700A - Sound / Backlights Working - No Picture

The only hope you have is to find the correct T.Con . you could have caused damage to the main board or screen drivers by fitting the incorrect board, as this set uses the LG panel with a Panasonic main board the T,Con also acts to interface the two, so you would need a working 6871L-4057A to reference the components, and if you had that and your set worked there would be no need for repair

[Frost3h]

Re: Panasonic Viera LED TH60CX700A - Sound / Backlights Working - No Picture

The only hope you have is to find the correct T.Con . you could have caused damage to the main board or screen drivers by fitting the incorrect board, as this set uses the LG panel with a Panasonic main board the T,Con also acts to interface the two, so you would need a working 6871L-4057A to reference the components, and if you had that and your set worked there would be no need for repair

Hey Flocko / diif,

Thanks for the advice. I incorrectly assumed because I had the model correct that would have been all I needed. Combination of arrogance and naivety.

I've located a replacement tcon with the correct part number and model and its on its way.

I'll see if that cap that has dislodged can be reattached but my soldering skills aren't that precise.

With any luck I haven't damaged anything irreparably, if I have, this will be an expensive lesson but a lesson all the same.

I'll update with what happens when the replacement TCON arrives.

Thanks for all the advice and I appreciate the time you all took!

[webpanther]

Re: Panasonic Viera LED TH60CX700A - Sound / Backlights Working - No Picture

Did you ever solve this?
I am looking for the same T-Con board, 6871L-4057A.
Cannot find one anywhere on the internet.

[hoangmai]

Re: Panasonic Viera LED TH60CX700A - Sound / Backlights Working - No Picture

Hi webpanther,
I found the T-Con board you are looking for on NarayaniTech in India.
You can Google that name.
Good Luck.

[xaviche]

Re: Panasonic Viera LED TH60CX700A - Sound / Backlights Working - No Picture

Hi !
Sorry for the up, but I got the same problem on a Panasonic TX-55CX680E.
I bought a new t-con card, but the trouble is still there. I checked the fuse on the t-con card, check that the 12V goes out of the motherboard and it's ok.
So I'm asking if someone has the answer, especially if Frost3h fix his TV.

Thanks all

[budm]

Re: Panasonic Viera LED TH60CX700A - Sound / Backlights Working - No Picture

Hi !
Sorry for the up, but I got the same problem on a Panasonic TX-55CX680E.
I bought a new t-con card, but the trouble is still there. I checked the fuse on the t-con card, check that the 12V goes out of the motherboard and it's ok.
So I'm asking if someone has the answer, especially if Frost3h fix his TV.

Thanks all

https://www.badcaps.net/forum/attach...1&d=1484132385
So if you only have one cable (white flat cables) between T-CON and the LCD panel connected one at a time, what do you see on the screen?

[Acerman]

Re: Panasonic Viera LED TH60CX700A - Sound / Backlights Working - No Picture

I have a very similar problem with a Panasonic TX50DX700b model. I am struggling to find the cause of the blank screen . Audio comes through and you can change channels with the remote but the screen has a blue hue and not even a ‘no signal' message. Backlights are clearly working as you can see them brightly lit at the rear of the panel. I have checked the tcon fuse and the 12 volts is present. I also fitted a working replacement tcon board with no effect. I have changed the main board for a known working one from a donor TV. Still the same.
When I disconnect the right side tcon ribbon (rear panel side up) the opposite side half of the screen goes bright white. When I disconnect the left side tcon ribbon the screen is completely blue just as with both tcon ribbons connected.
My theory is that there is an issue with the right side led driver board. Perhaps a bad smd capacitor. Not sure though. Any help would be appreciated.

[nomoresonys]

Re: Panasonic Viera LED TH60CX700A - Sound / Backlights Working - No Picture

Check those MLCC caps for low ohms, expect over 100 ohms on those when testing with meter set to 200 ohms.

[dandan556]

Re: Panasonic Viera LED TH60CX700A - Sound / Backlights Working - No Picture

I have a very similar problem with a Panasonic TX50DX700b model. I am struggling to find the cause of the blank screen . Audio comes through and you can change channels with the remote but the screen has a blue hue and not even a ‘no signal' message. Backlights are clearly working as you can see them brightly lit at the rear of the panel. I have checked the tcon fuse and the 12 volts is present. I also fitted a working replacement tcon board with no effect. I have changed the main board for a known working one from a donor TV. Still the same.
When I disconnect the right side tcon ribbon (rear panel side up) the opposite side half of the screen goes bright white. When I disconnect the left side tcon ribbon the screen is completely blue just as with both tcon ribbons connected.
My theory is that there is an issue with the right side led driver board. Perhaps a bad smd capacitor. Not sure though. Any help would be appreciated.

Hi, found this post via Google, I have the same model TV with the EXACT same issue, did you ever find the cause of this?

[budm]

Re: Panasonic Viera LED TH60CX700A - Sound / Backlights Working - No Picture

Hi, found this post via Google, I have the same model TV with the EXACT same issue, did you ever find the cause of this?

1) So you get the same result when one cable between T-CON and the LCD panel is connected one at time and you do have 12V at both ends of the T-con fuse, correct?
2) If the above is true then you need to check the resistance of the MLCC on the tab bonding boards as suggested. ACEMAN never posts back what he found.