Panasonic VIERA TC-L32X5 - One LED blink

[WannaTheater]

Hi all- First post here. I have a Panasonic TC-L32X5 TV, that is doing the following:

- Right half of screen is dark, "HDMI 1" is displayed, "No Signal" is displayed, then TV turns off, with the RED LED blinking on and off repeating (1 blink per repeat)

With the back off, it looks like the following is happening inside the panel when the TV is turned on:
1) Entire panel lights up (white LEDs? inside the metal casing, that I can see through holes)
2) Right side goes dark
3) Entire panel lights up a second time
4) Right side goes dark
5) Entire panel lights up a third time
6) Right side goes dark
7) TV shuts itself off

From the service manual I found online, there are 3 boards - P Board (Power and LED driver), A Board, and K board (Remote, LED, Luminance Sensor).

Also per manual, one blink equates to:
BL_SOS - SOS from PANEL inverter. I am not sure if this is saying the panel is bad, or there is an inverter circuit that feeds the panel that is bad (perhaps on the P board?).

I am capable of swapping boards, and there are a few identical P boards on eBay. I'm alse experienced with testing boards (voltages, diodes, etc), although I don't have a scope. I have the proper equipment to replace components. But I am just not familiar with the circuitry in these TVs.

Any suggestions on where to look/try next?
Or does this thing need to take a trip to the curb on garbage day?

[WannaTheater]

Re: Panasonic VIERA TC-L32X5 - One LED blink

I should also add that this TV was working fine about 6 months ago. I recently put a bracket on the back (VESA), mounted it on a wall, turned it on to find it didn't work. Not sure if it stopped working because it sat for a while without turning it on, or if hanging it up perhaps shifted the case on the back??/ (just guessing here now)

[dick_barton]

Re: Panasonic VIERA TC-L32X5 - One LED blink

Can you post some picture. Did the screws that you used to wall mount it cut into any cables / circuit board?

[WannaTheater]

Re: Panasonic VIERA TC-L32X5 - One LED blink

I will try to get some pictures, but inside looks brand new. No screws pierced anything, nothing burned, very clean. TV was purchased in around 2012 or 2013, with minimal use.

I just managed to get the self-test to run, and it shows everything OK.
(everything on the remote and menu seems to works fine, but I have to do things fast.. I only get about five seconds after turning the TV on before it shuts down). Then I have to unplug, plug back in, and start again.

[diif]

Re: Panasonic VIERA TC-L32X5 - One LED blink

So the TV worked until you hung it on the wall ?
Not the first time i would have seen a TV damaged from using screws that are too long in the VESA mount or stand.
As Dick says, take the back off and post some photos.

[WannaTheater]

Re: Panasonic VIERA TC-L32X5 - One LED blink

Diif- I cannot be positive that the two are related. I had not turned the TV on in 6 months. I should have tested it before I hung it up-

[WannaTheater]

Re: Panasonic VIERA TC-L32X5 - One LED blink

Just checked- There is no way for the VESA mount screws to do any damage- They have their own mounting holes on the chassis, and are inches from any electronics or cables.

[WannaTheater]

Re: Panasonic VIERA TC-L32X5 - One LED blink

Here is a link to 4 photos. The fourth shows how the the right half is dark. From the self-test, it looks like it reset the TV back to factory. Note, I took this photo right before the TV turned itself off.

https://get.google.com/albumarchive/...OjemaHg_fzArQE

Let me know if you cannot see the photos-

[dick_barton]

Re: Panasonic VIERA TC-L32X5 - One LED blink

I wonder if you have led(s) failing. Can you measure the voltages on the pins of the connector going to the leds. Looks like it uses edge lit leds.

[WannaTheater]

Re: Panasonic VIERA TC-L32X5 - One LED blink

What is odd is that the all the LEDs light up initially, then one side shuts down, then they all light up again, then one side shuts down, etc. This makes me think it is not the LEDs, but the circuit driving them- I assume that when an LED fails... It FAILS completely (i.e. won't come on). It is also odd that the TV is shutting off. Much of what I have seen with LEDs failing is that the TV stays on-

I will try to measure voltages if possible-

Also, my assumptions may be wrong!

[dick_barton]

Re: Panasonic VIERA TC-L32X5 - One LED blink

What is odd is that the all the LEDs light up initially, then one side shuts down, then they all light up again, then one side shuts down, etc. This makes me think it is not the LEDs, but the circuit driving them- I assume that when an LED fails... It FAILS completely (i.e. won't come on). It is also odd that the TV is shutting off. Much of what I have seen with LEDs failing is that the TV stays on-

I will try to measure voltages if possible-

Also, my assumptions may be wrong!

When the leds light they heat up and then can fail and this just repeats. Whether or not the TV shuts down is dependant on how the set is programmed.

Also if it's been in the garage for months and you have any moisture, it could be that the connector to the led strip has some corrosion on it and needs cleaning.

[WannaTheater]

Re: Panasonic VIERA TC-L32X5 - One LED blink

Ahh. Thanks. Odd question- Should I swap the two cables to see if the problem follows the cables?

[dick_barton]

Re: Panasonic VIERA TC-L32X5 - One LED blink

That would be the quickest test.

[WannaTheater]

Re: Panasonic VIERA TC-L32X5 - One LED blink

Unless I swap the wires in the header, I cannot easily switch them (I have not disassembled the panel).

When measured to chassis ground:
Pin 3 (LED1) is 46Vdc
Pin 6 (LED4) starts at 46Vdc then drops to 1V quickly

LED2 and LED3 are not connected.

When I disconnect the panel from the Power supply board, both pins 3 and 6 are +5Vdc.

[WannaTheater]

Re: Panasonic VIERA TC-L32X5 - One LED blink

Continuing to experiment:

1) I swapped the two pairs of wires in the header- No difference
2) With the LED header disconnected, the TV still cycles through and shuts itself down, leaving the 1 blink red LED
3) I have tried with one pair disconnected, and then the other. TV still shuts down.

If the TV is still shutting down while the LEDS are disconnected, wouldn't that imply there is another protection shutting it down?
I am unsure of what the panel inverter is (per 1 blink code).

[tw2005]

Re: Panasonic VIERA TC-L32X5 - One LED blink

Continuing to experiment:

1) I swapped the two pairs of wires in the header- No difference
2) With the LED header disconnected, the TV still cycles through and shuts itself down, leaving the 1 blink red LED
3) I have tried with one pair disconnected, and then the other. TV still shuts down.

If the TV is still shutting down while the LEDS are disconnected, wouldn't that imply there is another protection shutting it down?
I am unsure of what the panel inverter is (per 1 blink code).

You'll probably find a number of individual LEDs have failed or maybe shorted enough for the cct to detect and shutdown which would explain how it lights up and then turns off.

You're probably not going to detect this or see unless the panel is disassembled or if someone knows hoe to meter it to spot a difference.

Disconnecting is simply just going to present an open cct which the controller board I'd expect to recognise as a fault too.

[WannaTheater]

Re: Panasonic VIERA TC-L32X5 - One LED blink

After disassembling the panel, here is what I found:
- There are two LED strips at the bottom of the TV- One for the right half, one for the left half.
- When the TV is powered on, they both turn on. Then the left one turns off (the whole strip). This repeats twice more, then the TV turns off.

[tw2005]

Re: Panasonic VIERA TC-L32X5 - One LED blink

After disassembling the panel, here is what I found:
- There are two LED strips at the bottom of the TV- One for the right half, one for the left half.
- When the TV is powered on, they both turn on. Then the left one turns off (the whole strip). This repeats twice more, then the TV turns off.

So what are you saying? There is only a single line of leds at the bottom illuminating the panel?


Maybe double check all LEDs are lighting, I know when I did a 50" at first glance it looked like they were but it multiple strips and I think 2 leds were out and that was enough to shut that TV down. I did not pick them at first the light was so bright.

sorry if I lead you astray

[attainteddragon]

Re: Panasonic VIERA TC-L32X5 - One LED blink

i normally film it as they light and then go out, then play it back frame by frame to identify bad led's.

[WannaTheater]

Re: Panasonic VIERA TC-L32X5 - One LED blink

Yes- There are two LED strips running along bottom.

Additional photo attached:
https://get.google.com/albumarchive/...OjemaHg_fzArQE


I took video, slowed it down, and although it is difficult to be 100% sure (due to brightness), I do not see any LEDs out.

At this point, I am about 85% sure this TV is going to the trash