Panasonic TC-55CX400U - stuck on logo

[g20zoom]

Sad to say...after 1 year, this TV is no stuck on the "PANASONIC" logo screen upon power up.

Is there any hope for saving this? Is there some kind of hard reset I can do or does it need some kind of new board?

Thanks

[tw2005]

Re: Panasonic TC-55CX400U - stuck on logo

1 year old? Contact Panasonic , surely they can help under warranty.

[tom66]

Re: Panasonic TC-55CX400U - stuck on logo

Argh! Another "Not Panasonic" sold as a Panasonic.

You are unfortunately a victim of Panasonic rebadging cheap sets as their own to cut costs. You will almost certainly find the issue is cheap NAND flash memory which has failed. Replacing the main board is likely to fix the issue.

I can't be certain, but this should be compatible. Have a look around for other sets as well.
https://www.ebay.com/i/322765368785?rt=nc

I am assuming your set is powering onto the logo and staying on that. If so, then it is the main board crashing as it tries to boot the rest of the software. Corrupted NAND flash, due to the use of very cheap flash memory devices, is causing the set to die in the middle of the boot-up process. These TVs are embedded computers, and they usually run Linux of one form or another.

[g20zoom]

Re: Panasonic TC-55CX400U - stuck on logo

My dad went cheapie with this brand. It's over 1 year so no more warranty. He even paid for a service call a year ago, but never told me about it so I have no idea what they diagnosed. Frustrating but he's pretty old now. He bought it from Fry's but lost the receipt, and being such a pain to get it again, then use the credit card maybe for the 2nd year of warranty, I figure I'll just troubleshoot myself!

More details:
Upon power up, the "Panasonic" logo is displayed, then the unit powers off within 2-3 minutes.

I looked at the power supply, and no caps are blown. I can't really tell if any of the caps are raised beyond normal. Hard to say.

I checked the voltages on the PSU.
I got around 5V on the +5VSB line to ground.
I then connection PSON with the +5VSB line.
I measured 3 other 5V lines, 2 - 12V lines, and in another block, 2 - 24V lines.

So you think it's the main board? Well I realized it is powering onto the logo, but then shutting down in a few minutes. So I'm not sure is that still pointing to the corrupted NAND flash?

ebay does have a couple of the mainboards for sale using model # so it seems like I have a way out, until the next one dies assuming it's still the board.

[ducky29]

Re: Panasonic TC-55CX400U - stuck on logo

It might be a firmware problem.

Here is the firmware
ftp://54.165.229.211/television/soft...u_firmware.zip

and the instructions

[g20zoom]

Re: Panasonic TC-55CX400U - stuck on logo

ducky29,

Thanks for the firmware.
I powered it up per the instructions with the bin on the USB stick, and it upgraded the firmware, powered off.
Then it powered up, upgraded firmware again, powered off.
Repeated again for a 3rd time.
At this point, I just put the tv face down as I have the back cover off.

What do you think is going on? Sounds like it's not upgrading but then not sticking to the board.
I would think if the firmware was really updated, the firmware would be smart enough to not load the same version again. But if the firmware never saves, then maybe there is a mainboard issue?

[g20zoom]

Re: Panasonic TC-55CX400U - stuck on logo

tom66 or anyone else that knows...

My main board is stamped "CV6488H-A".
There is also C/N: 890-M00-06NBZ

Since this is rebadged...this board can be bought as a Westinghouse, Elements, or Panasonic. Do you know if it's ok to use any brand? Or will the specific firmware mess things up?

Also, someone on ebay does have the same board but it's for the Panasonic 50 inch version. ie TC-50CX400U
Can I use this board and maybe just reload the firmware?

Thanks

[dskall]

Re: Panasonic TC-55CX400U - stuck on logo

If boards are the same then they should work but you will probably have to change remotes.

[tom66]

Re: Panasonic TC-55CX400U - stuck on logo

My dad went cheapie with this brand. It's over 1 year so no more warranty. He even paid for a service call a year ago, but never told me about it so I have no idea what they diagnosed. Frustrating but he's pretty old now. He bought it from Fry's but lost the receipt, and being such a pain to get it again, then use the credit card maybe for the 2nd year of warranty, I figure I'll just troubleshoot myself!

This is the pain, Panasonic normally makes good products, and up until recently did not rebrand anything! So you cannot blame your dad for picking up what is ostensibly a Panasonic television knowing that they normally make very high quality sets.

They seem to have tried it recently in the UK and the US with these cheap TVs - probably so they can be more competitive - but they have discovered what Sharp's pain was when they did this, which is that customers lose trust in your brand, and this long term loss is far better than the short term gain of selling a few more TVs a little cheaper.

Since this is rebadged...this board can be bought as a Westinghouse, Elements, or Panasonic. Do you know if it's ok to use any brand? Or will the specific firmware mess things up?

It should be okay - but the brand will appear differently when the set powers up. This shouldn't be a problem. Some settings and options may be different. It is likely that all the sets are made with the same panel, but it is possible they are not, if so, you may have some compatibility issues with the image on the screen. If this occurs, you will need to return the board until you find a compatible version (make sure you order from a company that supports returns.) Most of these cheapie sets use the same panels so you should be okay here. As dskall says there's a chance the remote will be different as well.

[g20zoom]

Re: Panasonic TC-55CX400U - stuck on logo

Thanks guys for all the tips. It's amazing what you can learn from here.
That's true...we had many great Panasonic things in the 80s and 90s from them. Shame they are cutting costs like everyone else.
I would prefer to Keep the Panasonic logo(makes the wife happy) and use the correct remote I already have.

Looks like I have a few options:
1. wait for the exact Panasonic board for the 55" to show up on ebay
2. Use the same board model # and version, from ebay but it's for the smaller Panasonic 50" tv. Same TV series though. HOPE that when I reload the 55" firmware for this TV, all is good.
3. Use same board model #, version but for a DIFFERENT brand TV. Those boards are readily available from westinghouse, seiki, element, and even kenmore. In theory these should work too, but I'm not sure it will take the Panasonic firmware. Depends if the SW does some kinda of check or is it just looking for any *.bin file. It might be even looking for a naming convention of the file differently then what Panasonic would do. These boards are cheaper but it seems a little too risky of an approach.

I'm getting anxious since this TV is dissected on our living room table...so gotta try something soon. It's great that some ebay sellers have returns but yes, typically the restock free + return shipping.

[dskall]

Re: Panasonic TC-55CX400U - stuck on logo

Changing firmware from one brand to another is not as easy as updating from usb. It would take removing the eeprom and reprogramming

[g20zoom]

Re: Panasonic TC-55CX400U - stuck on logo

Thanks for that info. Very good to know I can't just swap brands with a new bin eeprom file and a usb reboot.

What do you think about using a Panasonic board for a different size tv, same model series, same main board, but reflashing using the bin file for my exact size/model ?


Anybody know about replacing the NAND flash/eeprom?
Do you have to remove, copy contents to new chip, then resolder new one in?
And if the nand has failed to write presumably, can you still copy it?
I'm sure more trouble then a new board but I can probably find a person to solder smt at work. But the copy part I'm not sure about.

[g20zoom]

Re: Panasonic TC-55CX400U - stuck on logo

TV fixed!

Since Seiki is the OEM manuf. for this Panasonic TV, I went with the 55" Seiki mainboard with the same board/version number after consulting with my firmware friend(doesn't do TVs but just to get an idea how these things work). Turns out the Seiki board had one less USB port, which I missed in the pics, but it still had the usb 2.0 port, so all was good.

It powered up with the Seiki logo, and all seemed to work fine. I didn't have a remote...nor a universal one, so I said what the heck..and I used the Panasonic firmware for my TV. The firmware upgraded, it rebooted in a color check of green/white/red/blue/etc...and kept cycling! slight panic mode, but I powered off and removed the USB with firmware. Rebooted, Seiki came up, but when I went to the menus, it's now Panasonic. Plus my Pansonic remote worked too.

Anyways TV is working great now!

[dskall]

Re: Panasonic TC-55CX400U - stuck on logo

Good to know. Didn't think you could change brands from usb