LG 55uf7787 stuck on logo

[Dannyx]

Good day folks. Busy day today Got another telly in and this one is going to be a tough nut to crack: very big, very new, no info on it....mission impossible.

LG junker's stuck on logo...1000 euros worth of TV only to have it do THIS after 2 years...that's enough to make you want to attack it with a baseball bat. Makes ME angry, I can imagine what the chaps felt like...

Haven't taken it apart yet just because I haven't got the space, but I imagine that would be useless outside being able to provide some of you helpful chaps with some model numbers and stuff, since I imagine nobody can spare a service manual or a dump for this thing.....they haven't "leaked" yet, with it being so new. I HOPE I can read and backup the EEPROM just in case...
just so I can say I at least did SOMETHING to it

The guy said he turned it off whilst it was attempting a software update or something, so that might be one of the causes...or the board simply crapped out...

[ducky29]

Re: LG 55uf7787 stuck on logo

Mainboard has gone bad. Try resetting the eeproms, or if you have the right tools use a dump for the flash memory. If any of these do not work you have to replace the mainboard.

[Dannyx]

Re: LG 55uf7787 stuck on logo

I figured...POS Haven't opened it up yet to see what's in there, since it's this big behemoth and I've got the table occupied ATM...

[CapLeaker]

Re: LG 55uf7787 stuck on logo

Freeze the EEPROM with a can of air upside down, then turn the TV on.

[Dannyx]

Re: LG 55uf7787 stuck on logo

I'm inside this telly now and I'll be honest: I cannot find an EEPROM chip...either I'm not seeing it or it loads everything off the flash...

EDIT: I'm about to try something rather daring: flash it via RS232...the first step is to actually see if it even connects with it being stuck on the logo and all. I'll try making myself an adapter cable, based on THIS, which is a different model, but hopefully the pinout hasn't changed. TX to RX and RX to TX, into the CH341 programmer set as COMx, putty and attempt a connection. If done right, based on another source, I should see Mstar show up in the console window....if I'm lucky to even make it that far, I grabbed a firmware file from LG for this model and I SHOULD send that over to it by typing SWUZ....what could possibly go wrong ?

[Dannyx]

Re: LG 55uf7787 stuck on logo

Unfortunately no, my idea didn't work: there's no response whatsoever. Either the pinout of the jack is not correct (though I tried flipping TX and RX around), the interface is not RS232 or the TV simply doesn't respond because it's dead.

There's another header on the board clearly labeled RS232, but good luck finding the pinout for it. I also see a MAX IC on there which to my recollection is a level shifter, so it could be that it's expecting a "purely" serial interface, like on a motherboard, on that jack. Since I'm using it with a USB adapter (the CH341), it could be that it's not at the right level and I'd need to use that header with the CH341...I dunno

[tom66]

Re: LG 55uf7787 stuck on logo

You'll probably find that small white connector has a serial port on it. You can use a scope to see if there's any activity when you power it on.

[Dannyx]

Re: LG 55uf7787 stuck on logo

Don't have a scope sadly...I managed to find the GND pin though, so I COULD wing it by trying different combinations, but there's 4 pins. 1 more than your regular RS232, so I'm not sure what the extra one does: TX, RX, GND, ?...something could blow if I just randomly connect them. I'll try the jack once again, this time with an older PC with an actual serial port, just to rule it out...getting win 7 installed on the thing right now

[tom66]

Re: LG 55uf7787 stuck on logo

Yeah, you'd need a scope to do this. Sorry.

[Dannyx]

Re: LG 55uf7787 stuck on logo

I made another discovery: Putty refuses to run on Win XP and I couldn't get win 7 on the junker with the COM port, but my theory was correct: using that hyperterminal thing win XP has, I DO get some response from the TV, which is:

MIU0-DQS-OK
MIU1-DQS-OK
XLC_

So there may be something there...

[tom66]

Re: LG 55uf7787 stuck on logo

That's the RAM training. DQS is the DataN write strobe, so byte writes can be masked.
Looks like it passes that at boot, but everything subsequent fails.

[Dannyx]

Re: LG 55uf7787 stuck on logo

Dead CPU or something ? Either way it's trash - I'm just curios to learn more in-depth

[tom66]

Re: LG 55uf7787 stuck on logo

Dead CPU or something ? Either way it's trash - I'm just curios to learn more in-depth

Could be a BGA failure but I expect after RAM training it will try and load the Linux kernel.
That isn't happening for one reason or another, bad bootloader would be my guess, unless the kernel's first executable page is trash, but usually u-boot or whatever these run will decompress the kernel first.
Odd, in any case.

[Diah]

Re: LG 55uf7787 stuck on logo

need to send command via IR "IN_STOP" this will reset the eeprom to factory condition

[Dannyx]

Re: LG 55uf7787 stuck on logo

How would one go about doing that ?

[ducky29]

Re: LG 55uf7787 stuck on logo

need to send command via IR "IN_STOP" this will reset the eeprom to factory condition

You need to have the service remote in order to do that.

[tom66]

Re: LG 55uf7787 stuck on logo

How would one go about doing that ?

LG factory remote. Available on eBay.

[Dannyx]

Re: LG 55uf7787 stuck on logo

I reckoned....I have obsessed with this several times now, but too bad there isn't a way to emulate all these remotes. The prices are way up there apparently.

EDIT: actually I think there's apps that do this with the IR blaster of a phone....I have a HTC lying around that would do nicely. I can accept having 10 apps than 10 remotes I remember I have done this before with a Samsung which had a locked service menu and wouldn't let me change some panel options. It was as easy as downloading the app, pointing the thing at the TV and I was in.

[vinceroger69]

Re: LG 55uf7787 stuck on logo

this thread maybe worth a read the software post 19
https://www.badcaps.net/forum/showth...service+remote

[Dannyx]

Re: LG 55uf7787 stuck on logo

Following the information HERE, which is very handy, is there an app which functions like a programmable remote and allows you to enter those codes in it like with a Logitech Harmony ? I'm inclined to get myself a Harmony, despite having this discussion before and someone suggesting they're rather sucky and not worth it...I'd get it just for the service codes. I've got them for LG now, I wonder if there are any for Samsung too...