Reply With Quoteloopyloo (19-08-17)
AFAIK the CPU is separate to the propriety 'Engine' chip which handles all TV functions including menus, tuner control etc. Not sure where the audio is sourced from but it's likely to be that chip as well and you could get lucky to find a peripheral component is the cause, just going to be a nightmare to trace it all out to narrow down the site of the fault.
Audio appears to be sourced from IC105 (LGE2112) which also controls the tuner etc etc so that's a common point for audio & video
Last edited by Skepticist; 19-08-17 at 02:09 AM.
loopyloo (19-08-17)
Had another poke around and IC105 is the heart of everything looking like it's a custom chip containing analog and digital processing - it is the CPU.
It controls peripheral devices like the tuner, MICOM chips etc via I2C interfaces, provides USB interfaces and virtually does everything
If the tuner was damaged there'd be no AV but the menu, startup logo etc should be working so it all seems to come back to that IC105 as the problem.
There's a history of those BGA 'engine' chips failing and requiring 'reballing' to get them going again which is very hit & miss.
Last edited by Skepticist; 19-08-17 at 12:16 PM.
loopyloo (19-08-17)
That's good information.Originally Posted by Skepticist
I've been looking but can't seem to find a main board block diagram that might explain how the main board systems work with each other.
From what I could make out it appeared that the MICOM is the cpu. When I was looking at the power supply I wondered about the MICOM there. I thought oh maybe it stands for something something communication or something like that, but from what I've read so far it stands for micro computer (hmmmm too logical). Apparently they are meant to control just a section of a circuit or I guess the whole circuit if it's small. Some posts from other forums (where they're talking about Samsung TVs) say the MICOM basically controls the whole main board by telling the other chips how to talk to each other so if that's the case then the MICOM is the cpu and the LGE2112 is the dedicated video controller. They say the MICOM has it's own firmware which is accessed by the service menu and any attempt to change it bricks a TV and no one knows how to restore it. Not sure if my understanding of it is right yet. I think a good block diagram might help.
So either the Micom tells the video chip what to do or the video chip tells the MICOM what to do, I guess that means both are in question.
I've had reasonably good success restoring video chips with my heatgun or oven but I think I'll keep that as a last resort. It might be better to trace out the power lines to the video chip and the MICOM first.
One thing I don't get is what are the updates loaded into ? another eeprom ?
Almost everything works on the TV works. Front buttons, remote, it accepted an update (I think), it powers on/off, backlights work and dim, it certainly points to the video chip. Meaning it's either electrically gone, (and if that's the cpu then it's only partially gone) or just loss of connection with the board. That would be very coincidental with the lightning strike or maybe from shock. hmmmm.
I'm thinking the panel would be ok because if the panel received damage I would think there'd be more damage to the main board also, since it has to pass through there.
It's tricky to trace the video chip because it doesn't have pin numbers as such, but a grid instead, plus the connections are not available so I have to go looking for their nearest component to pick up on.
PS I just saw a transistor that's about the size of a sugar crystal . No kidding ... criikey !
Last edited by loopyloo; 19-08-17 at 01:33 PM.
It has EEPROM which I think is for saving current settings like channels, volume etc when the set is powered down.
The actual firmware for the engine chip is stored in a 4Gb flash chip and the MICOM chips appear to be 'satellite' microcontrollers that collect diagnostic data and perform a few other functions as well but all at the control of the big chip.
There should be a way to 'reflash' the firmware but that might require propriety equipment and interface to do so.
loopyloo (19-08-17)
Just tried a computer monitor from the VGA socket and find it receives nothing so I can prob rule out bad panel and T-con.
Trace back the signals on the VGA socket and they come from LGE2112 so all the digital to analog magic happens inside that chip, including audio extraction.
loopyloo (19-08-17)
Closer inspection: it appears that that video/audio separation occurs in the tuner module so there's a chance that the tuner could be faulty but that doesn't explain the lack of a logo or menus.
loopyloo (19-08-17)
But what about A/V or HDMI inputs ? Are you saying they go through the tuner too ? surely not
Just realized a mistake, testing with a monitor won't work. The VGA is an input not output ha ha
Last edited by loopyloo; 19-08-17 at 06:53 PM.
Do the HDMI inputs/outputs work ?
Sent from my LON-L29 using Tapatalk
loopyloo (20-08-17)
No can't get HDMI to work either.
Normally when you plug something into an LG TV (going by my other LGs) a pop up will ask if you want to use it and it defaults to yes, so I just pressed ok on the remote but the screen stayed the same.
Last edited by loopyloo; 19-08-17 at 10:45 PM.
Loopy, I see that you located a schematic (circuit) diagram for the beast but you might need other info. also, so try .
He has a vast store of service manuals, circuit diagrams, training manuals etc., which are freely available, although there is provision for making a donation towards website costs via Paypal.
The website is also very good for technical information and help.
Bookmark them for future reference as you seem to have a penchant for fixing things.
loopyloo (20-08-17)
Yep, saved.
Thanks for that , and you're right. One of my most favorite things to do is take something that's broken and fix it or modify an item and make it better or just make it myself. Few other things give me such pleasure.
Sometimes I think my thirst for knowledge is increasing, sometimes almost like an obsession, I wonder, is that a bad thing ? Anyway, as age is increasing I have little else to do.
Last edited by loopyloo; 20-08-17 at 01:47 AM.
There's nothing wrong with a good, healthy thirst for knowledge. And it's good that you have something you enjoy doing with which to occupy your time, particularly with advancing age and the limitations it can place on one's physical ability.
The added advantage is that it keeps your brain active and helps to prevent too much introspection and "moping around", which can be very destructive if taken to extremes.
I've seen many people deteriorate rapidly upon retirement simply because they had lacked the foresight to develop hobbies and other enjoyable pastimes, which would sustain them into old age, when they were younger.
loopyloo (20-08-17)
Having a bit of trouble with the circuit terminology/pin markings.
Page 29 MICOM : I don't understand pins 8,9,34 and 33 : "power on/off2_2", "power on/off 2_3", "power on/off 2_4", "power on/off 2_1"
I'm currently working off page 28. Power
Last edited by loopyloo; 20-08-17 at 04:09 PM.
Looks like power on and power off is done in a sequence controlled by the MICOM chip IC3000
EG +1.2V_MTK_CORE then +1.5V_DDR etc and shutdown is staged in reverse order
That chip also mutes the audio amp (possibly during channel changing for example)
loopyloo (20-08-17)
So like the MICOM is the hardware controller and IC105 is the software controller ?
What's the MTK core ? , IC2400 ? , I read somewhere it stands for mediatek.
Last edited by loopyloo; 20-08-17 at 10:05 PM.
Probably does stand for mediatek - seems to be multiple complex devices, analog and digital, inside IC105 each with its own different voltage power supply.
MTK_CORE & MTKAVDD is 1.2V, VDD3V3 (3.3V), DAC3V3 for example.
The chip also has provision for a smartcard interface (not used in the Aus variant)
Last edited by Skepticist; 20-08-17 at 10:32 PM.
loopyloo (20-08-17)
If all else fails - I see a reasonable success rate achieved by placing the main board in the oven at 200C for 10 minutes which can fix bad solder connections on the BGA 'engine' chip (and others).
I only see that method succeeding in cases where the set 'freezes' at the initial logo display and sometimes solves HDMI not connecting problems but worth a try as a last resort perhaps if nothing definite can be found.
There are a number of youtube vids demonstrating the method.
Yes I've used the oven treatment with success.
I did wonder if the most sensitive thing on the board could be the problem and fixed this way....the ram. That might also explain no sound since it appears like the TV won't boot.
Last edited by loopyloo; 21-08-17 at 12:56 AM.
But the CPU was showing signs of life when a USB drive was plugged in?
Having all the functions in a single package makes it almost impossible to faultfind in there. It does have a JTAG interface but probably needs 'secret' software to make use of it.
You could probe the I2C tracks to the external devices like the tuner with a CRO for activity to get an idea of what's going on but it's a jungle in there.
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