Hi all

I have an LG C9 OLED TV which turns off a few seconds after it is
switched on either by the remote or the power button. The sequence is

standby light is on

press the button and it goes off

A green line starts to be drawn on the screen

Goes back into standby and standby light goes on.

I have checked the power coming out of the power board and seems to be
correct (including different voltages when in standby Vs on where
appropriate). I have also checked the voltages on the t-con board and
again they seem to be correct.

So thinking are are now down to either the master board or the panel
itself, I tried the following

Baked the master board in the oven in case there was a dodgy connection
(200 Deg C for 10 mins). No change

Removed all the panel connectors from the t-con board (thinking of the
panel was shorting it would at least stay powered on) but again no
change.

Added each of the 4 panel connectors back one at a time (only one
connected at a time) again no change.

So... Now at a loss as to where to go next. Seems a shame to bin the TV
if it can be replaced. Anyone have any ideas please?

Many thanks

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

On 26/04/2025 10:42, leenowell wrote:

Hi all

I have an LG C9 OLED TV which turns off a few seconds after it is
switched on either by the remote or the power button. The sequence is

standby light is on

press the button and it goes off

A green line starts to be drawn on the screen

Goes back into standby and standby light goes on.

I have checked the power coming out of the power board and seems to be correct (including different voltages when in standby Vs on where appropriate). I have also checked the voltages on the t-con board and
again they seem to be correct.

So thinking are are now down to either the master board or the panel
itself, I tried the following

Baked the master board in the oven in case there was a dodgy connection
(200 Deg C for 10 mins). No change

Removed all the panel connectors from the t-con board (thinking of the
panel was shorting it would at least stay powered on) but again no
change.

Added each of the 4 panel connectors back one at a time (only one
connected at a time) again no change.

So... Now at a loss as to where to go next. Seems a shame to bin the TV
if it can be replaced. Anyone have any ideas please?

Many thanks

Fixing modern SMD electronics requires a hot air reflow machine, a
microscope, an infra red camera lots of flux, low temperature solder, an accurate soldering iron and very steady hands.

Sometimes its possible to spot the bulgy capacitor spewing its guts out.
But no one supplies circuit diagrams at all. And many chips are custom
made for the manufacturer and are not available as spares. If you can cannibalise another non working set, that's good.

If you want to invest ion a couple of thousand quids worth of board
repair kit or pay someone £60 an hour to try and fix something that's
not worth £50...and have no guarantee it will subsequently work, be my
guest.

The long and the short of it is that modern consumer electronics - and
even industrial electronics - has limited repairability. Its just about
worth fixing a £1000 smart phone or laptop, but not a TV that you can
probably get in Currys for £80...


--
Outside of a dog, a book is a man's best friend. Inside of a dog it's
too dark to read.

Groucho Marx

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

On Sat, 26 Apr 2025 11:11:46 +0100
The Natural Philosopher <[email protected]d> wrote:

On 26/04/2025 10:42, leenowell wrote:

Hi all

I have an LG C9 OLED TV which turns off a few seconds after it is
switched on either by the remote or the power button. The sequence
is

standby light is on

press the button and it goes off

A green line starts to be drawn on the screen

Goes back into standby and standby light goes on.

I have checked the power coming out of the power board and seems to
be correct (including different voltages when in standby Vs on where appropriate). I have also checked the voltages on the t-con board
and again they seem to be correct.

So thinking are are now down to either the master board or the panel itself, I tried the following

Baked the master board in the oven in case there was a dodgy
connection (200 Deg C for 10 mins). No change

Removed all the panel connectors from the t-con board (thinking of
the panel was shorting it would at least stay powered on) but again
no change.

Added each of the 4 panel connectors back one at a time (only one
connected at a time) again no change.

So... Now at a loss as to where to go next. Seems a shame to bin
the TV if it can be replaced. Anyone have any ideas please?

Many thanks

Fixing modern SMD electronics requires a hot air reflow machine, a microscope, an infra red camera lots of flux, low temperature solder,
an accurate soldering iron and very steady hands.

Sometimes its possible to spot the bulgy capacitor spewing its guts
out. But no one supplies circuit diagrams at all. And many chips are
custom made for the manufacturer and are not available as spares. If
you can cannibalise another non working set, that's good.

If you want to invest ion a couple of thousand quids worth of board
repair kit or pay someone £60 an hour to try and fix something
that's not worth £50...and have no guarantee it will subsequently
work, be my guest.

The long and the short of it is that modern consumer electronics -
and even industrial electronics - has limited repairability. Its just
about worth fixing a £1000 smart phone or laptop, but not a TV that
you can probably get in Currys for £80...

Unfortunately, that is indeed the way of the modern world. A shame, a
great shame, in my opinion. How much stuff is wasted because of this?

When I was still working, in industry, it was even more true of
industrial than domestic equipment.
--
Davey.

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

On 26/04/2025 14:02, Davey wrote:

On Sat, 26 Apr 2025 11:11:46 +0100
The Natural Philosopher <[email protected]d> wrote:

On 26/04/2025 10:42, leenowell wrote:

Hi all

I have an LG C9 OLED TV which turns off a few seconds after it is
switched on either by the remote or the power button. The sequence
is

standby light is on

press the button and it goes off

A green line starts to be drawn on the screen

Goes back into standby and standby light goes on.

I have checked the power coming out of the power board and seems to
be correct (including different voltages when in standby Vs on where
appropriate). I have also checked the voltages on the t-con board
and again they seem to be correct.

So thinking are are now down to either the master board or the panel
itself, I tried the following

Baked the master board in the oven in case there was a dodgy
connection (200 Deg C for 10 mins). No change

Removed all the panel connectors from the t-con board (thinking of
the panel was shorting it would at least stay powered on) but again
no change.

Added each of the 4 panel connectors back one at a time (only one
connected at a time) again no change.

So... Now at a loss as to where to go next. Seems a shame to bin
the TV if it can be replaced. Anyone have any ideas please?

Many thanks

Fixing modern SMD electronics requires a hot air reflow machine, a
microscope, an infra red camera lots of flux, low temperature solder,
an accurate soldering iron and very steady hands.

Sometimes its possible to spot the bulgy capacitor spewing its guts
out. But no one supplies circuit diagrams at all. And many chips are
custom made for the manufacturer and are not available as spares. If
you can cannibalise another non working set, that's good.

If you want to invest ion a couple of thousand quids worth of board
repair kit or pay someone £60 an hour to try and fix something
that's not worth £50...and have no guarantee it will subsequently
work, be my guest.

The long and the short of it is that modern consumer electronics -
and even industrial electronics - has limited repairability. Its just
about worth fixing a £1000 smart phone or laptop, but not a TV that
you can probably get in Currys for £80...

Unfortunately, that is indeed the way of the modern world. A shame, a
great shame, in my opinion. How much stuff is wasted because of this?

I am sure back in the day people were bemoaning that it took thousands
of pounds of equipment to repair a vacuum tube. And you just had to
throw them away.

And then the problem with these integrated circuits was that you just
couldn't repair them. You had to throw them away.

Well today the printed circuit BOARD is a component...that you just
'throw away'.
Mostly.

When I was still working, in industry, it was even more true of
industrial than domestic equipment.

Was it? I would have thought the opposite.

--
Canada is all right really, though not for the whole weekend.

"Saki"

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

On 26 Apr 2025 at 10:42:17 BST, leenowell wrote:

Hi all

I have an LG C9 OLED TV which turns off a few seconds after it is
switched on either by the remote or the power button.

snip

So... Now at a loss as to where to go next. Seems a shame to bin the TV
if it can be replaced. Anyone have any ideas please?

If it's less than say 5 years, I'd try it on with the retailer. OLED and LG is supposed to be 'premium', and I reckon you could make a half decent case if it isn't too old.

Quite pleased/surprised to find that Richer Sounds gave a 6 year warranty FOC with my LG OLED.


--
Cheers, Rob, Sheffield UK

"My humble friend, we know not how to live this life which is so short yet seek one that never ends."
-- Anatole France

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

On 4/26/25 15:16, RJH wrote:

On 26 Apr 2025 at 10:42:17 BST, leenowell wrote:

Hi all

I have an LG C9 OLED TV which turns off a few seconds after it is
switched on either by the remote or the power button.

snip

So... Now at a loss as to where to go next. Seems a shame to bin the TV
if it can be replaced. Anyone have any ideas please?

If it's less than say 5 years, I'd try it on with the retailer. OLED and LG is
supposed to be 'premium', and I reckon you could make a half decent case if it
isn't too old.

Quite pleased/surprised to find that Richer Sounds gave a 6 year warranty FOC with my LG OLED.

As I remember it, the Consumer Rights Act 2015 (and EU legislation), had
the concept of "reasonably durable". I think for many long life items,
this was six years. So Richer Sounds may just have been recognising a
default consumer right.

I think a modern TV should be expected to last 6 years. Worth contacting LG.

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

On Sat, 26 Apr 2025 14:02:43 +0100
Davey <[email protected]d> wrote:

On Sat, 26 Apr 2025 11:11:46 +0100
The Natural Philosopher <[email protected]d> wrote:

The long and the short of it is that modern consumer electronics -
and even industrial electronics - has limited repairability. Its
just about worth fixing a £1000 smart phone or laptop, but not a TV
that you can probably get in Currys for £80...

Unfortunately, that is indeed the way of the modern world. A shame, a
great shame, in my opinion. How much stuff is wasted because of this?

When I was still working, in industry, it was even more true of
industrial than domestic equipment.

Broadcast TV, avionics and medical is still worth repairing, due to the astronomical cost and the unwillingness of customers, who are
relatively few and have a great deal of spending power, to accept
hugely expensive goods which are unrepairable.

Even so, I have written off three camera control panels, which are
pretty much a single PCB which contains... wait for it,,, a *400* pin
IC. This is obviously a ball grid array, and the slightest flexing of
the PCB will break a few joints, and even the factory will not offer an economic repair.

Even worse is stuff which isn't broken, but has no practical use. On my
dining room table is an HP business computer, has Win10 but can't do
Win11, and in a few months it will be useless to Windows users like my
wife. It's only about half as powerful as my current HP desktop, so it's
of use to me only as a backup. If the only alternative is literally
throwing it away, I might keep it for that.

--
Joe

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

On Sat, 4/26/2025 5:42 AM, leenowell wrote:

Hi all

I have an LG C9 OLED TV which turns off a few seconds after it is
switched on either by the remote or the power button. The sequence is

standby light is on

press the button and it goes off

A green line starts to be drawn on the screen

Goes back into standby and standby light goes on.

I have checked the power coming out of the power board and seems to be correct (including different voltages when in standby Vs on where appropriate). I have also checked the voltages on the t-con board and
again they seem to be correct.

So thinking are are now down to either the master board or the panel
itself, I tried the following

Baked the master board in the oven in case there was a dodgy connection
(200 Deg C for 10 mins). No change

Removed all the panel connectors from the t-con board (thinking of the
panel was shorting it would at least stay powered on) but again no
change.

Added each of the 4 panel connectors back one at a time (only one
connected at a time) again no change.

So... Now at a loss as to where to go next. Seems a shame to bin the TV
if it can be replaced. Anyone have any ideas please?

Many thanks

Block diagram. No indication of a four pin TTL level debug header.

https://www.avsforum.com/attachments/lg-oled-c9-blok-diagram-jpg.2626438/

( https://www.avsforum.com/threads/official-2019-lg-c9-consolidated-info-faq-troubleshooting-firmware-more.3075344/page-6 )

The interface controls appear to be a subassembly in the lower right corner
of that diagram.

A Google shows as many firmware reasons for failure, as hardware ones.

An HDMI cable can short out the +5V. An HDMI cable can also receive
a command via CEC, to shut off.

Paul

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

On 26/04/2025 17:24, Joe wrote:

Even worse is stuff which isn't broken, but has no practical use. On my dining room table is an HP business computer, has Win10 but can't do
Win11, and in a few months it will be useless to Windows users like my
wife. It's only about half as powerful as my current HP desktop, so it's
of use to me only as a backup. If the only alternative is literally
throwing it away, I might keep it for that.

Depending on how old and what processor /motherboard you could try this:

<https://www.pcguide.com/windows-11/how-to/install-windows-11-unsupported-cpu/>

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

Thanks very much for the info Paul. Unfortunately it does this without
anything connected to the TV although maybe something shorted it which
fried something?

Seems a shame that there is no way of troubleshooting the master board
so either you buy one on the off chance it might be that or bin the TV I
guess. Since there is a green line appearing when it starts to turn on I
wonder if this is an indication that it is the panel?

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

On 28/04/2025 08:51, leenowell wrote:

Thanks very much for the info Paul. Unfortunately it does this without anything connected to the TV although maybe something shorted it which
fried something?

Seems a shame that there is no way of troubleshooting the master board
so either you buy one on the off chance it might be that or bin the TV I guess. Since there is a green line appearing when it starts to turn on I wonder if this is an indication that it is the panel?

My guess, the power supply is not giving the full beans current, and
instead is going into fault mode. Full beans may not be available due to
charge failing capacitors on the secondary side of the switch mode
supply, which can be checked with a ESR meter. Or you may have other
capacitors failing short - freezer spray, thermal imaging camera?

There are a few youtube vids around on diagnosing TV faults, but you
probably haven't time to watch them all. However, try your hand at
writing a prompt for an AI to help diagnose it.

"I have an LX xxxx TV to fix, the power led only lights for 5 seconds.
What should I look for in the power supply. Can you show me part references"

When I just tried this, it came back to me with a question

Do you already have the TV opened? (If yes, you can tell me the PSU
model number — it's usually printed like "EAYxxxxxxx" or "BN44-xxxxxx."

Then you get specific stuff like

"Most common failure points on BN44 boards (which are made OEM by
Samsung....)

QP801 or QM801/QM802 (Shorted FETs)

DP801/DP802 (shorted Schottky rectifiers)

Startup resistors near ICU801S

Bad optocoupler PC801S

Capacitors bloated or high ESR

Cold solder joints, especially at transformer pins and diodes

Quick First Tests You Should Do:
Step What to Check Expected Result
1 Test for short between HOT ground and VCC (Drain to Source on big
FETs) Should NOT be a dead short
2 Check standby voltage at CNM803/CNM802 Should have 5V or 3.3V (even with TV off)
3 Check if PFC output voltage rises Should boost from ~170V DC to 380–400V DC
4 Diode mode test output rectifiers No dead shorts both directions 5 Pull mainboard cable and re-test See if PSU stays ON"


And there the rabbit hole descends into a sort of hell where wild geese
are out for you to chase...."

You can ask it to make a trouble shooting flowchart, point out a youtube
video for the PSU, find a schematic etc....

--
Adrian C

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

Adrian Caspersz <[email protected]d> wrote:

My guess, the power supply is not giving the full beans current, and
instead is going into fault mode. Full beans may not be available due to charge failing capacitors on the secondary side of the switch mode
supply, which can be checked with a ESR meter. Or you may have other capacitors failing short - freezer spray, thermal imaging camera?

I was thinking of something like that, also possibly thermals. I have a Philips monitor (BDM4065UC) that'll run for half an hour, then shut off. If you power cycle it it'll run for 5 minutes then shut off, if you repeat it
gets down to 2 seconds. I bought a spare with a cracked screen and swapped
the PSU board, same problem. Next stop is to redo the thermal paste on the heatsinks and try again - but disassembling/reassembling the thing is a
PITA.

For Lee's I'd probably try putting some series resistors in series with the power rails and scoping the current draw. Maybe you can catch a current
spike? Or watch the voltage sag and then shut down as the CPU gets a
power-bad message and bails out.

I wouldn't put a whole lot of store by what's on the screen - normally you
need the timing controller (TCON) to be fully booted before you can expect
to see anything. On an LCD you can see if the backlight comes on, but there isn't a backlight on an OLED panel.

There are a few youtube vids around on diagnosing TV faults, but you
probably haven't time to watch them all. However, try your hand at
writing a prompt for an AI to help diagnose it.

"I have an LX xxxx TV to fix, the power led only lights for 5 seconds.
What should I look for in the power supply. Can you show me part references"

When I just tried this, it came back to me with a question

Do you already have the TV opened? (If yes, you can tell me the PSU
model number — it's usually printed like "EAYxxxxxxx" or "BN44-xxxxxx."

Then you get specific stuff like

"Most common failure points on BN44 boards (which are made OEM by Samsung....)

That seems like plausible-sounding gobbledegook. Yes certain boards have certain faults which are known about in repair forums, but every board is
going to have different component IDs - it's unlikely the optocoupler is
PC8015 on every single one. It's likely to make the problem bigger because
now you're looking for things which don't exist on your board.

If I search for BN44 I find a ton of repair information including people selling repair kits, which didn't need any AI. If a search has not pulled
up information about repairing Lee's board then I'd not expect an AI to contribute anything useful - I expect it just to add a big waste of time.
But I would do some searches over board IDs as it's quite possible that searching by model number may not have matches.

I suppose the AI could be useful if you aren't good at searching...

You can ask it to make a trouble shooting flowchart, point out a youtube video for the PSU, find a schematic etc....

Possibly for generic stuff, but for specific stuff where little detail is available, I expect it'll just make stuff up. And where you had one
problem, now you have two.

Theo

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)