Sharp Aquos lc-40le600e stuck in standby - no lights flashing

[Tim5000]

Hi everyone,
I've got a Sharp Aquos that is my friends and I said I'd have a quick look at it for him.
He's owned it from new for about 8-9 years.
It recently developed a fault where it will not turn on anymore - the red standby light comes on but that's it...no flashing codes here unfortunately.

There is also no sign of the backlight flashing, or anything on the panel when viewed with a torch.

I've done some very basic checks on the power board and main board.

• Power board is marked RUNTKA609WJQZ.
• Main board is DUNTKF111

If I power the unit on and probe the power board I can see that:

1. CN7501 - BUS5V goes to 5V
2. CN7501 - PS_ON goes to 2.57V
3. CN7501 - AC DET goes to 3.3V
4. CN7501 - PNL_POW stays 0V
5. CN7501 - UR_13V goes briefly high then immediately decays to 0V
6. CN7505 - PNL_12V stays 0V

I've checked the big electrolytic C7144 and there is 400V DC across it.

If I leave all plugs in but remove the backlight, the voltage at UR_13V still collapses.
If I unplug all the boards and backlight, and jumper PS_ON to BUS5V I get UR_13V to go to 13V. PNL_12V stays at 0V.

Any help gratefully received!

[budm]

Re: Sharp Aquos lc-40le600e stuck in standby - no lights flashing

"If I unplug all the boards and backlight, and jumper PS_ON to BUS5V I get UR_13V to go to 13V. PNL_12V stays at 0V."
You will need to also jump PNL_POW with resistor (470 ~ 1000 Ohms) to BUS5V to force on the PNL12V (no cable from PNL12V to T-CON).

[Tim5000]

Re: Sharp Aquos lc-40le600e stuck in standby - no lights flashing

Hi budm, and thanks!
From your info I've jumpered PNL_POW via a 470ohm from BUS_5V and the PNL_12V successfully comes up now.

Again, this is with all other boards disconnected.

I've managed to find the schematic of the power board but I presume we are looking more toward the main board based on this outcome?

[Tim5000]

Re: Sharp Aquos lc-40le600e stuck in standby - no lights flashing

I've since connected all the boards back up (with the exception of CN7501 between the PSU and main board). This includes the backlight.
Fitted the jumpers for PNL_POW and PS_ON and the supplies all come up and look stable on the PSU board.
However nothing different happens with the TV - no backlight comes up and the status is stuck red (presumably because the main board hasn't commanded it to do anthing)?

[budm]

Re: Sharp Aquos lc-40le600e stuck in standby - no lights flashing

If you remove the force on jumpers and try using the remote control combination to force the TV on to see what happen, I do not remember the key combinations.

[Tim5000]

Re: Sharp Aquos lc-40le600e stuck in standby - no lights flashing

I've plugged everything back in and tried tonight to get the tv to turn on but I can't make it come on.
I've tried the sequence in the service manual

2. Entering and exiting the adjustment process mode
1. Press the “MAIN POWER” key on the set of running TV set to force power off.
(Or, unplug the AC power cord of running TV set to force power off.)
2. While holding down the “
(-)” and “INPUT” keys on the set at once, press the “MAIN POWER” key on the set to turn on the power.
The letter “K” appears on the screen.
3. Next, hold down the “
(-)” and “P (-)” keys on the set at once.
Multiple lines of orange characters appearing on the screen indicate that the set is now in the adjustment process mode.
If you fail to enter the adjustment process mode (the display is the same as normal start up), retry the procedure.

I've also tried what I've found for other Sharp sets (Vol Down and Channel Up).

Both no dice unfortuantely after several attempts at each.

[Tim5000]

Re: Sharp Aquos lc-40le600e stuck in standby - no lights flashing

So a bit of progress.
Despite many more attempts with all leads plugged in I couldn't get into the service menu.
So a little inspiration and I disconnected the two large backlight connectors CN7606 and CN7607 from the power board.

Once they were unplugged the set would go from red light to no light when toggling the set on and off (not flashing, but just on and off instead of on and green). So this tells me the main board was actually a little more alive than previously thought.

From here (again with the backlight connectors removed) I managed to get into the service menu (checked with a torch). I reset the error codes and plugged it all back in.

Resetting the error codes made no difference.
So it's now in a state that:
* With the backlight plugged in the set hardly won't turn on (no error codes flashing).
* With the backlight unplugged the set won't turn on but the power led goes red and off.
* With the backlight unplugged and FORCING on with (Input/Vol down) the set powers up and appears to operate. D3322 is flashing on the main board.

[Tim5000]

Re: Sharp Aquos lc-40le600e stuck in standby - no lights flashing

A little bit more progress/update.
If I plug in the black backlight connector (CN7607) but leave the white backlight connector off (CN7606), the tv still behaves as per my previous post.

However in this state the backlight comes up. I can see that all the elements look OK.
I can also see that after my playing about there are some elements in the error codes.
These MAY be because I've been running with cables unplugged? Or they may be why the tv hasn't powered up:

STANDBY CAUSE: 1B 1B 1B 00 00
1) 17683H 00M
2) 17683H 00M
3) 17683H 00M
4) 00H 00M
5) 00H 00M

[Tim5000]

Re: Sharp Aquos lc-40le600e stuck in standby - no lights flashing

I've managed to get a little time to investigate this further.
If I remove some pins from CN7606 I can get the unit to go into the service menu with the backlight on.
The pins relate to backlight rows 2 and 3.

With those pins connected the tv will not turn on or enter the service menu.

If i swap the pins such that the backlight pins go to different driver pins on the psu board the fault seems to follow the backlight. So it sounds like the 2 backlight rows are faulty.

However if I remove the pins for backlight 2 & 3 and enter the service menu, I can plug the pins back in while the set is on (carefully of course) and they all light up. So there are no dead LEDs on the set.

Any thoughts please? It sounds like the tv is maybe just too tight with it's tolerances in the fault detection circuit on an old tv?

[nomoresonys]

Re: Sharp Aquos lc-40le600e stuck in standby - no lights flashing

Can/did you do a factory reset from the service menu?

[Tim5000]

Re: Sharp Aquos lc-40le600e stuck in standby - no lights flashing

I had done that earlier but it didn't help.

But in fact I've just fixed it!
So...interestingly (but maybe not surprisingly for some of the experts) the problem was down to a dead gnat/midge in the LED2 connector - at the backlight end, not the PSU end.

Once I'd removed that I could power up in the service menu and again reset the status.

After that the TV now powers on properly.
And fortunately for my friend no new boards required.

Thanks for the input.

[nomoresonys]

Re: Sharp Aquos lc-40le600e stuck in standby - no lights flashing

Well done

[zwarder]

Re: Sharp Aquos lc-40le600e stuck in standby - no lights flashing

Very similar symptoms here but unfortunately dead & flickering leds were the cause