Sharp LC-70LE600U Won't Turn On

[befuddled]

Hi,

I have a Sharp Aquos LC-70LE600U LCD tv. It was purchased in 2013 (I think).

* For about the last year or two, it has the faded triangle in the lower left corner.
* For about the last six months or so, it randomly makes clicking sounds but everything continued to work.

A couple nights ago, it shut off on its own... several times in a row. After five or six times it just simply would not turn back on. The tv has already been replaced, but I want to see if I can get it working again.

* Absolutely nothing happens when you press power.
* When you plug it in, the chevron light comes on for one second then goes out.
* Nothing on any of the boards makes any kinds of noises whatsoever when plugging it in or pressing the power button.

I pulled the cover off and this is what I've found:

* On the PD plug on the power supply board, pin PD-15 BU5V has the required 5 volts.
* No other pin has voltage.
* Pressing the power button does not pass the 5 volts to the pin PD-14 PS_ON.

Over on the main board, if I jump those two pins (easier to do on the main board), I get appropriate voltages on the other pins EXCEPT FOR:

* PD-1-2 PNL 12V ---- has 0 volts
* PD-16 PNL_POW ---- has 0 volts



I simply do not know where to go from here!

As soon as I post this, I will go take pictures of the configuration of the boards in the tv as well as of each individual board and post them.

[befuddled]

Re: Sharp LC-70LE600U Won't Turn On

So here's the pictures...

better pics and more info can be provided if needed and any help would be GREATLY appreciated!!

(hopefully I've done this right )

[befuddled]

Re: Sharp LC-70LE600U Won't Turn On

So I'd tried numerous combinations of buttons on the side held while plugging in to force the tv on to no avail. Well, I just saw a new combination I'd not seen before on another thread. Lo and behold, it turned on. If I turn it off, it won't turn back on again with the power button.

So I guess I'm sorta back at square one with a different angle of searching.

If anyone could steer in ANY direction, preferably the correct one it would be greatly appreciated!

[budwich]

Re: Sharp LC-70LE600U Won't Turn On

lots of 70 threads to read... do the regular "disconnect tcon to panel cable" one at a time and see what happens. If nothing, get out your meter and do some measurement of the connector at the power board which usually has labels for the pins there.

[befuddled]

Re: Sharp LC-70LE600U Won't Turn On

lots of 70 threads to read... do the regular "disconnect tcon to panel cable" one at a time and see what happens. If nothing, get out your meter and do some measurement of the connector at the power board which usually has labels for the pins there.

Sorry, I've already done the unplugging-of-connectors test... each one individually with not one of them making a difference.

I've read so many threads that address similar symptoms but none that really solve my issue.

In my first post I included that all of the pins are as expected except for four, PD-14 PS_ON, PD-1-2 PNL 12V, and PD-16 PNL_POW which all have 0 volts.

But I don't know what that is telling me!

[R_J]

Re: Sharp LC-70LE600U Won't Turn On

You have standby 5v from the power supply to the main board, make sure the 5v does'nt drop when you press the power button. If the 5 volts standby stays up the main board should supply the PS_ON voltage, when the power button is pressed. If it does'nt, the fault is very likely on the main board. Without the PS_ON, the power supply will remain in the standby condition.
Shopjimmy does offer a eeprom, so that might be the problem, or you can try unplugging the tv, freezing the eeprom with cold spray, pluging in the tv and see if it turns on, sometimes this trick works but not always.

[budwich]

Re: Sharp LC-70LE600U Won't Turn On

Sorry, I've already done the unplugging-of-connectors test... each one individually with not one of them making a difference.

I've read so many threads that address similar symptoms but none that really solve my issue.

In my first post I included that all of the pins are as expected except for four, PD-14 PS_ON, PD-1-2 PNL 12V, and PD-16 PNL_POW which all have 0 volts.

But I don't know what that is telling me!

yes but there are a lot more pin labeled that you have indicated what they read.

[befuddled]

Re: Sharp LC-70LE600U Won't Turn On

You have standby 5v from the power supply to the main board, make sure the 5v does'nt drop when you press the power button. If the 5 volts standby stays up the main board should supply the PS_ON voltage, when the power button is pressed. If it does'nt, the fault is very likely on the main board. Without the PS_ON, the power supply will remain in the standby condition.
Shopjimmy does offer a eeprom, so that might be the problem, or you can try unplugging the tv, freezing the eeprom with cold spray, pluging in the tv and see if it turns on, sometimes this trick works but not always.

Ah... so you mean while I'm literally pressing the power button? Sorta like a battery load test in a car, test voltage while turning the engine over with the starter. I'll check that this afternoon.

As for the eeprom, is that on the main board or the tcon? There's nothing that looks like a large computer chip on the main board.




Also, the large chip on the tcon board gets really hot. Like, can't hold your finger on it for more than a second hot. Is that normal?

[befuddled]

Re: Sharp LC-70LE600U Won't Turn On

yes but there are a lot more pin labeled that you have indicated what they read.

So I'm guessing you're more interested in what their labels are? Because I'm pretty sure that by saying the rest of the pins have "appropriate voltages" I'm saying that if pin PD-X is labeled "LBL 13V" then I have 13 volts.

Listen, I'm not trying to be snarky. But please don't tell me "If nothing, get out your meter and do some measurement of the connector at the power board", which you said in your first post when I said I'd already done that followed by a vague (quoted) statement telling me I haven't done something, again, something that I've already done in my first post.

[befuddled]

Re: Sharp LC-70LE600U Won't Turn On

yes but there are a lot more pin labeled that you have indicated what they read.

My point is, if you want a complete list of the pins, labels, and voltage readings, then say so. Don't be vague and condescending.

[nomoresonys]

Re: Sharp LC-70LE600U Won't Turn On

Yes, I would like to see a whole list, it is usually the best place to start troubleshooting, the procedure is #3 below in my signature.

[diif]

Re: Sharp LC-70LE600U Won't Turn On

PD and PNL_POW are panel display and panel power.
Perhaps the issue is on the driver board. The thin board the two cables from the TCON connect to.

[R_J]

Re: Sharp LC-70LE600U Won't Turn On

Ah... so you mean while I'm literally pressing the power button? Sorta like a battery load test in a car, test voltage while turning the engine over with the starter. I'll check that this afternoon.

the only reason I asked for this test is that I have seen some sharp power supplies where the +5v standby would drop as soon as the power button was pressed. If this voltage stays up it is not causing the issue in this case.

The eeprom (or SPI) ic is a 8pin smd, IC8401 located on the main board.

Also, the large chip on the tcon board gets really hot. Like, can't hold your finger on it for more than a second hot

The t-con board must be getting PNL12v as it is supplied directly from the power supply board.
Try disconnecting LVDS cable and PL plug on the T-con board and see if at least the tv's backlights come on.
If all the cables are connected, and the tv IS in standby, there should not be any PNL12V going to the t-con, This voltage is controlled by the PNL_POW line

You earlier said you did not have PNL12V

* PD-1-2 PNL 12V ---- has 0 volts
* PD-16 PNL_POW ---- has 0 volts

So I don't know why the t-con ic would get hot without voltage for the board.

[befuddled]

Re: Sharp LC-70LE600U Won't Turn On

The t-con board must be getting PNL12v as it is supplied directly from the power supply board.
Try disconnecting LVDS cable and PL plug on the T-con board and see if at least the tv's backlights come on.
If all the cables are connected, and the tv IS in standby, there should not be any PNL12V going to the t-con, This voltage is controlled by the PNL_POW line

You earlier said you did not have PNL12V So I don't know why the t-con ic would get hot without voltage for the board.

Sorry, I should've been more clear on this. The chip on the tcon board gets hot when I start the tv using the input and volume down buttons while plugging in the ac cord. Otherwise, just using the power button which does not turn the tv on, no, it doesn't get hot

[R_J]

Re: Sharp LC-70LE600U Won't Turn On

If it reads the buttons "input & Volume down" I suspect the eeprom is ok as the micro knows what to do. Try disconnecting that PL plug on the t-con and see if the tv will turn on. I suspect the main board is seeing a fault and not allowing the tv to turn on, which is normal, so the power supply and main are likely ok. The fact the ic on the t-con is getting hot would suggest either the ic is bad or the panel is bad, Try disconnecting the flat cables between the panel and the t-con and force the tv on (input+vol dn) and see if the ic still gets hot, If it does it is likely the t-con is bad, if it stays cool, the panel is likely bad

[befuddled]

Re: Sharp LC-70LE600U Won't Turn On

So today, twice, the tv has come on upon being plugged in (no buttons pressed) while several other times only flashing the chevron once. Not once has it shown any signs of life upon pressing the power button.

When pressing the power button, 0.0 volts at the pin PD-14 PS_ON. No jump/fluctuation. Nothing.

Here are the pins in numerical order, name/description, tv off plugged in, tv on.

PD-1 PNL12V, 0, 11.91
PD-2 PNL12V, 0, 11.91
PD-3-4 GND
PD-5 UR13.2V, 0, 13.17
PD-6 UR13.2V, 0, 13.17
PD-7-8 UR13.2V (NO WIRES)
PD-9-10-11-12 GND
PD-13 AC_DET, 0.05, 3.26
PD-14 PS_ON, 0.04, 2.81
PD-15 BU5V, 5, 5
PD-16 PNL_POW, 0, 3.21
PD-17 PWM1, 0, 0.47
PD-18 NC
PD-19 DIMMER, 0, 1.68
PD-20 NC
PD-21 OFL (NO WIRE)
PD-22 ERROR, 0, -0.01
PD-23 PWM2 (NO WIRE)
PD-24 STB, 0, 3.2

Just to be clear, all readings while holding the power button are identical to tv off.

Unplugging the flat cables at bottom of tcon and force starting the tv, the large chip does still get quite hot. I just don't know how hot is acceptable.

[nomoresonys]

Re: Sharp LC-70LE600U Won't Turn On

When the tv starts, can you see anything on the screen like text or anything? While shining a flashlight on screen at an angle if needed. Maybe hit the menu see if there's text or anything showing up.

[R_J]

Re: Sharp LC-70LE600U Won't Turn On

Unplugging the flat cables at bottom of tcon and force starting the tv, the large chip does still get quite hot. I just don't know how hot is acceptable

Try disconnecting that PL plug on the t-con and see if the tv will turn on normally. This is how the t-con gets its power not from the flat cables at the bottom

Looking at your voltages in post #16, the main board is working and the power supply is working.
I dont understand what you are talking about here:

When pressing the power button, 0.0 volts at the pin PD-14 PS_ON. No jump/fluctuation. Nothing.

and right below it you have this:

PD-14 PS_ON, 0.04, 2.81

so which is correct? when you push the power button you get 0 volts on PS_ON OR 2.81 volts ?

[befuddled]

Re: Sharp LC-70LE600U Won't Turn On

Disconnecting the PL plug on the tcon also does not allow the tv to turn on.

Starting with the tv off, if I press and hold the power button and take a reading at pin PD-14 PS_ON, there is not change. It still reads 0 volts. You asked me to do this test.

The voltages in my post #16 are with the tv off (standby) followed by with the tv on after force starting it with input and volume down buttons. All readings while pressing and holding the power button and AFTER releasing the power button are identical to the tv being OFF.

The bottom line is that trying to turn the tv on with the power button LITERALLY DOES NOTHING. I know the button works though because it turns it off after forcing the tv on using input and volume down.

[befuddled]

Re: Sharp LC-70LE600U Won't Turn On

When the tv starts, can you see anything on the screen like text or anything? While shining a flashlight on screen at an angle if needed. Maybe hit the menu see if there's text or anything showing up.

When the tv is forced to start, and the couple times it started on its own after being plugged in, it acts as though there is nothing wrong, it shows static, menu, etc.