Sharp LC-52LE640U - DET_PNL12V failure

[Baldrick]

Hi all...

I've got myself the above mentioned TV and the 'V' is flashing 2 slow/5 fast which supposedly means 'DET_PNL12V failure'. The TV shows zero signs of life aside from the flashing 'V'.

I've disconnected everything but the 120v from the power supply and used my Fluke to check the pins on the 24-pin connector. I'm only seeing 5v on one pin. That's it.

From what I've gathered, I need to put a load on it by using 1157 bulbs. Is there a good description somewhere describing how to do this? I see no bulging caps or other signs of failure.

If anyone can point me in good direction from here, I'd be grateful.

Thanks.

[niko1969]

Re: Sharp LC-52LE640U - DET_PNL12V failure

Power supply error 2 (*2) D+3.3V error.Most likely you have a problem with hdmi.Check IC1504 and Q1508

[rswest]

Re: Sharp LC-52LE640U - DET_PNL12V failure

Did you ever find a solution to this problem? My LC-70LE650U does the same thing. Thanks.

[R_J]

Re: Sharp LC-52LE640U - DET_PNL12V failure

Try disconnecting the 2 ribbon cables from the panel to the T-con board, then power on the tv, It could have a damaged panel.

[Snwboardr9876]

Re: Sharp LC-52LE640U - DET_PNL12V failure

Sorry to bring back such an old post but I have the same exact situation as baldrick. All my voltages are good for a few seconds when first trying to power on then they all disappear except for standby 5 volts and then my standby light flashes 2 slow/5 fast.

Any luck on a repair or diagnosis?

[freakaftr8]

Re: Sharp LC-52LE640U - DET_PNL12V failure

Start with what R-J mentioned above your post first.
Sharp sets like to throw this error when a shorted or cracked panel is sensed.

[Snwboardr9876]

Re: Sharp LC-52LE640U - DET_PNL12V failure

Tried disconnecting one at a time and powering on but still end up with the same outcome. Also same outcome with both ribbons disconnected. Also should mention no bulging caps.

[budm]

Re: Sharp LC-52LE640U - DET_PNL12V failure

The panel_12V sounds like the T-CON is not getting the 12V to run.
Did you check the SMD fuse on the T-CON to see if it is OK and have 12VDC on both ends of the fuse?
Pictures of the whole back side of the TV that shows all the boards will help.

[Snwboardr9876]

Re: Sharp LC-52LE640U - DET_PNL12V failure

Thanks for the replies guys.


That definitely makes sense, I was trying to find a fuse for the T con board but couldn't locate it and I can't find any diagrams online either.

These are the best pictures of the boards I could find online. When I get home from work ill take better pictures and one of the whole TV so it shows how they're all connected. I can tell you that other than the main Ribbon wire there's another wire that runs from the board with the component jacks and HDMI ports to the T con board. Would that be the power for it? Like I said ill post better pictures when I get home from work but here's a couple for now.



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[budm]

Re: Sharp LC-52LE640U - DET_PNL12V failure

So are you getting 12VDC at connector PD pin 1 and 2.
Report the DCV reading of each pin of the connector PD when TV is off and when power switch is activated.
Pictures are provided by SHOPJIMMY.

[budm]

Re: Sharp LC-52LE640U - DET_PNL12V failure

Also check the command DCV signal for the PANEL_PWR pin 16 to see if it is present.
It looks like Q7120 is the switch transistor that is switched on to supply the 12V panel when PANEL_PWR command signal is present.

[Snwboardr9876]

Re: Sharp LC-52LE640U - DET_PNL12V failure

Here are pictures of the entire TV as promised...

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Okay so I have to admit I'm fairly new to electronics of this sort but I'm an electrician so I'm very teachable.

That being said, I'm unsure of how the pins are laid out. I'm guessing if I'm staring at the board that the odd numbers are closer to me? So it's like 1&2 are parallel to each other and then 3&4 and so on? Does it go from the bottom to top or top to bottom?

That being said how do I test the pins closer to the board on the inside? The outside pins have the metal that I can touch with my lead but I can't get to the inside ones. And when I disconnect the connector I lose power so I can't test that way I guess.

[budm]

Re: Sharp LC-52LE640U - DET_PNL12V failure

The exposed pins that you can see from the top side of the board are the ODD number pins row,
the EVEN number pins row you will have to get to it from the bottom side of the board.
Since you can easily get access to pin1 (is also tied to pin 2) to verify if the 12Vdc is present or not first then we can go from there once I see your reading on pin1, black probe of the meter connected to the metal chassis of the TV with TV power switch activated.

[Snwboardr9876]

Re: Sharp LC-52LE640U - DET_PNL12V failure

Gotcha, okay that's how I figured it went. I have 12V at pin 1 when I hit the power button. Then once the standby light starts flashing I lose it.

[budm]

Re: Sharp LC-52LE640U - DET_PNL12V failure

OK, so the main board does send Panel POWER on signal to turn on the Q7120 to put out 12V to feed the PANEL 12V output pin 1 and pin 2.
So now you need to find out if the 12VDC is present at both ends of the SMD fuse with (ref to chassis GND) on the T-CON board.
Your picture of the T-CON board is way to blur for me to see the parts clearly.

[Snwboardr9876]

Re: Sharp LC-52LE640U - DET_PNL12V failure

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[Snwboardr9876]

Re: Sharp LC-52LE640U - DET_PNL12V failure

Are these the SMD fuses you're talking about? If so, when I hit the power button I have 12V at the top of the one with a red arrow but nothing at the bottom. Ofcourse I lose the 12V once the standby light starts flashing. I have no continuity on either the fuse with the red arrow and also the blue arrow but I do have continuity on the one in between them.


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[budm]

Re: Sharp LC-52LE640U - DET_PNL12V failure

FB4801 is Ferrite Bead inductor.

Some question, see the pictures.

[Snwboardr9876]

Re: Sharp LC-52LE640U - DET_PNL12V failure

And the other two with the arrows I drew? If either of them are not the fuses you were talking about then where is it?

[budm]

Re: Sharp LC-52LE640U - DET_PNL12V failure

See updated post 18.