Sharp Aquos - LC-52LE640U - Power Supply Error

[wcsd106]

Re: Sharp Aquos - LC-52LE640U - Power Supply Error

Yes, bud. I was referring to the negative leg of the main filter cap.

Regardless, I'm still seeing about 9vac on the pnl12v pins when I use the chassis ground as gnd ref on the secondary side.

Correct me if I'm wrong, but shouldn't those output voltages be DC?

[budm]

Re: Sharp Aquos - LC-52LE640U - Power Supply Error

So you set your meter to AC and it shows the reading on the meter, if you have one of those cheap meter with just one diode to rectify the AC feeeding the meter, the meter will show reading even though the source Voltage is DC.
Set your meter to ACV and then try reading the batteries Voltage, then reverse the meter leads to see if you get the reading on then meter in this ACV mode.

[budm]

Re: Sharp Aquos - LC-52LE640U - Power Supply Error

Read about cheap meter when it is set to ACV mode and it shows Voltage reading when measure DC power source.
https://www.badcaps.net/forum/showth...how+Voltage+ac

[wcsd106]

Re: Sharp Aquos - LC-52LE640U - Power Supply Error

Very interesting read, Bud. Thanks.

This is the meter I'm using.. It's been my bench meter since my bench meter for years. It's a BK Precision 5460 True RMS 5-1/2 digit digital multimeter.

This morning I thought about what you mentioned, so I tested the meter while connected to my regulated DC power supply. The DC voltage scale on the meter shows the correct voltage, the AC scale shows ZERO when connected to DC.

I own some cheap "toolbox" meters like the harbor freight kind, but I don't use them on repair work. I paid a couple hundred dollars for the BK used several years ago.

I may not get to mess with the board too much today. I spent yesterday evening pulling up the carpets in our living room and today I'm going to be installing laminate flooring in that room. Tried to get some helpers, but all my buddies seem to disappear when it's flooring time.

[budm]

Re: Sharp Aquos - LC-52LE640U - Power Supply Error

So you have good meter which then I cannot see why you are getting AC readings on the PNL_POWER since the DC is generated by rectifing high frequency AC (50~100KHz range) which most meter does not have that high bandwidth to be able to measure it.
"I spent yesterday evening pulling up the carpets in our living room and today I'm going to be installing laminate flooring in that room." Can you take some pictures on how you are doing the floor? I would like to see what you have to put down (foam pads?) before installing the laminate.

[Terryfictv]

Re: Sharp Aquos - LC-52LE640U - Power Supply Error

If you do not have the 13.3v, that is the cause of the two/two blink code.

[budm]

Re: Sharp Aquos - LC-52LE640U - Power Supply Error

The SWITCHED panel power feeding the LCD PANEL is turned on by the command from the main board.
If I remember correctly, the PNL_PWR is the pin that receives the turn on command from the main board and the PNL_12V is the output pin. I need to look at the board lay out to verify.

[Terryfictv]

Re: Sharp Aquos - LC-52LE640U - Power Supply Error

Hi All,
I fixed an LC-60LE640U today...set was dead. D7805 shorted, replaced with
MUR460.

[budm]

Re: Sharp Aquos - LC-52LE640U - Power Supply Error

Hi All,
I fixed an LC-60LE640U today...set was dead. D7805 shorted, replaced with
MUR460.

That Diode is for the PFC Boosted Voltage PFC diode, when that is shorted out you will not have Boosted Voltage. The MURxxx Diode used in the SAMSUNG TV also have this same failure mode.
https://www.badcaps.net/forum/showth...460#post561399

600V rating is on the low side, it should have been 1000V.
https://cdn.badcaps-static.com/pdfs/...9c4e18487c.pdf

[wcsd106]

Re: Sharp Aquos - LC-52LE640U - Power Supply Error

I'm back.. Projects breed projects, I've learned. Floor install went OK.. I won't use that particular brand of flooring again though. (Style Selections SwiftLock Lowes House Brand) but that's another story altogether.

Bud, I took some photos for you while I was installing it. There's not much to do, lay a row of underlayment and then lay your flooring down on top of it.

Now moving on to the TV...

I managed to get my hands on a supposedly good power supply board to do some testing with. I installed it in the defective TV, and it has cleared my 13v blink code, but when I turn the TV on, the little chevron at the bottom lights up but nothing ever shows up on the screen.

As far as the other board goes, I haven't tried testing voltages while it is in circuit. Finally made it to my weekend and have been overwhelmed with eBay orders since last week, so I am finally able to break away and do some repair and troubleshooting.

[wcsd106]

Re: Sharp Aquos - LC-52LE640U - Power Supply Error

*Bump*

Any ideas or suggestions on how to proceed with further testing?

After installing a new power supply board, the TV now powers up, but nothing is visible on the screen.

[wcsd106]

Re: Sharp Aquos - LC-52LE640U - Power Supply Error

*Update*

Pressing the lcd bezel just above the aquos logo resulted in a quick popping sound and then the tv started working again.

Directly behind where I pressed was the two ribbon cables running from the TCON to the LCD/LEDs

I have reseated those cables and the tv appears to be functioning correctly.

My question is now, should I replace those ribbon cables or just assume they were not seated properly?

[bezbor]

Re: Sharp Aquos - LC-52LE640U - Power Supply Error

can you send manual link for sharp lc-52le640u power board

[budm]

Re: Sharp Aquos - LC-52LE640U - Power Supply Error

http://elektrotanya.com/?q=showresul...oria=&kat2=all