Sharp LC-52D65U won't power on

[J32259]

Hello All,

Thank you for your help in advance.

I have a Sharp LC-52D65U that will not turn on. If power button is pressed, the TV will not turn on.

I will try to outline steps taken so far to troubleshoot and resulting conditions.

Initial mains power applied (plug TV power cord into wall socket) = Power LED blinks green at ~1 Hz rate constantly. No other front panel indications.

Try Sharp reset procedure (Volume down + Input buttons pressed at same time while mains power applied) = Set will turn on and show a possible channel for ~2 seconds then an audible "click" can be heard at the same time the screen goes totally black.

I'm attaching pictures of the set with the back cover removed.

I have a multimeter and soldering iron available.

Appreciate any advice on further troubleshooting.

[budm]

Re: Sharp LC-52D65U won't power on

There are pin names for each one of those white connectors on the power supply board, you need to report the DC Voltage readings of the pins of those connectors, you MUST put down the pin names and follow by the Voltage reading so we easily see what they are.

[RJARRRPCGP]

Re: Sharp LC-52D65U won't power on

Looks like it's CCFL-based...

That means a bad CCFL bulb, bad inverter transformer, bad CCFL connection or bad caps (doesn't look likely, in comparison to the preceding-3)

[budwich]

Re: Sharp LC-52D65U won't power on

what happens when you press menu once you have tried the "force sequence" to start the set?

further you can try firmware update using a usb stick and see if it takes. NOTE you likely have to format the stick as fat16 for it to work.

[J32259]

Re: Sharp LC-52D65U won't power on

Thank you for quick responses budm, RJARRRPCGP and budwich!

budm - Please see voltages with unit plugged in and power light flashing (after screen goes dark)

LB1(US)
Pin 1: INV1 = 0V
Pin 2: INV2 = 0V
Pin 3: INV3 = 0V
Pin 4: INV4 = 0V
Pin 5: INV5 = 0V

PD(US)
Pin 1: 13.5V (SIGNAL) = 0V
Pin 2, 3: 13.5V (AUDIO) = 0V
Pin 4, 5: SGND (AUDIO) = 0V
Pin 6, 7: SGND = 0V
PIN 8: AC_DET = 3V
Pin 9: PS_ON = 0V
Pin 10: PNL_POW = 0V
Pin 11: SGND = 0V
Pin 12: BU5V = 5V

PL
Pin 1: PNL12V = 0V
Pin 2: PNL12V = 0V
Pin 3: SNGD = 0V
Pin 4: SNGD = 0V

LR1
Pin 1: INV60V = 0v
Pin 2: SGND = 0v
Pin 3: INV12V = .144v

LB2(US)
Pin 1: INV1 = 0V
Pin 2: INV2 = 0V
Pin 3: INV3 = 0V
Pin 4: INV4 = 0V
Pin 5: INV5 = 0V

Voltages with Volume down and Input buttons pressed (force on) and screen lit

LB1(US)
Pin 1: INV1 = 0V
Pin 2: INV2 = 3.2V
Pin 3: INV3 = 0V
Pin 4: INV4 = 3V
Pin 5: INV5 = 3.4V

PD(US)
Pin 1: 13.5V (SIGNAL) = 13V
Pin 2, 3: 13.5V (AUDIO) = 13V
Pin 4, 5: SGND (AUDIO) = 0V
Pin 6, 7: SGND = 0V
PIN 8: AC_DET = 3V
Pin 9: PS_ON = 3V
Pin 10: PNL_POW = 3.3V
Pin 11: SGND = 0V
Pin 12: BU5V = 5V

PL
Pin 1: PNL12V = 12V
Pin 2: PNL12V = 12V
Pin 3: SNGD = 0V
Pin 4: SNGD = 0V

LR1
Pin 1: INV60V = 61v
Pin 2: SGND = 0v
Pin 1: INV12V = 11.86v

LB2(US)
Pin 1: INV1 = 0V
Pin 2: INV2 = 3.3V
Pin 3: INV3 = 0V
Pin 4: INV4 = 3.0V
Pin 5: INV5 = 3.4V


RJARRRPCGP - Please see voltages above on INV 1 and INV 3.
I agree as all the caps physical condition looks OK.

budwich - If I press the Menu button after Volume down And Input buttons are both pressed, nothing different happens. TV still turns off and power LED flashes constant green. I don't believe the power is on long enough to perform any upgrade. Appreciate the hint on Fat16

[J32259]

Re: Sharp LC-52D65U won't power on

Found LB1 and LB2 (US) Pin1 short to ground even with all connectors unplugged.

Does anyone have a schematic for RDENCA295WJQZ DPS-277BPA? This is the power board on my set.

[J32259]

Re: Sharp LC-52D65U won't power on

OK I must be going crazy. I just checked Pin 1 again and it is not shorted now. I checked several times the last time. Schematic would still be very helpful.

[freakaftr8]

Re: Sharp LC-52D65U won't power on

When you for start the TV and you see the channel show up for a few seconds to see any pink bars in the screen? Sharp had a problem with CCFL's burning out prematurely

[budwich]

Re: Sharp LC-52D65U won't power on

service manual for the set is available as I worked on a 42 in unit before xmas... I am not at my internet so I don't know where I found it but its around in the usual places.

as far as the power board, most are not available anywhere as the manufacturer doesn't include them in their service manual.

[J32259]

Re: Sharp LC-52D65U won't power on

freakaftr8 - No pink bars visible.

budwich - I found a copy of the service manual online. I've sent an email to Delta customer service to see if they will provide a schematic.