Sharp Aquos LC-40D68UT Blinking Red Power Light

[dhoff024]

Its been a while since I last posted anything and everyone on here is always a great help at troubleshooting these TV issues. I am by no means an expert when it comes to this stuff but I am handy enough that I can follow the directions of the more versed members on this forum. Now some people may think that I am crazy (I know my wife does haha). Yesterday I was walking my dog and I noticed one of my neighbors had a box out for the trash for a new TV. I didn't really think much of it until I was walking back and noticed their old LCD sitting out for the trash as well, so I grabbed it and figured it would be a nice free TV to work on and see if I could get it fixed and if not then it was no big deal really. The TV was slightly wet from sitting outside so I dried it off and let it sit overnight. I came home from work tonight and tore the back off the TV to see if I noticed any moisture or anything out of the ordinary or anything that jumped out. I did not so I proceeded to plug the TV in. When I plugged the TV in I got a blinking red power light. I did some searching and some people were saying there are some different button combinations that you hold down when you plug it back in so I figured I would try those first because those were the easiest things to try first. I held down the volume up and power and got a green light for a short period of time, but nothing came on the screen and it went back to flashing red. I am now at a point where I don't know what the next step should be. I don't see any bulging caps so I don't really know where to go from here. Any help is greatly appreciated. Hopefully with everyone's help I can bring this one back from the dead haha.

[dhoff024]

Re: Sharp Aquos LC-40D68UT Blinking Red Power Light

Adding pictures of the boards on the back of the tv

[dhoff024]

Re: Sharp Aquos LC-40D68UT Blinking Red Power Light

Bump

[budwich]

Re: Sharp Aquos LC-40D68UT Blinking Red Power Light

start by verifying / recording all the voltages that are printed on the boards (power, tcon, main) usually in and around the connectors. Go from there.

you can try disconnecting the tcon and see what happens (probably not much). Further there are fuses on most tcons, check them.

[dhoff024]

Re: Sharp Aquos LC-40D68UT Blinking Red Power Light

Thank you for the reply. This may sound stupid but the other TV's that I fixed I didn't have to record any voltages or anything just replace bad caps and some other things that needed replaced. Is there any way you could tell me the proper way to record the voltages. I know how to use a multimeter just don't know the proper way to check the voltages. I also don't know all the abbreviations for the different boards or there functions. Is there anywhere you can direct me to get this information or could you tell me how to do this? Thanks again for all the help

[dhoff024]

Re: Sharp Aquos LC-40D68UT Blinking Red Power Light

Redirecting an old thread of mine. This tv has been sitting in my garage since I posted this. I was just able to successfully fix a tv I found thanks to everyone's help so I am focusing back on this TV to see if I can get it working or if not dispose of it. I will take as many of the voltages as I can and report back. I did disconnect the tcon as suggested before with no change still a blinking red power light. When you press the power nothing happens just still blinks.

[dick_barton]

Re: Sharp Aquos LC-40D68UT Blinking Red Power Light

Set your meter to DC volts and measure the voltages on the pins of the connectors with the red probe and black probe on metal chassis.
There should be a name alongside each pin of the connector
eg
CN751
Pin number, legend, voltage
Pin 1, P_ON, 4.3V
Pin 2, DIM, 2.8V
Pin 3, 5VSTB, 4.8V
etc.

[dhoff024]

Re: Sharp Aquos LC-40D68UT Blinking Red Power Light

Set your meter to DC volts and measure the voltages on the pins of the connectors with the red probe and black probe on metal chassis.
There should be a name alongside each pin of the connector
eg
CN751
Pin number, legend, voltage
Pin 1, P_ON, 4.3V
Pin 2, DIM, 2.8V
Pin 3, 5VSTB, 4.8V
etc.

Thank you dick_barton when I was initially doing this TV I wasn't sure how to properly test the voltages but I learned a lot from the last TV I just fixed. Using your photo with the connectors highlighted, the connector at the top reads like this.

GND-0
PNL-0
POW-0
Bus5v- 5V
Pson- 3V
ACDET-0
INV4-0
INV3-0
INV2-0
INV1-0

12V-0

Bottom Connector:

24V-0
GND-0
INV1-0
INV2-0
INV3-0
INV4-0

I also took the voltage readings of the connector from the power supply to the main board. I got a 0 reading from all pins besides the 4th pin from the left on this connector read 5V. The only other connector that I got any voltage reading on was the connector from the button panel to the main board. There are 4 pins the first pin going from left to right was 0, the next was 3.3V, and the next 2 read 3.2V. I got a 0 reading from all other connectors on the board. Any help from here is greatly appreciated.

[dick_barton]

Re: Sharp Aquos LC-40D68UT Blinking Red Power Light

I'm a little confused here. One connector has 14 positions with only 13 wires connected so doesn't match up with your table above. The second connector at the top of the picture also has 14 position of which 2 are not connected.

Connector xxxx (photo post#7 top connector)
Pin1
Pin2
.....etc.
Pin12
Pin13
Pin14

Connector yyyy (photo post#7 bottom connector)
Pin1
Pin2
......etc.
Pin 13
Pin14

[dick_barton]

Re: Sharp Aquos LC-40D68UT Blinking Red Power Light

CN4771
Pin 1,2,3,4,5, [24V]...........0V
Pin 6,7,8,9,10, [GND]
Pin 11, [INV1]..................0V
Pin 12, [INV2]..................0V
Pin 13, [INV3]..................0V


CN751
Pin1,2, [12V]............0V
Pin3, [INV1].............0V
Pin4, [INV2].............0V
Pin5, [INV3].............0V
Pin6, [INV4].............0V
Pin7, [AC_DET].........0V
Pin8, [PS_ON]..........3V
Pin9, [BUS5V]..........5V
Pin10, [POW]...........0V
Pin11, [PNL]............0V
Pin12,13,14, [GND]



If you disconnect the mainboard and power up the set do the backlights come on.

[budm]

Re: Sharp Aquos LC-40D68UT Blinking Red Power Light

Are the Voltage readings with all the connector in place?
"ACDET-0" If that is true reading with all the connectors in place then it is not normal, it should be >2V if I remember it correctly, this will cause the main board not to send out the command signal to turn on the power supply because it thinks the incoming AC to the the TV is not in the operating range. The common cause of the bad AD DET is sue to bad Opto-isolator or the resistors network for the incoming AC sensing circuit.

[dhoff024]

Re: Sharp Aquos LC-40D68UT Blinking Red Power Light

CN4771
Pin 1,2,3,4,5, [24V]...........0V
Pin 6,7,8,9,10, [GND]
Pin 11, [INV1]..................0V
Pin 12, [INV2]..................0V
Pin 13, [INV3]..................0V


CN751
Pin1,2, [12V]............0V
Pin3, [INV1].............0V
Pin4, [INV2].............0V
Pin5, [INV3].............0V
Pin6, [INV4].............0V
Pin7, [AC_DET].........0V
Pin8, [PS_ON]..........3V
Pin9, [BUS5V]..........5V
Pin10, [POW]...........0V
Pin11, [PNL]............0V
Pin12,13,14, [GND]



If you disconnect the mainboard and power up the set do the backlights come on.

Disconnecting the mainboard and powering up does nothing but shut the red blinking LED off. I get nothing else happening from the TV.

[dhoff024]

Re: Sharp Aquos LC-40D68UT Blinking Red Power Light

Are the Voltage readings with all the connector in place?
"ACDET-0" If that is true reading with all the connectors in place then it is not normal, it should be >2V if I remember it correctly, this will cause the main board not to send out the command signal to turn on the power supply because it thinks the incoming AC to the the TV is not in the operating range. The common cause of the bad AD DET is sue to bad Opto-isolator or the resistors network for the incoming AC sensing circuit.

I will double check all the readings again and let you know to make sure. The readings I took were with all connectors in place.

[Scollins]

Re: Sharp Aquos LC-40D68UT Blinking Red Power Light

Did you do anything to figure it out?