Sharp lc-60le550u weird issue

[sputnikoff]

I have unit that had no power checked power supply voltage stby at 5vdc and replaced with spare i had,still same.Then i replaced the main board QPWBFX905WJZZ/KD342WJ board.The set fired up ok.I ran it for couple hours everything worked fine ,good picture all options ok.I power off and was going to replace cover turned it around for last test........now back to square 1 ,,,no power.Same problem i began with.

[budm]

Re: Sharp lc-60le550u weird issue

For us to help we will need good clear pictures of the whole backside of the TV showing all the boards, and the straight shot pictures of the whole top and bottom side of the power supply board so we can read the printed texts on the board.
It is hard to do long distant troubleshooting without seeing what we are dealing with.
What Voltages did you test so far on the power supply board connectors?

[sputnikoff]

Re: Sharp lc-60le550u weird issue

I have 2 spares of power supply so i took them out of working unit the display was struck so those were parts units.The spare main board worked for 3 hours and was believed to be working but gave up when i was about to put back on.The unit done a couple strange things before quitting i powered it several times and got sound for few seconds before it went out totally which leads me to question the led strips.I dont have led test strip so thats on list of must haves.The voltages are 4.96 vdc on pin 15 the one with black mark by connector in pic.picture 2.Thats it for voltages.I got it working with main board change out but its not working on that now.I definitely have rule out led strips.

[budm]

Re: Sharp lc-60le550u weird issue

https://www.badcaps.net/forum/attach...2&d=1526262183
There are 24 Pins on that PD connector, we need to know the Voltages of each pin except the GND pin.
Make sure to report the pin name and follow by the Voltage reading so we can easily see the power supply Voltages and the Control Voltages.

https://www.badcaps.net/forum/attach...4&d=1526262183
BTW: that PL connector, where does it go to on the other end of the connector?
That is why we need the pictures of the whole back side of the TV so we can see how the boards are connected together.

[sputnikoff]

Re: Sharp lc-60le550u weird issue

First of all bud thanks for all help.The only voltages i can get is 4.967vdc out of pin 15,the rest are 0vdc on that 24 pin connector.I like just rule out leds as possible problem what pins do i short.i was going to disconnect main board.I assume its 5 vdc and ps_on.

[budm]

Re: Sharp lc-60le550u weird issue

Pin 13: AC_DET (this is an error signal to tell the main board if the incoming AC Voltage is OK or not) needs to be about 3VDC otherwise the main board will stay in shutdown mode. The typical failure in the AC_DET circuit is due to either bad Opto-isolator or resistor network for driving the LED in the Opto have resistance drifted up.

[sputnikoff]

Re: Sharp lc-60le550u weird issue

Yes i double checked bud and once i saw 1.3 vdc there then went to 0vdc.I have 3 power supplies on hand so ruled out that as possibility.I removed connector from main board and jumper-ed 14 and 15 voltage on man cap came up to 398vdc .I checked across output for leds bur no voltage present however 85vdc across caps on output to 4 fields of leds.

[budm]

Re: Sharp lc-60le550u weird issue

You need to have that 3V at the AC_DET pin to tell the main board the incoming AC is OK.
So i do not understand this "Yes i double checked bud and once i saw 1.3 vdc there then went to 0vdc." AC_DET shows 1.3V and then it goes to 0V? That AC_DET signal is generated by the power supply board and this is common failure in these Sharp TV, there are many thread regarding to this problem. The 3V at AC_DET should be there as soon as the AC is applied to the power supply board.
You can remove the AC_DET wire from the power supply board and then connect 1K resistor between 5VSTBY and the end of that wire to fool the main board that the AC_DET is OK.