Sharp LC-60LE633U Inverter output voltages

[organman]

Greetings, I have a Sharp LC-60LE633U when powered up only the V light comes on. I have checked the LED strips and they all light up. When the LED's are plugged into the PS board I get an output voltage of 74v DC. If I unplug the LED's the output voltage on the PS is 184v DC. Does this indicate a weak PS?
Thanks

[organman]

Re: Sharp LC-60LE633U Inverter output voltages

My fellow Techs, does anyone have any information with this TV issue?
Thanks

[R_J]

Re: Sharp LC-60LE633U Inverter output voltages

You likely have a bad led in one of the strings in the panel, led testers are not reliable for testing a complete string, they only output around 30ma of current, and the leds can fail at higher currents supplied by the power supply, the low voltage is due to the boost circuit shutting down due to its protection circuit, the high voltage you read without the leds connected is just the caps being charged to peak voltage without any current being drawn.

[Diah]

Re: Sharp LC-60LE633U Inverter output voltages

You likely have a bad led in one of the strings in the panel, led testers are not reliable for testing a complete string, they only output around 30ma of current, and the leds can fail at higher currents supplied by the power supply, the low voltage is due to the boost circuit shutting down due to its protection circuit, the high voltage you read without the leds connected is just the caps being charged to peak voltage without any current being drawn.

+1
we did covered this issue at Sharp LC 70 from user was from Singapore .. how to test PWB stand alone and BL with out dummy LED tester

[organman]

Re: Sharp LC-60LE633U Inverter output voltages

Thank you for this valuable info.

[organman]

Re: Sharp LC-60LE633U Inverter output voltages

I'm getting 1 long and 1 short blink code, I have checked all 4 LED strips and all LEDs are bright. My tester shows the strips will light up at 85 volts. When I perform the reset the TV will power up but there is no backlight. The LED output from the PS is 74.6 volts. Shouldn't that voltage be higher? I have looked at other threads and have not found where this problem has been addressed. Has anyone had this problem and was able to determine how to correct it? Thanks

[organman]

Re: Sharp LC-60LE633U Inverter output voltages

Does anyone have the LED output voltages for this power supply board? RUNTKA848WJN1
Thanks

[CapLeaker]

Re: Sharp LC-60LE633U Inverter output voltages

You can put all kinds of voltage on there as much as you want, LED’s are current controlled! I point you at post #3 again. LED’s can fail in a weird way were they can measure or test “good” but under load fail miserably. If you are good you can try to override the backlights protection. But this is for testing only.