Vizio E70U-D3 - No Backlight

[hardbox]

Vizio E70U-D3 - No Backlight

Customer brought in for has sound, no picture or backlights. Replaced the backlights with set from SJ and the backlights still doesn't turn on. Made sure everything was connected and they are working. Pins 1-5 at CN201 on PS which are the LED_OUTPUTS are reading 0 volts, however am getting the 16 V to main and can see image with flashlight. Also not getting any voltage from main to LED's at CN403. What could cause this?

https://www.shopjimmy.com/vizio-y838...or-e70u-d3.htm

https://www.shopjimmy.com/vizio-09-7...-led-board.htm

Power Supply / LED Board: 09-70CAR090-00

Mainboard: Y8387136S

[nomoresonys]

Re: Vizio E70U-D3 - No Backlight

Do test #3 below.

[hardbox]

Re: Vizio E70U-D3 - No Backlight

CN201 - Same voltages when off and on for all pins. Indicator light on front of TV changes when I press power. Dark image in background visible with flashlight.

1. VSNS - 0 V
2. LED_OUT - 0V
3. LED_OUT - 0V
4. LED_OUT - 0V
5. LED_OUT - 0V
6. GND
7. GND
8. GND
9. GND
10. GND
11. 16VS - 16V
12. AC-DET - 3.8 V
13. PS-ON - 4.9 V
14. 16VS - 16V
15. 16VS - 16V

[nomoresonys]

Re: Vizio E70U-D3 - No Backlight

Check voltage of C1 and C2, put meter on 200 vdc or next one up, positive probe on positive + leg, negative probe on negative - leg, check with power off and with power on, careful not to touch anything with your hands, this is the HOT/DEADLY side of powerboard.

[hardbox]

Re: Vizio E70U-D3 - No Backlight

C1 and C2 both show 167.6 V when on. Then both show 165.4 V when OFF.

[nomoresonys]

Re: Vizio E70U-D3 - No Backlight

.

[nomoresonys]

Re: Vizio E70U-D3 - No Backlight

Looks like your not getting your boosted pfc voltage when tv is on, think it should be around 400 volts when on.

[hardbox]

Re: Vizio E70U-D3 - No Backlight

Hmm. Getting 0 Volts DC on each side of TCON fuse (F100). *edit* Nevermind, my red probe wasn't placed well. Am getting 12 V both sides.

[hardbox]

Re: Vizio E70U-D3 - No Backlight

So the problem is located on the Power Supply most likely for lack of PFC voltage?

[nomoresonys]

Re: Vizio E70U-D3 - No Backlight

Seems like it, did you check all the diodes on powerboard?

[hardbox]

Re: Vizio E70U-D3 - No Backlight

D103 and D107 are reading short, will test out of circuit

[hardbox]

Re: Vizio E70U-D3 - No Backlight

oh, D107 tests good out of circuit, D103 reads short.

[nomoresonys]

Re: Vizio E70U-D3 - No Backlight

Ok, that may be the only problem.

[budm]

Re: Vizio E70U-D3 - No Backlight

PFC Diode D103 and D107 are connected in parallel, so you found the cause of not having PFC boosted Voltage.

[hardbox]

Re: Vizio E70U-D3 - No Backlight

Replaced D103 SF50JG (600V 5A) with MUR460 (600 V 4 A rectifier). This fixed the problem. Thank you!

[nomoresonys]

Re: Vizio E70U-D3 - No Backlight

Glad to hear it.

[budm]

Re: Vizio E70U-D3 - No Backlight

Did you replace both of them? They are connected in parallel so both of them should be the same so to match Vf as close as possible.