Author Topic: sharp lc-60le640u Backlight but no video or sound. (Read 380 times)

Hornnumb2 · « **on:** February 13, 2019,17:42:30 »

Working on this unit, I have check voltage to main board and are getting the 13 & 3 and 5 volts. I have check voltage to t con board and get 12v on first 2 and zero on last 2 pins. The unit does power on and has backlight but no Video or sound. I was just getting backlight but I have messed with ribbon cables on t con board and now I get some red lines on left side of screen.

Mulja tv repair portal · « **on:** February 13, 2019,17:42:30 »

downunder · « **Reply #1 on:** February 14, 2019,02:36:05 »

See if your problem is per attachment. The 2 flat white flexies at the bottom of your picture - are these what you messed with?

Clean the contacts on these and make sure they're seated properly in the sockets, especially the one on the right. Bruce

Hornnumb2 · « **Reply #2 on:** February 15, 2019,10:43:25 »

I did test the panel by removing one ribbon at a time. half screen white and other black and vice versa. So I think that shows the panel is good right? I just get backlight but no video or menus. The green light flashes on the main board should it be constant? Thanks

Mulja tv repair portal · « **Reply #2 on:** February 15, 2019,10:43:25 »

Hornnumb2 · « **Reply #3 on:** February 15, 2019,22:05:19 »

Replaced t-con for no change except to clear up the red line I caused, back to backlight but nothing else. I got some more reading from top of powerboard.
1- 12.1v. PNL 12v
3- -.009 GND
5- 13.1v UR 13.2v
7- 13.1v. UR 13.2v
9- .010. GND
11- .010. GND
13- 3.31v. AC_DET
15- 5.04v. BU 5v
17- 1.15v. PWM1
19- 1.3v. Dimmer
21- 1.15v. OFL
23- .000v. PWM2

Any suggestions from that, I can check the readings on the bottom if needed. I am not sure about 17 and 23. Thanks

downunder · « **Reply #4 on:** February 16, 2019,04:11:34 »

Those voltages are all normal. PWM1/2 are to do with the backlights which you say are on. T-con has been changed. Can't see the power supply causing it.

So it's starting to look like main board. I'll upload the service manual to quuq. Bruce

Hornnumb2 · « **Reply #5 on:** February 16, 2019,22:40:03 »

Thanks Bruce, main board on way.

Mulja tv repair portal · « **Reply #5 on:** February 16, 2019,22:40:03 »

Hornnumb2 · « **Reply #6 on:** February 19, 2019,22:27:34 »

Well installed main board today with no change, I have a shop jimmy kit to rebuild power supply. I just know where to go from here. Thanks Michael

downunder · « **Reply #7 on:** February 20, 2019,02:41:01 »

OUCH! bum steer - sorry about that Michael, but that's the way of it in this industry. Ah well, soldier on. Bruce

Hornnumb2 · « **Reply #8 on:** February 20, 2019,15:06:00 »

Any next step to take?

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