sharp lc-65ub30u plays but screen is flashing on and off

[JunkmanJimbo]

Hey guys! It has been awhile since I've been on here. I hope everyone is doing well. I just picked up this Sharp lc-65ub30u. It plays but the screen is flashing on and off. Other than that i seems to be a great tv. Any ideas what the problem might be? I haven't pulled the back off yet. I thought I would get some opinions first. Thanks in advance for any help you can offer.

[Diah]

no way the screen will flashing on & off... but the BL will do,, open it and show us the boards

[JunkmanJimbo]

Here's pictures of the boards. The backlights are flashing on and off. Thinking it might be a bad power supply. What's your opinion?

[Diah]

go to setting ,menu and reduce the BL level to 30% . see if remain on

[JunkmanJimbo]

This Sharp TV backlight settings are from +16 to -16. I set them all the way to -16 and nothing changed.

[Davi.p]

My ipotesis is that one or more sector power transistor led driver is not ok, the reason? The electrolitic caps i guess no, set is too.young, maybe all sector leds are gone, i dont think so, maybe controlling big IC has to be solder renewed because they driven bad those..

[Diah]

This Sharp TV backlight settings are from +16 to -16. I set them all the way to -16 and nothing changed.

you have bad one or more shorted led... give attention on screen you will see some shadow on rand when it goes off& on

[JunkmanJimbo]

Actually I don't see any shadows on the screen. Not saying they're not there but from what I can see the picture looks great except for the flashing. So, do you still think my problem is still the backlights? Is there any way it could be the LED driver board that's mounted on the power supply? Thanks for your help. If you still feel like it's the backlights I will pull the screen to check them but I probably can't do thet until Monday or Tuesday. Thanks again!

[Diah]

Actually I don't see any shadows on the screen. Not saying they're not there but from what I can see the picture looks great except for the flashing. So, do you still think my problem is still the backlights? Is there any way it could be the LED driver board that's mounted on the power supply? Thanks for your help. If you still feel like it's the backlights I will pull the screen to check them but I probably can't do thet until Monday or Tuesday. Thanks again!

disconnect the yellow cable socket from LED driver boards which it come from Main boards and turn on tell the result

[JunkmanJimbo]

Thanks Diah. It might be a few days so I will tell you the result then. Thanks again!

[Davi.p]

i.was meaning bad power transistor on the blue board...simply..

[JunkmanJimbo]

disconnect the yellow cable socket from LED driver boards which it come from Main boards and turn on tell the result

Hey Diah. I decided to pull the yellow cable today. When I pulled the yellow cable between the LED driver board and the mainboard the backlights would not come on. When I plugged the cable back in the backlights still wouldn't come on. I had to unplug the power cord and plug it back in for the backlights to come back on, still blinkiing. What's your opinion on this? Thanks!
Something else I noticed.....when I turn the power off by the power button the backlights contnue to flash for another 20 seconds before they turn off.

[JunkmanJimbo]

i.was meaning bad power transistor on the blue board...simply..

Can you tell me which one is the power transistor? Thanks!

[Davi.p]

No is not one, there are many all identical, you have to find which one suffers if any

[JunkmanJimbo]

No is not one, there are many all identical, you have to find which one suffers if any

I checked all the transistors and all of them appear to be good.

[Diah]

Hey Diah. I decided to pull the yellow cable today. When I pulled the yellow cable between the LED driver board and the mainboard the backlights would not come on. When I plugged the cable back in the backlights still wouldn't come on. I had to unplug the power cord and plug it back in for the backlights to come back on, still blinkiing. What's your opinion on this? Thanks!
Something else I noticed.....when I turn the power off by the power button the backlights contnue to flash for another 20 seconds before they turn off.

first don't follow other with his confusion, as usual irresponsible technician clarification

use yours DM in DC mode measure each channel of LED at start up you have 4 each have LED + & LED -
or try to unplug one channel at time.

[JunkmanJimbo]

first don't follow other with his confusion, as usual irresponsible technician clarification

use yours DM in DC mode measure each channel of LED at start up you have 4 each have LED + & LED -
or try to unplug one channel at time.

I unplugged each of the 4 connectors of the LED cables one at a time. The backlights still blinked off and on. I tried unplugging all 4 and then there were no backlights.
But why would the backlights stay on for another 20 seconds after I power off the TV?

[Diah]

I unplugged each of the 4 connectors of the LED cables one at a time. The backlights still blinked off and on. I tried unplugging all 4 and then there were no backlights.
But why would the backlights stay on for another 20 seconds after I power off the TV?

stay on for 20 seconds or it remain flashing for 20 seconds after you put it in STBY.=

if remain ON for 20 seconds.... we need to tray log in first in service menu and do clear chip as hard reset... to avoid any mistake at BL_ON signal send BY MB.

also take out the power boards and the LED driver boards and inspect the down side of cracking joint solder

[Diah]

when there are open circuit at discharging power boards or ceramic cap changed value this will happen.

[JunkmanJimbo]

stay on for 20 seconds or it remain flashing for 20 seconds after you put it in STBY.=

if remain ON for 20 seconds.... we need to tray log in first in service menu and do clear chip as hard reset... to avoid any mistake at BL_ON signal send BY MB.

also take out the power boards and the LED driver boards and inspect the down side of cracking joint solder

The backlights remain flashing for 20 seconds after powering the TV off.