Sharp Aquos Quattron LC-52LE810UN power cycle odd issue

[ChrisCopper]

hey guys,

Ive been a long time lurker, I am a repair tech and I like to help people out when I can.

I have the above said set, given to me from a frustrated customer who has had it into 3 different shops and no joy on the repair. pretty odd I thought.

anyway, the symptom is as follows.

when the set is totally cold, it fires on no problem and will stay lit sometimes for up to 5 full mins , sometimes more sometimes less. then it starts power cycling. When it cycles the led light and shut down. There is no real code happening here, the set just power cycles every 15 to 20 seconds and tries to start with no joy.

i have the set fully apart and the lcd panel removed. i can see any issues with the led wiring. if I dont try to start the set the stby is correct 3.3vdc and is sitting there.

if i unplug the lamps i get the 1 long 1 short error code, but when I plug them in it just repeats the behavior.

so, any tips? ive looked over the power supply, nothing is getting hot, caps seem fine, esr levels are all good, and capacitance also seems fine. This does seem like a capacitor issue to me thats for sure so Im wondering if i should change them anyway just to see. other than that I cannot find a single thing wrong at the point.

any help appreciated if anyone has seen this before.

cheers,

chris

[maxvalutech]

Re: Sharp Aquos Quattron LC-52LE810UN power cycle odd issue

Surely sounds like a dry joint but the guys will need photos etc to respond properly.

[R_J]

Re: Sharp Aquos Quattron LC-52LE810UN power cycle odd issue

I guess you could try disconnecting the lvds cable from the t-con and see if the tv stays on, I know some of the panels have problems with the drive ic's that are on the panel ribbons on the side, I have seen one where one of the ic's would get hot and sht down the tv.

[ChrisCopper]

Re: Sharp Aquos Quattron LC-52LE810UN power cycle odd issue

well I have the panel totally dis connected and the lights are acting the same.

it sure seems like solder on an IC or something. I guess a question would be, is there a particular IC that could control these led , then over heat and act up?

[budm]

Re: Sharp Aquos Quattron LC-52LE810UN power cycle odd issue

Need to see the pictures of the whole back side of the TV showing how all the boards are connected together, that will a starting point.

[dskall]

Re: Sharp Aquos Quattron LC-52LE810UN power cycle odd issue

I think I would apply some freeze spray around the mainboard.

[ChrisCopper]

Re: Sharp Aquos Quattron LC-52LE810UN power cycle odd issue

here are a few pics. have everything connected but the panel itself and it behaves the exact same way.

I'm almost positive it's a thermal issue I'm just not sure what chips would make the set behave this way.

I'm thinking the freeze spray is a good idea as well.

[ChrisCopper]

Re: Sharp Aquos Quattron LC-52LE810UN power cycle odd issue

here is a better pic of board layout.

[ChrisCopper]

Re: Sharp Aquos Quattron LC-52LE810UN power cycle odd issue

anyone have any idea? I'm pretty sure I have a cold joint on an IC on the main board but my question is which one?

[rievax_60]

Re: Sharp Aquos Quattron LC-52LE810UN power cycle odd issue

A similar model has a common fault that affects the AC_DET. If it also uses an opto-coupler for the AC_DET try heating it.

[ChrisCopper]

Re: Sharp Aquos Quattron LC-52LE810UN power cycle odd issue

A similar model has a common fault that affects the AC_DET. If it also uses an opto-coupler for the AC_DET try heating it.

ok I'll look into this!!

[280zx]

Re: Sharp Aquos Quattron LC-52LE810UN power cycle odd issue

I have the same set with the same problem. When I got it it had no power to the unit so I replaced the power supply. Now it turn on for about 4-5 minutes then turns off. After a few it turn on again and repeats the on and off cycle. Do you figure it out?

[280zx]

Re: Sharp Aquos Quattron LC-52LE810UN power cycle odd issue

I have the same set with the same problem. When I got it it had no power to the unit so I replaced the power supply. Now it turn on for about 4-5 minutes then turns off. After a few it turn on again and repeats the on and off cycle. I also noticed that the power button on the set does not work. Did you figure it out?

[kgavionics]

Re: Sharp Aquos Quattron LC-52LE810UN power cycle odd issue

I have the same set with the same problem. When I got it it had no power to the unit so I replaced the power supply. Now it turn on for about 4-5 minutes then turns off. After a few it turn on again and repeats the on and off cycle. I also noticed that the power button on the set does not work. Did you figure it out?

Does the front led flashes before the tv goes off? if yes !how many times does it flash?

[280zx]

Re: Sharp Aquos Quattron LC-52LE810UN power cycle odd issue

No flashing lights. I turned it on and it worked for 3 minutes and turn off. After 3 minutes it turns on for 10 seconds and then cycles on and off every 5 seconds. I'm able to get the menu screen during the on cycle.

[280zx]

Re: Sharp Aquos Quattron LC-52LE810UN power cycle odd issue

Update TV runs for 3 minutes then turns off. At this point it tries to come back on every 5 seconds. At the 3 minute mark it come on for 3 minutes and keeps repeating the process.

[nomoresonys]

Re: Sharp Aquos Quattron LC-52LE810UN power cycle odd issue

If you can find a backlight NOT brightness setting try turning it down see if tv stays on longer if not turn it up and see what it does.

[280zx]

Re: Sharp Aquos Quattron LC-52LE810UN power cycle odd issue

Lowered backlight setting all the way and now TV runs for 14 minutes then turns off. At this point it tries to come back on every 5 seconds. At the 1 minute mark it came on for 14 minutes again and keeps repeating this process. When I turned the backlight setting all the way up TV ran for 8 minutes then turns off. At this point it tries to come back on every 5 seconds. At the 1 minute mark it came on for 8 minutes again and keeps repeating this process.

[nomoresonys]

Re: Sharp Aquos Quattron LC-52LE810UN power cycle odd issue

Backlight problem, you probably need to replace the backlight strips.

[280zx]

Re: Sharp Aquos Quattron LC-52LE810UN power cycle odd issue

Wouldn't I get sound during the time it goes off if it was the backlights?