Sharp Aquos LC52SE94U hit by surge

[selldoor]

Re: Sharp Aquos LC52SE94U hit by surge

Pictures are not clear enough for troubleshooting - probably need more light.

[budm]

Re: Sharp Aquos LC52SE94U hit by surge

Credit shopjimmy for the pictures: The main bridge rectifier should be check.

[Fwrothy]

Re: Sharp Aquos LC52SE94U hit by surge

Bridge tested: 4@~515

The part is a D25XB60

Still on the hunt for schems for this board(RDENCA235WJQZ) went to tomsservicemanuals looked at several Sharp models cross referenced by shopjimmy... Nada

Does anyone have any suggestions on where to look next?

[budm]

Re: Sharp Aquos LC52SE94U hit by surge

Use the lamp in place of the fuse to see if the lamp will stay on bright.

[Fwrothy]

Re: Sharp Aquos LC52SE94U hit by surge

Is this to just establish standby? Does the board have to be reinstalled. If the lamp stays bright then disconnect immediately?
What's the reason for a 75w lamp why not a 60 or 100?

[budm]

Re: Sharp Aquos LC52SE94U hit by surge

60~100W will be fine too, the main key is that the lamp should not stay bright when you apply the power to the TV without activating the power switch, it should flash brightly then dim down, if it stays bright, it means you still have short circuit, at the same time when the lamp stays bright it will limit the voltage applied to the TV so no further damage will be doen to the TV since most voltage will appear on the lamp.

[tom66]

Re: Sharp Aquos LC52SE94U hit by surge

Thanks, that's a great reference but unfortunately it looks like that model has a RDENCA231WJQZ board-my board is an RDENCA235WJQZ- similar but I doubt the same. I will keep looking around, thanks again!

It looks identical to my PSU board, so it should be close enough. The only difference to me is a missing filter choke probably for the US version, the EMI restrictions are lesser there maybe.

[Fwrothy]

Re: Sharp Aquos LC52SE94U hit by surge

Tom, it is the exact same physical board, if you notice the stamp on the board, the check boxes include 231-235-237. I'm totally game to try this approach after all u know way more than I do. I started down the path from input with this schem everything I saw so far matched-incidentally do u see where the relay is? I've checked the bridge and noodled around some of the power devices but that it. can u point me down the path or do I need to try powering up again as suggested ?

Budm, I was so excited by the prospect of having schems I almost missed your reply,thanks for clarifying! I just wanted to have confidence that I wouldn't make the situation worse. Oh ya does the board need to be totally reconnected?

[budm]

Re: Sharp Aquos LC52SE94U hit by surge

Just the power supply board and the AC input filter board, the relay (RL7001) is turn on by the main board to by pass the inrush current limiters thermistors (TH7000/7001) otherwise the standby power supply will get the voltage through those two thermistors and it should run if there is no shorts circuit.

[Fwrothy]

Re: Sharp Aquos LC52SE94U hit by surge

So I hooked up a 60w bulb and it's like the energizer bunny!

[budm]

Re: Sharp Aquos LC52SE94U hit by surge

Yes, there is shorted circuit some where. This is with just two boards connected, right?
OK, take the resistance reading on the two outside pin of the bridge rectifier.

[Fwrothy]

Re: Sharp Aquos LC52SE94U hit by surge

Yup just the 2 boards connected. The +- pins read .3ohm

[budm]

Re: Sharp Aquos LC52SE94U hit by surge

OK, I see one protection device, Z7800 which is connected across the two outer pins of the bridge, lift up one leg of that Z7800.

[dabyd64]

Re: Sharp Aquos LC52SE94U hit by surge

Most sure blown primary transistors, maybe controller too.
In diode mode, check all the transistors that are near the bridge rectifier. I any causes "beeeep!" or near 0 ohms, then its dead.
Remember the nice bulb trick, if you replace anything always test with the bulb, because if something is still bad it will blow again breaking the new parts, or maybe more!

[Fwrothy]

Re: Sharp Aquos LC52SE94U hit by surge

OK, I see one protection device, Z7800 which is connected across the two outer pins of the bridge, lift up one leg of that Z7800.

Ok isolated Z7800 it is OL

[budm]

Re: Sharp Aquos LC52SE94U hit by surge

Still showing short on the outside pin of the bridge then? Next lift one end of the jumper J7207. We have to isolated the loads one at a time that are connected to the bridge first.

[Fwrothy]

Re: Sharp Aquos LC52SE94U hit by surge

Im following, discoed J7027 and now OL at +- on bridge.

[budm]

Re: Sharp Aquos LC52SE94U hit by surge

OK, the short is in the PFC Voltage booster circuits, you can put that jumper back in place. There are two Power MOSFETs Q7805, 7808 for the PFC circuits, so we need to find out which one (or both) is shorted out. Lift one end of the jumper J7021, that will isolate Q7808 from the circuit.
We are getting close.

[Fwrothy]

Re: Sharp Aquos LC52SE94U hit by surge

J7021 is out..

[budm]

Re: Sharp Aquos LC52SE94U hit by surge

Did you put the other jumper 7027 back in place? if not, do it, then check and see if the bridge still show as shorted or not,