Sharp LC-40LE820M No power

[bappies7]

Hi,


Anybody of u out here have the schematics of the power board from delta electronics.

Sharp part no : RUNTKA687WJQZ

The LED TV have no standby light at all, completely dead.

Check on the power board,found the 2 x main 5A fuse still not blown yet (Short).

After much fault finding, found a short at IC7003 (MIC5209-5.0YS) between pin 1 & 2. But after removing the IC, the short is still there.


I'm struck without the schematics.

Any kind soul have the same problem as me before?


Thank you.

[bappies7]

Re: Sharp LC-40LE820M No power

Anybody ????

[Caleb]

Re: Sharp LC-40LE820M No power

The service manual is HERE, didnt have time to look through it though so Im not sure if it will have schematics

Some good pictures front and back of the power board would be very helpful for any of the techs on here to help you work through your power supply.

[budm]

Re: Sharp LC-40LE820M No power

Good pictures will help. Did you have power surge? Was this TV worked on by some one else before? just need some info to find out when the problem started.

[bappies7]

Re: Sharp LC-40LE820M No power

Attached are the photos of the powerboard.

[budm]

Re: Sharp LC-40LE820M No power

Can I see the picture of the pads where IC 7003 is connected to, trying to figure out if cap c7928 is connected to one of the pin, that cap is MLCC type which will failed as shorted circuit.

[budm]

Re: Sharp LC-40LE820M No power

Here is the spec sheet of IC7003, as you can see, there is small filter cap on input pin 1. Pin 2 i Ground, pin 3 is the output.
BTW, the resistance reading is <1 Ohm?
BTW, how about the RED ROUND fuse on the left side of the board? OK?
Never mind, that is not fuse, it is capacitor, hard to tell when pictures are not in focus.

[budm]

Re: Sharp LC-40LE820M No power

Can I also getting better focused and higher res pictures of the top and bottom side of the board, it is good enough for me to trace out all those traces on the board to figure out the connections.
The whole pictures of the board and then may be in sections will be great also.

[budm]

Re: Sharp LC-40LE820M No power

See the redline, it looks like the fusible resistor pads have bad solder, that fusible resistor feed the b+ from those two main filter caps to the STBY power supply section which is generated by that transformer by the barcode sticker.

[bappies7]

Re: Sharp LC-40LE820M No power

Can I see the picture of the pads where IC 7003 is connected to, trying to figure out if cap c7928 is connected to one of the pin, that cap is MLCC type which will failed as shorted circuit.

I have removed and check c7928 it is working fine.

[bappies7]

Re: Sharp LC-40LE820M No power

Can I also getting better focused and higher res pictures of the top and bottom side of the board, it is good enough for me to trace out all those traces on the board to figure out the connections.
The whole pictures of the board and then may be in sections will be great also.

Ok will upload in a while.

Thanks..

[bappies7]

Re: Sharp LC-40LE820M No power

Here is the spec sheet of IC7003, as you can see, there is small filter cap on input pin 1. Pin 2 i Ground, pin 3 is the output.
BTW, the resistance reading is <1 Ohm?
BTW, how about the RED ROUND fuse on the left side of the board? OK?
Never mind, that is not fuse, it is capacitor, hard to tell when pictures are not in focus.

Managed to get the power supply schematics for another model RUNTKA686WJQZ. After looking through, it looks some how similar.

I have removed IC7003, C7928, C7961A, D7907, R7939. And the short still exists between IN and GND of IC7003.

[bappies7]

Re: Sharp LC-40LE820M No power

Attached are the Hi Res photos of the powerboard.

[bappies7]

Re: Sharp LC-40LE820M No power

anybody knows.....

[Caleb]

Re: Sharp LC-40LE820M No power

Usually when I cant find the source of a short I tie a current limited power source to the circuit and see what gets hot first.
5v source----10ohm 5w resistor---to positive, ground to negative freeze spray the board and see what melt the fastest.

[anbcunningham]

Re: Sharp LC-40LE820M No power

bappies7 - Did you mange to get this tv working yet? I have an LC-60LE820UN that I think is having a power issue as well. When I plug the TV in, I get nothing. I'm thinking its a short on the power board, but can't seem to track it down. On your set, do you have any front panel indicators that tell you the set has power? One more question, How did you test IC7003 to determine there was a ground? Please forgive me for the novice question, I'm still learning. This is a nice (big) tv that would build my confidence if I can get it working. I bought it off craigslist for $20 in the hopes I can get it running again. Any information would be greatly appreciated!

BTW - I'm try to get away from just replacing boards. I want to be able to repair board level issues! It makes the task so much more enjoyable! Last night I fixed a Panasonic Plasma by replacing components on the SS board (and it worked - YEAH!!) Spent $19 for a 50" tv that was going to the dump! Now someone can use it in there house for a couple more years and keep it out of the landfill.