Sharp LC-47SB57UT will not power on

[tom66]

Re: Sharp LC-47SB57UT will not power on

OK, replace the startup capacitor for 5VSB.

You may use a generic radioshack capacitor (low esr is not crucial here), though a better manufacturer would last longer.

[johnboy1313]

Re: Sharp LC-47SB57UT will not power on

OK, replace the startup capacitor for 5VSB.

You may use a generic radioshack capacitor (low esr is not crucial here), though a better manufacturer would last longer.

Here's where my ignorance comes into play. Which one is the startup cap?

[tom66]

Re: Sharp LC-47SB57UT will not power on

It's going to be one of those smaller caps on the primary side.
A picture from the bottom would enable us to determine which for sure.

[johnboy1313]

Re: Sharp LC-47SB57UT will not power on

It's going to be one of those smaller caps on the primary side.
A picture from the bottom would enable us to determine which for sure.

I may have to break it into quadrants

[tom66]

Re: Sharp LC-47SB57UT will not power on

Could you kindly highlight the locations of those caps on the bottom.
Also, near those caps is an 8-pin SMD IC, what is the part # of this?

[selldoor]

Re: Sharp LC-47SB57UT will not power on

Startup could be the one between the transformer and the heatsink just above the blue cap . There is another 47uf cap straight up from it (in your pic) just below J905 mark that one as well and say what voltage /uf they are
Hint: It is easier to follow if the fronts and backs are posted in the same orientation that is keep the top at the top on both.

[johnboy1313]

Re: Sharp LC-47SB57UT will not power on

Startup could be the onebetween the transformer and the heatsink just above the blue cap Mark that one on the back first. There is another 47uf cap straight up from it
(in your pic) just below J905 mark that one as well and say what voltage /uf they are
Hint: It is easier to follow if the fronts and backs are posted in the same orientation
that is keep the top at the top on both.

Gotcha, I've got a buddy over right now, I'll get the pics in a few minutes or so.

[johnboy1313]

Re: Sharp LC-47SB57UT will not power on

Alright, in the pic below,

Cap
1 = 470uf 16V C923 on back of board
2 = 1000uf 25V C921
3 = 220uf 25V C919
4 = 470uf 25V C918
5 = 470uf 35V C937
6 = 1000uf 35V C936
7 = 1000uf 35V CC935
8 = 100uf 50V C928
9 = 10uf 50V C927
10 = 47uf 25V C946
11 = 47uf 25V C909

[tom66]

Re: Sharp LC-47SB57UT will not power on

Great, but we need the numbers on the bottom to tell for sure which is the startup cap.

[johnboy1313]

Re: Sharp LC-47SB57UT will not power on

I'm not sure how to go about labeling these. Here's the side of the board with the connectors. The top in this pic is the same as the pic of the front.

[johnboy1313]

Re: Sharp LC-47SB57UT will not power on

Here's the other side. Not sure why I can only attach one pic at a time.

[johnboy1313]

Re: Sharp LC-47SB57UT will not power on

The number on the back is the same as the front C909, c910, etc.

[tom66]

Re: Sharp LC-47SB57UT will not power on

OK, I can see the caps clearly now, what is the pin # of that 8-pin SMD next two the two caps on top of board?

Most likely it's C926 which is the startup cap.

[johnboy1313]

Re: Sharp LC-47SB57UT will not power on

I'm getting the feeling that I'm not very good at this. I can't find a c926 anywhere and I'm not sure what 8 pin SMD even is.

[johnboy1313]

Re: Sharp LC-47SB57UT will not power on

Any chance I could get you to circle the components you're talking about?

[budm]

Re: Sharp LC-47SB57UT will not power on

I would say caps
8 = 100uf 50V C928
9 = 10uf 50V C927

As you post in post#28

You can see the connection on the bottom side of the board, the AUX winding of the transformer feeds R924 (4R7), the out out of the resistor feeds the Anode of D910, the Cathode the D910 feeds the + of C928 and the Anode of D911, the Cathode of D911 feeds the 0 Ohm resistor R905, the output of R905 feeds the+ of C927, C922, and the VCC pin of the 8-PIN SMD SMPS IC.

[tom66]

Re: Sharp LC-47SB57UT will not power on

Sorry, I misread it -- I did mean C928 as budm points out. Both might be startup caps, though I'm thinking one is the softstart cap and not critical, compared to the other. But we NEED the part # of that 8-pin SMD.

[johnboy1313]

Re: Sharp LC-47SB57UT will not power on

I really don't know what an 8 pin smd is. I can bring the board to work with me. Once I know what I'm looking for, I'll get you the number.

[selldoor]

Re: Sharp LC-47SB57UT will not power on

Ok SMD means surface mounted device 8 pins - 8 legs- 8 solder contacts
See pic - what is the part number SMD in the cream square

[johnboy1313]

Re: Sharp LC-47SB57UT will not power on

Thanks, I was looking at the other side. My eyesight isn't what it used to be. Even with my glasses and a magnifier, I can only partially make out one. The other looks like it might have a crater in it. I'm going to pull up the service manual, look at the parts list, and see if I can find it.