Sharp LC-52LE830U Lightning Strike No Standby

[johnboy1313]

A friend's dad stopped by and dropped this off for me. No LED on the front when plugged in. 166V across the big cap. Nothing else. No voltages present at any of the pins on the connector to the main board. This set was the victim of a lightning strike. Looks like the PSU is fried, I suspect the main board is probably no good too.

Power supply pictures from ShopJimmy. I can get closeups of specific areas if needed.
http://www.shopjimmy.com/sharp-runtk...t-inverter.htm

I've attached the useful part of the SM. Everything else is teardown, setup, main board schematics, or parts lists.

[johnboy1313]

Re: Sharp LC-52LE830U Lightning Strike No Standby

Bump

[tom66]

Re: Sharp LC-52LE830U Lightning Strike No Standby

Check voltage across any small electrolytic caps on the primary, one is probably a start up cap.

[ben7]

Re: Sharp LC-52LE830U Lightning Strike No Standby

^ I second that.

By the sound of it, either the standy supply is toast, the mainboard, or both have been toasted.

[johnboy1313]

Re: Sharp LC-52LE830U Lightning Strike No Standby

I checked voltages across every electrolytic cap on the board. The only ones with any voltage are the 3 long 450V caps that show 166V across each one.

[ben7]

Re: Sharp LC-52LE830U Lightning Strike No Standby

I checked voltages across every electrolytic cap on the board. The only ones with any voltage are the 3 long 450V caps that show 166V across each one.

There is a 7-pin DIP chip near that "Delta" logo. (Delta is a PSU making company)
There are two small electrolytic capacitors near the chip. With the power supply unplugged, can you please measure the resistance across these two capacitors?

Also some more up-close pictures of that area would be nice. (Front and back of the board, mind you!)

[johnboy1313]

Re: Sharp LC-52LE830U Lightning Strike No Standby

The brown 63V, 47uf cap above the A of the Delta logo starts at 0 and immediately jumps until it steadies out around 150kΩ. The small black 100V, 1uf cap above the triangle shaped Delta symbol starts at 0 and quickly jumps until it steadies out around 56Ω. I'll try to get better pics this afternoon.

[tom66]

Re: Sharp LC-52LE830U Lightning Strike No Standby

I'd look at the 100V/1uF cap -- trace the IC connected it.

[ben7]

Re: Sharp LC-52LE830U Lightning Strike No Standby

The brown 63V, 47uf cap above the A of the Delta logo starts at 0 and immediately jumps until it steadies out around 150kΩ. The small black 100V, 1uf cap above the triangle shaped Delta symbol starts at 0 and quickly jumps until it steadies out around 56Ω. I'll try to get better pics this afternoon.

Try removing the 7-pin chip, and see if the resistance across the 1uF capacitor is much higher.

Will need some good pics of that area of the board, front and back.

[ben7]

Re: Sharp LC-52LE830U Lightning Strike No Standby

I'd look at the 100V/1uF cap -- trace the IC connected it.

The issue is probably with the small 7-pin chip, since it is highly likely that is controlling the standby power supply. OP stated that the 5v standby isn't even present.

[tom66]

Re: Sharp LC-52LE830U Lightning Strike No Standby

That'd be my guess too. It's relatively common for the internal Vcc path to short, especially if the in-built MOSFET breaks down transiently (putting 400V on the Vcc.)

[johnboy1313]

Re: Sharp LC-52LE830U Lightning Strike No Standby

The IC is labeled...

1129
TNY264PN
94599E

I'm not really sure how to test it. I think this is the datasheet.

https://cdn.badcaps-static.com/pdfs/...bb528125a8.pdf

Here are some pics. I hope they help. The first pic is the back of the IC.

[johnboy1313]

Re: Sharp LC-52LE830U Lightning Strike No Standby

Here's the other side of the board. Again, the first pic is the area in question.

[tom66]

Re: Sharp LC-52LE830U Lightning Strike No Standby

Check the voltage on drain, the exposed pin 8, negative lead on big 400V cap negative.
Check the voltage on BP, the first pin on the device. Should be 5.8V in operation.

[johnboy1313]

Re: Sharp LC-52LE830U Lightning Strike No Standby

Pin 8 = 0V
Pin 1 = 166V

Both measured with the black lead on the big cap.

[tom66]

Re: Sharp LC-52LE830U Lightning Strike No Standby

My bad. Please check pin 5 which should be drain, or around 160V.
Looks like the IC is bad though with an internal short from drain to Vcc.

[ben7]

Re: Sharp LC-52LE830U Lightning Strike No Standby

My bad. Please check pin 5 which should be drain, or around 160V.
Looks like the IC is bad though with an internal short from drain to Vcc.

Yep that is exactly what I was thinking too

[johnboy1313]

Re: Sharp LC-52LE830U Lightning Strike No Standby

166V at pin 5 and pin 6 too if that matters.

[tom66]

Re: Sharp LC-52LE830U Lightning Strike No Standby

Pin 6? That is a missing pin? Do you mean pin 7 (which is the 6th counting clockwise)?

[mr2013e]

Re: Sharp LC-52LE830U Lightning Strike No Standby

which smps pwm controller talking about?
TNY264PN
if ic is bad, check the mosfet.it could be short.