Sharp LC-50LE442u will only go one once - sometimes

[mwend]

I have a Sharp LC-50LE442u that I can get to work once...

Well after reading up on suggestions here, discharging the caps, and holding the input/vol Dn buttons while plugging the unit, after about 10 sec release the buttons. The stand-by light is solid red. Pressing the remote power on button will turn the TV on and the stand-by light goes green. TV seems to work fine at this point, tested with TV Menu, HDMI and VGA/3.5mm audio.

Problem is when the TV is turned off. Press the Power button on the remote and the TV goes off and the Stand-by light goes red (as expected).
The TV will then not turn on after that, no video and no sound, but stand-by light does go to Green. At this point the power button does not seem to do anything, Stand-by light stays Green but no video and no audio

I've tested the remote power button and console push. Both have the same effect. No Video and no sound and stand-by light stays green.

All CAPs "look" OK. I've removed a few CAPs from the MainBoard for ESR testing all tested good.

I've voltage tested the power board and got some interesting results. There is no schematic and no board "labels" on what the voltage lines are. I can only use the wire color as identifiers.

** After performing the above to make the TV work,
Standy light is green, TV working
++ TV turned back on, after turning it off, Standby light is green, no video, no audio
Color TV on ( v)** TV Off (v) Turn on Again (v)++
Navy .03 .04 .04
Green .88 .02 3.3
Purple 3.3 .03 .06
Yellow 3.3 .02 3.3
Red 5.3 5.4 5.3
Red 5.3 5.4 5.3
Red 5.3 5.4 5.3
Black 0 0 0
Black 0 0 0
Orange 12.1 0 12.1
Orange 12.1 0 12.1
Orange 12.1 0 12.1
Black 0 0 0
Black 0 0 0
Black 0 0 0


Is this a Power supply board issue or a main board issue? Suggestions?

[Andrew F. Ali]

Re: Sharp LC-50LE442u will only go one once - sometimes

Seems to me that you have 5V St-By from PSU. Getting BL-ON signal, but not getting Pwr-ON signal from the Main Bd. Cold solder joints probably or e-caps ESR high on the Main Bd. Inspect the PSU for cold solder joints, too.

[dick_barton]

Re: Sharp LC-50LE442u will only go one once - sometimes

There's a thread here with a similar problem

https://www.badcaps.net/forum/showthread.php?t=46046

[Andrew F. Ali]

Re: Sharp LC-50LE442u will only go one once - sometimes

there's a thread here with a similar problem

https://www.badcaps.net/forum/showthread.php?t=46046

+1

[mwend]

Re: Sharp LC-50LE442u will only go one once - sometimes

Wow, that was fast. Thank you for the ideas. I will be removing those CAPs tonight and checking/replacing them. Hopefully I will be able to read the sides for the values and I hope I have some on hand. I'll admit, I did pass over the PSU, particularly the Primary side when I noticed I had, what seemed to be the proper voltage at secondary connector.

[mwend]

Re: Sharp LC-50LE442u will only go one once - sometimes

The 4 small CAPs seem ok. - I was hoping they were bad.

https://www.badcaps.net/forum/showthread.php?t=46046

Removed and tested the 4 small CAPs. Qty 3 - 10 uF 50v and Qty 1 - 4.7 uF 50v
All tested via ESR meter 10.3, 10.10, 10.15 , 4.77 . Similar readings with my DMM uF and Ohm readings OK. (the black stuff feels like silicon and cuts easily with a knife)

I'm up for more ideas.

[budm]

Re: Sharp LC-50LE442u will only go one once - sometimes

So what are the result of the ESR value for those caps? You only posted the Capacitance readings of the 4 caps.
"Similar readings with my DMM uF and Ohm readings OK" What do you mean by the Ohm reading OK?

[mwend]

Re: Sharp LC-50LE442u will only go one once - sometimes

Ok here are the values I measured for the 4 small CAPS
Qty 3 - 10 uF 50v and Qty 1 - 4.7 uF 50v

Cap uF, ESR(Ohm) Vloss
10.3, 1.6, 0.9%
10.1, 1.5, 1.0%
10.2, 1.5, 0.9%
4.8, 2.4, 0.5%

These are Su'scon HG caps ( double checked this HG on all)
The specs are listed herehttp://www.su-scon.com/Templates/att/HG.pdf?lng=en
but I cannot seem to find either the 4.7 or the 10 on these pages.
To me the values look to be on par with the specs on the last page, but I could be wrong on that. More eyes could certainly help.
Thoughts or this or anything else here.

For what its worth, I have a whole set of CAPs plus some extras on order from mouser.

[mwend]

Re: Sharp LC-50LE442u will only go one once - sometimes

Just a follow up on my issue here and information for all...

Solved: My power supply board (PSU) was just fine all along.
The issue was solved with a replacement main board as shown here

https://www.badcaps.net/forum/attach...4&d=1479092391

Thanks for the assistance.
..On to the next project