Re: Sharp LC70LE747 Flickering - darkening gradually to the right side
I am on to something. If I apply 12v to the PNL power supply beforehand, the unit seems to start up correctly every time. I am going to use a scope to further investigate whether this voltage reaches the level quickly enough. If I do not find immediately why the power supply fails, I will install if necessary a separate 12v power supply for PNL.
SmartSarah
Member
Last Activity: 12-02-2022, 09:35 AM
Joined: 07-29-2016
Location: Sint-Truiden, Limburg
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Re: Sharp LC70LE747 Flickering - darkening gradually to the right side
I'm puzzled why it remains good as soon as it starts good.
Once running fine, I can tap on components and parts, it stays good.
Running bad, it appears to be immune to mechanical interference like tapping or touching band wires. No impact at all.
Ruling out connection issues is too soon, but not likely either.Leave a comment:
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Re: Sharp LC70LE747 Flickering - darkening gradually to the right side
Small update on this.
It's all in the boot of the TV.
I follow this procedure nowadays.
Bad image -> pull the mains socket -> reboot (= cold restart with large red SHARP logo).
Again bad image -> repeat pulling the mains socket for a few seconds.
Good (= steady SHARP logo), so not jumping, not fading to the right -> leave it on. And than it stays fine, for weeks!!!! until next reboot.
Brightness or backlight has no influence. Last "session" it worked fine...Leave a comment:
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Re: Sharp LC70LE747 Flickering - darkening gradually to the right side
I've measured 6 x caps 470uF, all good. C7133, C7130, C7123, C7120, C7950A, C7950B.
Replaced C7123 by a new 1000uF. No difference.Leave a comment:
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Re: Sharp LC70LE747 Flickering - darkening gradually to the right side
The original T-CON has always been in place. I just swapped it shortly but since it made no difference I installed the original back.
Ok, at least I'll start measuring the 12V caps. I'm not sure if I've replacements available on the shelf. Would it hurt if I additional place caps in parallel?Leave a comment:
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Re: Sharp LC70LE747 Flickering - darkening gradually to the right side
Update - the problem returned
Inspection
- MONITOR ERR CAUSE: all 4 positions "00 0000000000000"
- BL voltages 190V, current 22mA (measured with DC current clamp)
Observations
- I've noticed extreme latency on right side during inspection (see Ghost latency 1 video)
- I made another video while toggling through LCD TEST PATTERN 2 (the other are not supported). see LCD TEST PATTERN 2
- After power off, the last image is noticeable and fading out on the...Leave a comment:
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Re: Sharp LC70LE747 Flickering - darkening gradually to the right side
Oh, I read only the page you indicated me earlier. I didn't realise what an information treasure you posted to me. I am sorry for this aberration.Leave a comment:
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Re: Sharp LC70LE747 Flickering - darkening gradually to the right side
Okay. that's the PNL 12V on the PSU board.
How did you figure out this detail?Leave a comment:
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Re: Sharp LC70LE747 Flickering - darkening gradually to the right side
The set appears to operate normally the last few days.
Reason? More in use lately, warmer room temperature, mechanical manipulations, ...
The vertical image jumping is there sometimes on top of the darkening. It's the extra factor of bad start-up indication.
I've checked the first page of the inspection. See included picture.
Lamp Error = 0
There are some monitor err causes.
1) 21 B00011422:40
2) 21 B00011399:05
3) 21 B00011251:35
4) 1A B00011239:26...Leave a comment:
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Re: Sharp LC70LE747 Flickering - darkening gradually to the right side
A few assumptions
Which module can move the image vertically?
The panel? I do not think so. Streaks, lines, dark, etc but not moving an image seems to me.
T-Con? Definitely, which is exactly what that module does. However, my replacement module does the same.
Main module? Yes it could be, if it delivers such an image T-Con cannot solve that. But how to test that without a replacement main module?
I come back to the power supply. Could it be that the quality of the delivered power...Leave a comment:
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Re: Sharp LC70LE747 Flickering - darkening gradually to the right side
The included video is during a reasonable start-up.
(Don't be mislead by the colours my camera made out of it.. The start-up logo is red on black and not white on blue as the video apparently looks like.)
The photo is one of the worst frames taken out of this video.
With reasonable start-up I mean the right side doesn't fade to much, does flickers and jumps only briefly. This is a good start and during the adjacent session it won't give a kick.
If it keeps jumping during the...Leave a comment:
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Re: Sharp LC70LE747 Flickering - darkening gradually to the right side
Bad news. The problem returned.
Backlight
- BL voltage on the 3 strings are identical, 190VDC and stable
- Looking from the back the backlight illumination is steady
I can't get my head around the following: when the TV starts without symptoms it will probably stay without problems (24h or more if you like), when it starts troublesome it won't recover, whatever I do. It's like something interferes with the boot sequence.Leave a comment:
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Re: Sharp LC70LE747 Flickering - darkening gradually to the right side
Small update
In order to measure the BL voltages I hooked up a small multi-meter with it's tilt-stand hanging on the power board.
Since then the TV worked normally.
So bad joint close to the upper part of this board? Earlier measurements with the same multi-meter setup gave me a similar impression but after a while the error returned, so I left the theory.
Now, after measuring the BL tensions, hanging the multi-meter on the board and applying some mechanical pressure on the backlight connector...Leave a comment:
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Re: Sharp LC70LE747 Flickering - darkening gradually to the right side
Therefore I've set BL to where it was initially.
Anyway to be continued.Leave a comment:
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Re: Sharp LC70LE747 Flickering - darkening gradually to the right side
Need to wait before it goes bad again. There is no problem right now.
The voltages on the 3 led strings are identical now. Depending on BL level between 130 and 191 Volt. Assumingly normal.Leave a comment:
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Re: Sharp LC70LE747 Flickering - darkening gradually to the right side
BL goes from -16 tot +16 on this set. I brought it down to -8, no effect. Even after power cycle. Did the same BL to -16 and power cycle. No result.
I noticed something weird tough. After powering off there remains an still ghost image on the troublesome side for 5 seconds.Leave a comment:
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Re: Sharp LC70LE747 Flickering - darkening gradually to the right side
The video goes bad as well, vertically misplaced.
Sometimes when I power the TV off for 10 minutes and back on, the fault disappears and it won't return during that session. A short power cycle never does the trick.
The video in attach doesn't show the vertical erratic behaviour but it happens. For this reason I think I may exclude a backlight issue....Leave a comment:
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Sharp LC70LE747 Flickering - darkening gradually to the right side
Dear,
I can not pinpoint the following problem on my Sharp TV LC70LE747E.
While the left side of the screen is not affected at all the right side of the screen gradually fades to a kind of dark. I can best describe this darkness like a totally worn out CRT display or a gamma correction totally out of range. This darkness flickers like a flame, a dark one tough.
Sometimes when I restart the TV it disappears for a while.
The problem worsened over time the last few months.
I've replaced the t-con module without success. The problem remains.
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Re: Lg - 32lh3000, 32lh5000 - dead no output
Great!
As soon as I discovered R501 to be open, I stopped diagnosing and replaced parts.
Job done! Won a lot of time thanks to this thread!Leave a comment:
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Re: Sharp LC-40LE810UN question
I had the AC-Det error (2 slow and 1 fast blinks) on a LC-40LE810E. Power at PB connector pins 1-2 and 3-4 came up for a few seconds to 12.9 V and then dropped to zero.
I didn't try anything else except lowering resistor R7019 in series of the opto led from 82K to 30k by adding a 47k in parallel. The TV set runs like a shine now.
Thanks to this board I could skip a whole lot of a hassle digging my way to a solution.
Great work!
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