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Old 09-01-2021, 11:02 AM   #1
link626
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Default damn. I'm disappointed these high quality caps made my power supply worse

I thought my tv power supply was stable. It's been stable for a few weeks since I swapped in nichicon, united cc, panasonic caps to replace the cheap china caps.

But today it caused my tv to have a flickering spasm again.

what a letdown.

I swapped back my backup power board which has cheap china caps, and the tv backlight stopped flickering.


Sometimes these high quality caps just don't make things better.
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Old 09-01-2021, 11:38 AM   #2
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Default Re: damn. I'm disappointed these high quality caps made my power supply worse

Quote:
Originally Posted by link626 View Post
I thought my tv power supply was stable. It's been stable for a few weeks since I swapped in nichicon, united cc, panasonic caps to replace the cheap china caps.

But today it caused my tv to have a flickering spasm again.

what a letdown.

I swapped back my backup power board which has cheap china caps, and the tv backlight stopped flickering.


Sometimes these high quality caps just don't make things better.
Three items:
  1. Capacitors aren't the only thing that fail in PSUs. Trasistors and MOSFETs like to blow up as well!
  2. Did you get legit caps? If you got them on eBay or alibaba/aliexpress, then they very well may be fakes.
  3. Were they the right caps? The ESR has to be close, the voltage rating high enough (more is fine, less isn't unless you're sure the rail won't go too high), and the temp. rating high enough (in a TV, I would go for 105C or higher, 85C will burn/blow from the heat!). Just matching size and capacitance isn't enough.

This all assumes the recap went well and the soldering was good... if the joints failed or something got overheated from a really rough install, all bets are off.
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Old 09-01-2021, 08:34 PM   #3
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Default Re: damn. I'm disappointed these high quality caps made my power supply worse

soldering was good.

legit caps bought from mouser.

all 105C rated, exact same capac and voltage specs as the original china caps.

most of these new caps are low ESR, but I'm not sure if the original china caps were low ESR. I'm guessing the chinas were general purpose.


I'm gonna swap back the cheap china caps and see if the flickering goes away.
With the china caps, the original board did not cause backlight flicker.
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Old 09-03-2021, 06:56 AM   #4
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Default Re: damn. I'm disappointed these high quality caps made my power supply worse

Did you take ripple into effect, not just ESR?

Also, PSU caps don't need to be low ESR. Low ESR tends to be used for things like motherboard PSU's. If your ESR is too low, that can cause problems. Switching PSU's won't operate right without the esr and especially ripple being within a certain amount as the original caps (though the temp being higher is always better)
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Old 09-03-2021, 04:55 PM   #5
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Default Re: damn. I'm disappointed these high quality caps made my power supply worse

Quote:
Originally Posted by link626 View Post
I thought my tv power supply was stable. It's been stable for a few weeks since I swapped in nichicon, united cc, panasonic caps to replace the cheap china caps.

But today it caused my tv to have a flickering spasm again.

what a letdown.

I swapped back my backup power board which has cheap china caps, and the tv backlight stopped flickering.


Sometimes these high quality caps just don't make things better.
Can you please tell us what series of capacitors did you use
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9 PC LCD Monitor
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10 Battery Charger Switching Power Supply for Power Tool
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25 Servo Drives 220/460 3 Phase
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15 Computer Power Supply
1 HP Printer Supply & Control Board * lighting finished it *


These two repairs where found with a ESR meter...> Temp at 50*F then at 90*F the ESR reading more than 10%

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All of these had CAPs POOF
All of the mosfet that are taken out by bad caps
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Old 09-06-2021, 06:41 PM   #6
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Default Re: damn. I'm disappointed these high quality caps made my power supply worse

Quote:
Originally Posted by Uranium-235 View Post
Did you take ripple into effect, not just ESR?

Also, PSU caps don't need to be low ESR. Low ESR tends to be used for things like motherboard PSU's. If your ESR is too low, that can cause problems. Switching PSU's won't operate right without the esr and especially ripple being within a certain amount as the original caps (though the temp being higher is always better)
Quote:
Originally Posted by sam_sam_sam View Post
Can you please tell us what series of capacitors did you use


how do I account for ripple?

I didn't intentionally buy low ESR caps. They were just the only ones available of the same dimensions as the old caps.

These were the caps I bought...



Mfr. #: EKYA101ELL470MJC5S
UCC 100V 47uF 480mA ripple

Mfr. #: UHE1E681MHD6TO
nichicon 680uF 25 Volts 1400mA ripple

Mfr. #: EEU-FR1H100B
panasonic 50VDC 10uF 250mA ripple

Mfr. #: UPZ2W820MNY9
nichicon 450V 82uF 730mArms 730mA ripple

Mfr. #: URY2C330MHD1TO
nichicon 33uF 160V 130mA ripple

Mfr. #: EEU-FC1H101B
panasonic 100uF 50volts AEC-Q200 615mA ripple
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File Type: jpg IMG_20210906_174515.jpg (786.2 KB, 24 views)

Last edited by link626; 09-06-2021 at 06:50 PM..
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Old 09-07-2021, 12:27 AM   #7
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Default Re: damn. I'm disappointed these high quality caps made my power supply worse

There are generalized caps used for power supplies, as well as some high ripple ones used too. Find who made your old caps, look at the series, and look at the usage. If they're "general", try to find decent quality general usage ones that have a close matching ripple. You will generally not see low ESR type caps used in PSU's except on the PFC controller circuit
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Old 09-07-2021, 01:47 PM   #8
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Default Re: damn. I'm disappointed these high quality caps made my power supply worse

The last thing to look at is size, when you can match the other 4 specs then look at size.
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Old 09-07-2021, 04:28 PM   #9
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Default Re: damn. I'm disappointed these high quality caps made my power supply worse

Quote:
Originally Posted by Uranium-235 View Post
There are generalized caps used for power supplies, as well as some high ripple ones used too. Find who made your old caps, look at the series, and look at the usage. If they're "general", try to find decent quality general usage ones that have a close matching ripple. You will generally not see low ESR type caps used in PSU's except on the PFC controller circuit

That's the problem

the old HEC brand china caps have no spec sheets on google.
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Old 09-07-2021, 04:29 PM   #10
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Default Re: damn. I'm disappointed these high quality caps made my power supply worse

Quote:
Originally Posted by brethin View Post
The last thing to look at is size, when you can match the other 4 specs then look at size.

This power board has low clearance, and all caps must be under 16mm in height, or else the back cover wouldn't fit.

there weren't a lot of choices.
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Old 09-08-2021, 04:23 AM   #11
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Default Re: damn. I'm disappointed these high quality caps made my power supply worse

Quote:
Originally Posted by link626 View Post
But today it caused my tv to have a flickering spasm again.

what a letdown.

I swapped back my backup power board which has cheap china caps, and the tv backlight stopped flickering.
Backlight flicker isn't regularly caused by bad capacitors... and much less if they weren't bad to begin with.

You need to do more troubleshooting on your end. Shottgunning parts (swapping without having identified which components are failed) is not the best way to troubleshoot (though in some situations, it does make sense.)

As for the discussion regarding the replacement caps not having "proper" ripple current specs or generally made for PSUs - that's irrelevant to the problem here. If the original HEC caps were truly failed and the cause of the problem, then any GP (general purpose) cap replacement would have at least gotten the set to work fine, and certainly for more than just a few weeks.

So again, I highly suspect the issue with the backlight flicker here isn't related to the caps at all and O/P should check the backlight system of the TV. If it's an LED-backlit TV, check for open/shorted or just plain-intermittend LEDs in the backlights (well, that's certainly easier being said than done. ) A bench PSU with high enough voltage and variable current output would be the best way to check the strips. The LED driver circuit could also have components that are bad or drifted out of tolerance. If it's a CCFL backlit TV, one or more of the CCFLs may just be approaching its EOL. Or it could be that there is a bad solder joint somewhere. A few good pictures of the bottom side of the PCBs may help spot those.

Other than that, good job with the recap. The replacement caps you picked are actually suitable for PSU use.
Now, if the TV runs really hot, more special caps may be needed... but that's unlikely to be the case.

Last edited by momaka; 09-08-2021 at 04:29 AM..
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Old 09-08-2021, 02:21 PM   #12
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Default Re: damn. I'm disappointed these high quality caps made my power supply worse

Quote:
Originally Posted by momaka View Post
Backlight flicker isn't regularly caused by bad capacitors... and much less if they weren't bad to begin with.

You need to do more troubleshooting on your end. Shottgunning parts (swapping without having identified which components are failed) is not the best way to troubleshoot (though in some situations, it does make sense.)

As for the discussion regarding the replacement caps not having "proper" ripple current specs or generally made for PSUs - that's irrelevant to the problem here. If the original HEC caps were truly failed and the cause of the problem, then any GP (general purpose) cap replacement would have at least gotten the set to work fine, and certainly for more than just a few weeks.

So again, I highly suspect the issue with the backlight flicker here isn't related to the caps at all and O/P should check the backlight system of the TV. If it's an LED-backlit TV, check for open/shorted or just plain-intermittend LEDs in the backlights (well, that's certainly easier being said than done. ) A bench PSU with high enough voltage and variable current output would be the best way to check the strips. The LED driver circuit could also have components that are bad or drifted out of tolerance. If it's a CCFL backlit TV, one or more of the CCFLs may just be approaching its EOL. Or it could be that there is a bad solder joint somewhere. A few good pictures of the bottom side of the PCBs may help spot those.

Other than that, good job with the recap. The replacement caps you picked are actually suitable for PSU use.
Now, if the TV runs really hot, more special caps may be needed... but that's unlikely to be the case.


I have another power board with original HEC caps that I swapped in
and the backlight does not flicker at all right now.

so my conclusion is the backlight is fine.


Even the original powerboard would not flicker like this before I replaced the caps.

That's why I'm thinking something is wrong with the combo of new nichicon/chemicon/pana caps I put in.

The new caps also caused the transformer to make buzzing noises it didn't used to have
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Old 09-11-2021, 06:45 PM   #13
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Default Re: damn. I'm disappointed these high quality caps made my power supply worse

Quote:
Originally Posted by link626 View Post
I have another power board with original HEC caps that I swapped in
and the backlight does not flicker at all right now.

so my conclusion is the backlight is fine.
I still wouldn't conclude that.

Consider this: every time you take out / swap the power supply, you're also moving around connectors and parts inside the TV. A bad solder joint or connector could easily cause this kind of intermittent problem to make one board seem good and the other one not.

I'd give it more time and use before concluding that. Also, consider the ambient temperatures in the room too. Now that Fall is coming and we get cooler weather, this too can affect any intermittent joints and connections.

Quote:
Originally Posted by link626 View Post
Even the original powerboard would not flicker like this before I replaced the caps.

That's why I'm thinking something is wrong with the combo of new nichicon/chemicon/pana caps I put in.

The new caps also caused the transformer to make buzzing noises it didn't used to have
Re-check your soldering then, along with the entire rest of the board that you worked on for possible solder joint damage from handling on other parts.

The cap series you used are overall quite normal for PSU use. Probably only the 100V 47 uF UCC KYA and the 33 uF 160V Nichicon RY may not be the best choices when it comes to low ESR caps, as those two aren't exactly low-ESR. But Panasonic FC and Nichicon HE are fine for PSU use. FR, FS, and FM I would say it depends on the PSU - most will work fine with them, but I have found there are PSUs that would become louder / whine after recapping with FR/FS/FM. So I don't usually recommend those, though they should work in pretty much all cases (and I personally have not seen a PSU that hasn't.)

As for Nichicon PZ - that's not low-ESR... but that's your input bulk cap, and it's standard for those not to be low-ESR. In fact, PZ is just a smaller version of the PT series, and the PT series is what the PlayStation 3 uses in their power supplies on the primary side (i.e. same application as in your PSU.)

So if you do suspect any problem with the caps, you can test your theory by swapping caps between PSUs and seeing if the problem follows. If not, then it's not the caps. On that note, if you do decide to swap caps around, try starting with the Panasonic FR first, then the UCC KYA and Nichicon RY.
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