TCL 43s405 power board 81-PBE045-M02 (PLE100-2A) changed out the cheap caps

[link626]

changed out the cheap HEC caps on my tv power board to a mix of nichicon chemicon and panasonic caps below.

now there's louder buzzing noise from the yellow thing in the upper left corner. (anyone know what that yellow thing does? is that the transformer?)
and the screen flickers in brightness. It's a light flicker, but noticeable.

the buzzing ebbs and flows, like cicadas buzzing.
in similar fashion, the brightness flickering ebbs and flows. the flicker might stop for a minute or two.

these are all low esr caps, and I'm wondering if that might be causing the screen flicker.
I measured capacitance of all the new caps, and they are within spec. The nichicon 82uf measured 75 though.

When I changed the caps last night, it seemed ok for hours.

After having the TV off overnight, this morning I noticed the flickering.

I dunno how to describe it, but it's as if the frequency of the caps are mismatched or something, if that's even a thing.
Anyway, it seems this set of caps together is unstable.


Do you see any potential issues with the caps I chose?

update: after a couple hours on, the flickering has subsided, but the cicada buzz still comes and goes.


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

[link626]

Re: changed out the cheap caps on my tv power board to nichicon chemicon pana. flicke

several hours later the flickering is back and it's a bit more persistent.

[SMDFlea]

Re: changed out the cheap caps on my tv power board to nichicon chemicon pana. flicke

It would be more than helpful if we knew what the make and model of the TV is,and the power board part number.

[link626]

Re: changed out the cheap caps on my tv power board to nichicon chemicon pana. flicke

It would be more than helpful if we knew what the make and model of the TV is,and the power board part number.

it's a TCL 43s405

power board 81-PBE045-M02 (PLE100-2A)


I already have a spare board. But I want to repair this board.

The new caps are all the same spec as the old ones.
So I expected the board to work flawlessly.

I read that capacitors have burn-in periods. Maybe mouser sent me old stock.


Currently day 3 of using all new caps, and the TV flickers for several minutes turning it on at the beginning of the day.

Then it stabilizes and may not flicker for several hours.
The transformer buzzes periodically, which it didn't do with the old cheapo caps.

[stj]

Re: changed out the cheap caps on my tv power board to nichicon chemicon pana. flicke

led or ccfl?

[neilc6]

Re: TCL 43s405 power board 81-PBE045-M02 (PLE100-2A) changed out the cheap caps

TCL have high rates of LED backlight failure. Turn down the backlight level and see if improves.

[link626]

Re: TCL 43s405 power board 81-PBE045-M02 (PLE100-2A) changed out the cheap caps

when it flickered, it flickered from the darkest to the brightest backlight setting.

It flickers for several minutes when I first turn on the TV in the morning.
it hasn't flickered again for the last 16 hours today.

Yesterday, it flickered for a few minutes in the morning, then was ok for most of the day, then flickered a little in the evening.


When I was using my other power board, it didn't flicker either.
So it's highly likely to be caused by one of these new japanese caps.


Something about these new caps is causing the transformer to buzz, and the backlight to flicker in the morning.

Do any of the specs seem incompatible with one another?
I was thinking you guys might know more about capacitors here.


I can't find data sheets on the old caps, but maybe the old HEC caps were not low-ESR.
Would low-esr mess with power delivery, or make it very picky about the electricity input?

[link626]

Re: TCL 43s405 power board 81-PBE045-M02 (PLE100-2A) changed out the cheap caps

the backlight didn't flicker yesterday or today so far, knock on wood.

Maybe the new caps just needed a break in period.

[Th3_uN1Qu3]

Re: TCL 43s405 power board 81-PBE045-M02 (PLE100-2A) changed out the cheap caps

There are power supplies that oscillate to various degrees when capacitors with too low ESR are used. You can either match the ESR of the originals or modify the compensation feedback circuit. Feedback circuits are finicky but a lot of times it only takes one capacitor of the right value (usually in the nF range) to stabilize the loop and prevent it from oscillating anymore.