long electrolytic capacitors - Page 1
Forum section: electronics / repair

author: lamoule74
author_rank: Contributor
timestamp: June 02, 2022, 01:49:22 pm
content: Hey electronic guys,I dismantled a large TV wich seems to have deffectuous capacitors on the power supply board...I think it won't be bad if change all of them...But I have some doubts, the capacitors got a lonnnnng design like attached (see picture).Does the size matters ? I suppose not, because it is quite difficult to find all these references with this "cigarette" size!I've got this list:560 µF 35 V (×2)220 µF 16 V (×2)47 µF 450 V (×2)47 µF 200 V (×4)1500 µF 35 V (×1)Please let me know.Cheers.

author: SeanB
author_rank: Super Contributor
timestamp: June 02, 2022, 02:22:34 pm
content: Length normally used because the wider ones do not fit the limited area on the board. If you have wider low ESR 105C capacitors which will still fit there no problem to use them, generally the longer ones are used for tighter packing, but the manufacturer could be using them simply because they have them in stock and the board layout can fit wider ones, as often you see the screen printed layout has a few different diameters printed as concentric circles, the actual capacitor fitted depends what is on the machine that day, or what they have in stock in that value and voltage. Otherwise the ESR is the same, the voltage the same or slightly higher, and capacitance the same or slightly higher, and they fit the pitch of the leads no problem to use other diameter cans.

author: lamoule74
author_rank: Contributor
timestamp: June 02, 2022, 03:14:00 pm
content: hello @SeanB,sound logical...Thank you !

author: strawberry
author_rank: Super Contributor
timestamp: June 02, 2022, 03:37:58 pm
content: lifetime is differentfor some reason(high board temperature) they didnt use many low height capacitorsreduce back light current by ~20-30% to get more lifespan and some heatsink for CPU. otherwise your effort might be worthless

author: nightfire
author_rank: Frequent Contributor
timestamp: June 02, 2022, 04:55:06 pm
content: The long form helps a bit with distributing heat for cooling purposes.Otherwise the most important things also have been mentioned already:Basically, values, ESR, and temp rating should be the same, for temp and voltage it does not hurt to go one step higher.Also it does not hurt to put in reputable brands, especially those that are known to be safe against ripple voltage...

author: lamoule74
author_rank: Contributor
timestamp: June 02, 2022, 06:45:45 pm
content: I often use panasonic...thank you all

author: wraper
author_rank: Unknown
timestamp: June 02, 2022, 06:49:02 pm
content: If you use usual capacitors, you most likely won't be able to assemble TV back because PCB will become thicker. They lie flat on the board, often within cutouts to lower PCB profile. Such PSU boards also use low profile transformers.

author: free_electron
author_rank: Super Contributor
timestamp: June 02, 2022, 06:52:22 pm
content: these tall capacitors are typically for pulsed currents. The wider and shorter foil means the electrons do not need to travel that far to the end of the plate. ( take a long piece of paper and roll it up , versus a wide , shorter piece of paper )typically these things are very low ESR and have high ripple current ability.

author: wraper
author_rank: Unknown
timestamp: June 02, 2022, 06:56:03 pm
content: Also I somewhat doubt bad capacitor claim, especially if none of them are bulging. It's not year 2010 when this was the most common failure.