Replacing an RM 220uF 16V CD288H electrolytic capacitor with...  - Page 1
Forum section: electronics / beginners

author: Jay72
author_rank: Newbie
timestamp: August 18, 2025, 07:50:06 am
content: Hi All,*RM 220uF 16V CD288H electrolytic capacitor*I'm replacing five caps in an old Hikvision DVR as one of them was about to launch.One cap is a CD288H series. Ive found the specs athttps://rme.cn/ProductCenter/LeadTypeUsing the Element14 website, I found two caps - Wurth 860020373010 and Kemet ESH227M016AE3AAI'm not familiar with the intricacies of capacitor values, but this was the best I could do.Was I close?Any help appreciatedCheers,JayPS Is there somewhere that explains tan o, impedance, ripple current, mArms etc. values selection for caps? as I have a few more to get.

author: neillnz
author_rank: Contributor
timestamp: August 18, 2025, 09:55:03 am
content: You can spend a lot of time attempting to find an exact match. When you are trying to find say 10 different types you can spend hours. This is what I do:1. Look for a part with the same basic characteristic i.e. low impedance, low leakage or "general purpose" etc. This can be one of the most frustrating qualities to search for. All I do is look for a part that I think could be right and open the datasheet and look for the description. If I need a low impedance type such as that CD288H then I will look for the words "low impedance", if it's not there then I quickly close the datasheet and look at another part. I do that because the ESR spec is often not given in the search results and it takes too long looking for it in the datasheet. Once you have a same type it's then worth spending some time looking through the datasheet to see if the ripple current rating is at least as good.2. For the Voltage rating you can always go higher but of course never lower. Just bear in mind a capacitor of the same series with a higher Voltage rating will be physically larger. You may deliberately choose a higher Voltage in order to get a wider pin spacing to match the PCB.3. Check physical dimensions. Sometimes you can get away with taller or wider but not always. Pin spacing can be annoying if it's not the same.4. Life rating. You can always go higher. So a higher temp so long as the hours are the same or more. More hours is good providing it is at the same or higher temp.5. Trusted brands. You probably cannot go too wrong with anything that the likes of E14, RS and Digikey has to offer. While the likes of eBay and Aliexpress can be a great source of certain components IMHO electrolytic capacitors is not one of them!Couple of notes about the Wurth part:Datasheet for the original has the pin spacing for a 16 V 220 uF as 3.5 mm.The Wurth part has a pin spacing of 2.5 mm.Datasheet for the original has ripple current of 406 mA @ 100 kHz.The Wurth part is 215 mA @ 120 Hz. So less current but more concerning it is specified at a much lower frequency which suggests this is not a low ESR / low impedance part.The Kemet part looks to be a general purpose type.Lastly, this is far from a comprehensive guide, have you checked out:https://www.badcaps.net/

author: PGPG
author_rank: Frequent Contributor
timestamp: August 18, 2025, 11:26:22 am
content: The first question is: Do you need low ESR capacitor or not?If it works in DCDC converter it have to be low ESR if it works in standard 50Hz (or 60Hz) rectifier it need not to be low ESR.Capacitors having their ripple current specified at 100kHz are low ESR and those having it specified at 120Hz are not.It would be good to find capacitor with ripple current equal or higher than one that you replace, but have in mind that capacitor used could have higher current than minimum needed just because they used that capacitor serie.

author: Jay72
author_rank: Newbie
timestamp: August 18, 2025, 01:14:54 pm
content: Quote from: neillnz on August 18, 2025, 09:55:03 amThank you.Quote from: neillnz on August 18, 2025, 09:55:03 amYes, it does (typo on the datasheet?). Although the cap on the board has 2.5mm pin spacing and is 6.3 x 11mm - I should've added the dimensions to the post.Quote from: neillnz on August 18, 2025, 09:55:03 amThat's where I'm clueless - not knowing good or bad current values.Quote from: neillnz on August 18, 2025, 09:55:03 amSnow-blind from too much searching?Quote from: neillnz on August 18, 2025, 09:55:03 amJust had a quick look at that site, looks great.Thanks for your reply neillnz

author: Jay72
author_rank: Newbie
timestamp: August 18, 2025, 01:30:10 pm
content: Quote from: PGPG on August 18, 2025, 11:26:22 amI don't know.Quote from: PGPG on August 18, 2025, 11:26:22 amThe DVR has a 12v input.Quote from: PGPG on August 18, 2025, 11:26:22 amThe datasheet seems to have both and only shows dissipation factor - which I'm not sure of.Quote from: PGPG on August 18, 2025, 11:26:22 amI'm still to discover ripple current relevance.Thanks PGPG. Swapping out caps is a little more involved than I thought.