I need to change a capacitor, but can't find the same one - Page 1
Forum section: electronics / beginners

author: GLeader
author_rank: Newbie
timestamp: January 31, 2021, 03:11:46 pm
content: Hi,I need to change some capacitors in my monitor (in its integrated PSU), but i can't find the same ones.for exemple i need a 1000 uF @ 10v . i only found 1000 uF @ 16vso my question is what is more important the "uF" or "v" ?for exemple for a 1000 uF @ 10v can i change it with 1500 uF @ 10v or 1000 uF @ 16v or maybe something els ?thanks.

author: Yansi
author_rank: Super Contributor
timestamp: January 31, 2021, 03:14:41 pm
content: There are way more properties of a cap, other than the maximum working voltage and rated capacitance. Depending on an application, they may become pretty important too.So, what cap exactly and where are you trying to replace and why?

author: tunk
author_rank: Super Contributor
timestamp: January 31, 2021, 03:19:08 pm
content: If possible keep the capacitance the same, andthe voltage rating should be the same or higher.So 1000uF/16V should be fine (assuming the ESRvalues are similar).Edit: A photo of it may help.

author: Dennis Frie
author_rank: Contributor
timestamp: January 31, 2021, 03:24:45 pm
content: The voltage-rating is the maximum voltage allowed. So a 16V 1000uF capacitor will work fine for anything below 16V. Generally speaking, the only downside of using a higher voltage-rating capacitor is size and cost.Note, that if used in a power-supply, you might want to be aware of ripple rating and temperature rating too. If you are just replacing a single cap, it might be easier to just pick a high temperature version with high ripple rating

author: Terry Bites
author_rank: Super Contributor
timestamp: January 31, 2021, 04:28:05 pm
content: PSU brand?Photo?

author: wraper
author_rank: Unknown
timestamp: January 31, 2021, 04:51:01 pm
content: Monitor almost certainly has low esr capacitors.

author: GLeader
author_rank: Newbie
timestamp: January 31, 2021, 05:13:26 pm
content: Quote from: Yansi on January 31, 2021, 03:14:41 pmi guss yeah, do you have any video explaining this stuff for a noobie ?im trying to replace my monitor's caps (it's an old one, so last time i did replace them and it worked fine for like a year or two)the monitor is "samsung SyncMaster 205 BW" and the caps are for the PSU inside the monitor. (sry i can't open it at the moment (to take pictures) i'm using it now)for the why. the monitor sometimes doesn't turn ON, or it turn ON with a black screen. i have to unblug it (from the wall) and blug it again multiple times to make it work.Quote from: tunk on January 31, 2021, 03:19:08 pmBlack one is the old (not working), the brown one is the new.sorry for the pictures quality the phone flash was a pain.Quote from: Dennis Frie on January 31, 2021, 03:24:45 pmthe problem is that where i live the store doesn't have the same caps as i needi will try to find the same, but if the one i got could work then cool.Quote from: Terry Bites on January 31, 2021, 04:28:05 pmbrand : i have no idea (can't open the monitor now), but i have these old pictures tho i dont think they will help you (and they are bad).PS: if you are wondering how do i use the monitor and at the same time i have the old capacitor out, its because i changed it some time ago and i kept it in case i need to find a replacment

author: Per Hansson
author_rank: Unknown
timestamp: January 31, 2021, 05:33:35 pm
content: You can find some lengthy threads on the Badcaps forum about this monitor including suggested replacement capacitor lists, it is very common to fail.Maybe it would be easier for you to buy a kit? It is not something I normally condone (Mouser, Digikey or Elfa is much better). But in your case maybe it is easier?Otherwise if you buy not good enough caps locally they will just fail in a few months again...https://www.ebay.com/itm/Repair-Kit-Samsung-SyncMaster-205BW-LCD-Monitor-Caps/330524286056TheSamwha RDcapacitor you showed is not LOW ESR / low impedance, it is a general purpose cap and it will fail very quickly if you install it in place of aCapxon KF.The reason the Capxon fails is because they are utter garbage too, but at least it is LOW ESR so it lats for a while (usually till the warranty runs out on the monitor).

author: GLeader
author_rank: Newbie
timestamp: January 31, 2021, 05:37:52 pm
content: Quote from: Per Hansson on January 31, 2021, 05:33:35 pmok thanks for the infosand no i can't get a kit, because i would like to change this monitor anyway, i just need it to run a bit more time

author: wraper
author_rank: Unknown
timestamp: January 31, 2021, 05:43:48 pm
content: Quote from: Per Hansson on January 31, 2021, 05:33:35 pmEven if buying on ebay, I would buy them separately. Not a stupid kit of 5 cheap capacitors for $9. Even if they are notch caps like Panasonic, it's not worth more than 2-3 bucks.

author: Per Hansson
author_rank: Unknown
timestamp: January 31, 2021, 08:13:22 pm
content: Oh absolutely, this was more about paying someone else to do the job for you, i.e. to find the appropriate caps for a novice it might be worth the expense plus the included extras.According to some posts on Badcaps and guesses based on the pictures in this thread this would be good replacements, Digikey part numbers:4x 493-1558-ND1x 493-1583-ND1x P13478-NDThe small startup cap is not even included in the eBay kit...That said GLeader if you just want it to live for a little while (few weeks/months) maybe GP (general purpose) caps will work.But you first need to match the voltage, the originals are 25v and your new one is 16v.Maybe you have some old power supplies you can scavenge old used caps from, anything would be better than GP capacitors.Using GP caps in place of LOW ESR caps could also result in other failures like switching components overheating.

author: GLeader
author_rank: Newbie
timestamp: February 01, 2021, 01:09:40 am
content: Quote from: Per Hansson on January 31, 2021, 08:13:22 pmgood call for the old PSU, i will see if i can get some caps from them.is there a way to check if the caps are good before i put them in the monitor ? (i only have a basic multimeter)

author: RoGeorge
author_rank: Super Contributor
timestamp: February 01, 2021, 01:19:24 am
content: Quote from: GLeader on January 31, 2021, 03:11:46 pmThat will work. Using a slightly higher voltage than the original is OK. Never use lower voltage than original, it may explode.Respect the polarity when replacing the old capacitors with the new ones, and it will work just fine.

author: Per Hansson
author_rank: Unknown
timestamp: February 01, 2021, 07:39:00 pm
content: Quote from: GLeader on February 01, 2021, 01:09:40 amYou can buy the "transistor tester" on eBay, it has ahuge thread here on eevblog.But with no equipment it is also possible with two simple tests: first is to charge the capacitor to its rated voltage and leave it to the next day:If it still shows almost the same voltage as the previous day it has very low leakage.Second is to charge the capacitor and short it with something metal you are not careful about.If you get a nice spark it means the capacitor has quite low ESR, if you don't get sparks the capacitor is end of life.Extra tip: it is better to charge the capacitor through a 1K resistor,Especially for example if it is a 25v capacitor but it has been installed in a 10v circuit its whole life:If you charge it directly to 25v without a resistor it can fail.