Primary capacitors - general question

Collapse
X
Collapse
 
  • Page of 1
  • Time
  • Show
Clear All
new posts
Previous template Next
  • Majestyk
    Senior Member
    • Nov 2013
    • 96
    • Germany
    #1

    Primary capacitors - general question

    Hello everybody,

    accordig to the datasheets capacitors with for example 470uF, a voltage rating of 400V and 85°C are typically able to stand a ripple current of about 3.5A
    A similar capacitor for 105°C can only stand a ripple of about 2.5A.
    It seems to be impossible to produce a capacitor that would have both a high temperature rating and high ripple capabilities at the same time.

    Of course everybody would prefer the 105° cap as a replacement.
    My question is: Could there be a need for a rating of 3.5A ripple in ATX PSUs after the bridge-rectifier and could this be the reason why many PSUs are equipped with 85° primary filtercaps?
    Tags: None
    • SM-Piyes90
      Senior Member
      • Feb 2014
      • 120
      • Morocco
      #2
      Re: Primary capacitors - general question

      Don't know if this sounds correct but i guess when the temp goes up , current decreases with . So it impossible to have both parameters high

        Comment

        Previous template Next

        Related Topics

        Collapse
        • chth96
          Is it no harm to replace with capacitor without ripple current rating?
          by chth96
          When I tried to repair LG 29 inch CRT TV, I found that the ESR value of samyoung SMS capacitor(160v 2.2uf), which is very close to D1879 transistor, is 6 ohm.


          Judging from above ESR Meter Table,I think It is necessary to replace this sms capacitor.So I visited local electronics shop,and I purchased 160v 2.2uf rubycon YK capacitor.
          But when I browse through rubycon YK datasheet,I found that there is no ripple current rating for 160v 2.2uf specification. But On the contrary, I found 39 mA ripple current rating for 160v 2.2uf SMS capacitor.
          Rubycon YK DataSheet (b...
          04-19-2024, 05:19 AM
        • quickname
          Cyberpower 1500AVR UPS repair
          by quickname
          I'd like to start out by thanking this forum for providing the info to be able to repair my 15 year old CP1500AVRLCD UPS. Here is all the info I gathered during my trouble-shooting and re-capping.

          Like clockwork, I've had to replace the SLA batteries every 4 years. It was about that time and the UPS was acting like it needed new batteries... randomly shutting off with AC present, not being able to charge fully, and poor runtime when AC was removed. So, I replaced the batteries but noticed that it was not charging properly.

          I decided to verify that the batteries were...
          11-12-2023, 09:57 AM
        • Agent24
          Dick Smith Q-1760 linear power supply filter capacitor question
          by Agent24
          I have acquired a used Dick Smith Q-1760 power supply - although the OEM is Manson Industrial
          It has at least one problem.

          The voltage control potentiometer VR2, 50K is faulty - going high resistance / open circuit in the CCW end and leading to the output voltage jumping around.
          I have already ordered a replacement potentiometer, so that's not an issue.

          Now, I want to replace all three electrolytics on the PCB as they are CapXon and I don't trust them so much, I will replace them with something better while I've got the thing apart anyway.
          All are CapXon...
          10-21-2025, 05:39 PM
        • bauto601
          KDM 480W PSU upgrade succes! (opinions?)
          by bauto601
          Back in 2020 i bought a (2nd hand) compact ATX psu to replace my current one. My PC case only fits very short ATX power supplies so i didn't really have the choice of buying a decent 80Plus unit. The current unit is a modded YoungYear unit that i made a thread about a while ago:
          A "nice" YoungYear unit? - Badcaps

          The "new" unit is a KDM-M6480 480W psu, the 480W number is a typical KDM bullshit claim of course, but the 24A rating on the 12V rail seemed reasonable and the "Active PFC" claim gave me a bit of hope that this was going to be decent-ish....
          12-26-2023, 03:05 PM
        • dragon3x
          After updating motherboard capacitors, what to do next (Asrock K7VT2, SOLTEK SL-75FRN2L)
          by dragon3x
          Hi, I have some 32 bits computer motherboards that need repair, as they fail to
          power on.

          Here are some examples :

          (N.B. "capacitors" indicated here are electrolytic capacitors located in the onboard
          switching supply area).
          (N.B. #2 : I could not find a 3300 microF aluminum-polymer with a higher voltage
          than 6.3 V.)

          1 - Motherboard #1 : this is an Asrock K7VT2 (socket A) that still works well. To put it on test
          I replaced capacitors with aluminum-polymer.
          3300 microF/6.3 V. x 4 replaced by 3300 microF/6.3 V. (KYOCERA...
          03-21-2025, 02:46 PM
        • Loading...
        • No more items.
        Working...