Bad/leaky cap?

Collapse
X
 
  • Time
  • Show
Clear All
new posts
  • ipman
    Senior Member
    • Jul 2011
    • 159

    #1

    Bad/leaky cap?

    Found this Lelon cap on the interface board of a LG W1934S monitor.
    The vent is covered with a redish thing and it's ESR is looking unusually: 0.36 ohms compared to another ones which are 0.13-0.16ohms.
    It's a Lelon branded 220uF/10V cap.
    Do you think this is a bad cap? Or a measurement error (altough I tested it more than 4 times).
    Attached Files
  • PCBONEZ
    Grumpy Old Fart
    • Aug 2005
    • 10661
    • USA

    #2
    Re: Bad/leaky cap?

    Looks like ink to me.
    Sometimes they mark caps as part of QA so they know some check or another got done.
    .
    Mann-Made Global Warming.
    - We should be more concerned about the Intellectual Climate.

    -
    Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.

    - Dr Seuss
    -
    You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
    -

    Comment

    • ipman
      Senior Member
      • Jul 2011
      • 159

      #3
      Re: Bad/leaky cap?

      There's no other cap on that board marked as such.
      But yes, maybe ink.
      My feeling is that I should change it, based on the reputation of Lelon brand, but I wanted a second opinion.
      I will remove it and measure the capacity also, ESR looks a bit weird when measured on-circuit.
      Anyway, never seen such a small cap failing. It's filtering a 5V line to a regulator, but is behind another bigger cap located on power board, this one being a 1000uF/10V low-esr according to manual.

      Comment

      • PCBONEZ
        Grumpy Old Fart
        • Aug 2005
        • 10661
        • USA

        #4
        Re: Bad/leaky cap?

        Look up what the ESR should be.
        Might not even be a low ESR cap.
        .
        If the others you measured are in parallel and you measured in-circuit it's the other readings that are off.
        .
        Mann-Made Global Warming.
        - We should be more concerned about the Intellectual Climate.

        -
        Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.

        - Dr Seuss
        -
        You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
        -

        Comment

        • Agent24
          I see dead caps
          • Oct 2007
          • 4951
          • New Zealand

          #5
          Re: Bad/leaky cap?

          That red colour doesn't look like electrolyte to me... it normally ranges from brown to yellow as far as I know.
          "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
          -David VanHorn

          Comment

          • PCBONEZ
            Grumpy Old Fart
            • Aug 2005
            • 10661
            • USA

            #6
            Re: Bad/leaky cap?

            Originally posted by Agent24
            ... it normally ranges from brown to yellow as far as I know.
            Except for Sacon FZ which leak what looks like Shredded Wheat.
            [And it probably is.....]
            .
            Mann-Made Global Warming.
            - We should be more concerned about the Intellectual Climate.

            -
            Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.

            - Dr Seuss
            -
            You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
            -

            Comment

            • Agent24
              I see dead caps
              • Oct 2007
              • 4951
              • New Zealand

              #7
              Re: Bad/leaky cap?

              That was a crackup! and it's funny because it's so true...

              Maybe they were trying to make some alcohol from their shredded wheat, failed, and decided to use it for capacitors instead?
              "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
              -David VanHorn

              Comment

              • ipman
                Senior Member
                • Jul 2011
                • 159

                #8
                Re: Bad/leaky cap?

                Today I've removed it from PCB. Now it shows values of 0.28 and slowly incresing with time. Afther just a few seconds it shows 0.31. Also, capacity measured with a multimeter (Fluke 189) is at first reading 220uF and slowly decreasing with time, in a few seconds is 213uF. Never seen that behaviour.
                Indeed, it's not lowESR type, just a standard cap. It's a 220uF/10V Lelon RGA series. But they do not specify ESR at all in the datasheet, unfortunatelly.
                There is no other cap in parallel.
                Two more pictures of the removed cap.
                Attached Files
                Last edited by ipman; 08-25-2011, 03:39 AM.

                Comment

                • PCBONEZ
                  Grumpy Old Fart
                  • Aug 2005
                  • 10661
                  • USA

                  #9
                  Re: Bad/leaky cap?

                  Originally posted by ipman
                  There is no other cap in parallel.
                  I was talking about when you measured the other caps you are comparing it to.

                  Your measurements say the cap is fine.
                  .
                  Mann-Made Global Warming.
                  - We should be more concerned about the Intellectual Climate.

                  -
                  Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.

                  - Dr Seuss
                  -
                  You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
                  -

                  Comment

                  • ipman
                    Senior Member
                    • Jul 2011
                    • 159

                    #10
                    Re: Bad/leaky cap?

                    The caps used as comparation were out of circuit, spare ones salvaged from various other electronic devices. Unfortunatelly, they are phisically bigger than this one, so they don't fit on it's place.
                    I will put it back, thank you.

                    Comment

                    • severach
                      Badcaps Legend
                      • Aug 2007
                      • 1055
                      • USA

                      #11
                      Re: Bad/leaky cap?

                      Originally posted by ipman
                      Now it shows values of 0.28 and slowly incresing with time.
                      You warmed it up with the solder gun. ESR goes up as it cools.
                      sig files are for morons

                      Comment

                      • ipman
                        Senior Member
                        • Jul 2011
                        • 159

                        #12
                        Re: Bad/leaky cap?

                        The cap was removed, allowed enough time to rest and then measured.
                        It was more than 1/2 hour between removal and measurement, so I think this interval is long enough.
                        Anyway, measured afther some time (hours) it shows the same behaviour.

                        Comment

                        • PCBONEZ
                          Grumpy Old Fart
                          • Aug 2005
                          • 10661
                          • USA

                          #13
                          Re: Bad/leaky cap?

                          Dude, it takes a few seconds for a meter reading to stabilize.
                          That's true of most all meters.
                          .
                          There is no current flow trough the leads then you attach the meter initiating current flow through the meter and leads.
                          Current is electron MOVEMENT. There is a TIME factor in any movement.

                          Do you really expect all the circuits in the meter it to be -instantly- stable and at nominal values the -instant- you connect it?
                          Electricity doesn't work like that.

                          A $200-$1000 ESR meter might stabilize fast enough you wouldn't notice the change but probably not even then.
                          .
                          .
                          Mann-Made Global Warming.
                          - We should be more concerned about the Intellectual Climate.

                          -
                          Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.

                          - Dr Seuss
                          -
                          You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
                          -

                          Comment

                          • ipman
                            Senior Member
                            • Jul 2011
                            • 159

                            #14
                            Re: Bad/leaky cap?

                            True for ESR.
                            But the Fluke meter is spot-on for most of measurements (capacitance). Tried with several caps. Altough a few microfarads cannot make a signifiant difference.
                            Sure, comparing a Fluke which cost hundreds of dollars, measuring quite a few times per second, calibrated against standards with an microcontroller-based ESR meter is not fair.
                            Last edited by ipman; 08-26-2011, 03:51 AM.

                            Comment

                            • ipman
                              Senior Member
                              • Jul 2011
                              • 159

                              #15
                              Re: Bad/leaky cap?

                              I've put that one back on the PCB were it belong.
                              It seems to be working, the weird problem was a bad contact in a lamp pigtail connector.

                              Comment

                              Related Topics

                              Collapse

                              • amijim
                                Lelon RXW MSI 694d repair !
                                by amijim
                                Hello Badcapers ,I am Amijim and I am about to change the caps on two ancient socket 370 dual motherboards from 2001 and I would like to you if the Lelon RXW low ESR caps I can find locally is a good replacement part.Also i would like to ask you what wuld be better ,change the original 2700μf caps to 3300μf or 2200μf? Thank you....
                                04-02-2022, 12:09 AM
                              • xnRS
                                Lelon quality
                                by xnRS
                                How good are lelon caps ? I see some people install RGA Lelons currently. Also could see some old posts where lelons are reffered as the badcaps.
                                11-27-2021, 02:45 PM
                              • samoelec
                                Trying to understand how to find best replacement cap for old parts.
                                by samoelec
                                Disclaimer: This is the first time I step into the realm of analog electronics and my natural language is not English, so please forgive me if I failed to use the correct terms when describing things.


                                Recently I purchased a Tektronix TDS1012, a 20 years old product for cheap and I thought it could be a nice opportunity for playing (i.e. recapping) and learn something in the process.
                                The power supply board is exactly the same from this post so I'll just steal it for now.

                                I'm trying to find replacements for all those Lelon electrolytic caps, but then quickly...
                                04-01-2024, 03:39 AM
                              • ziplock
                                Abit BE6-II motherboard
                                by ziplock
                                Greetings,

                                I have an Abit BE6-II motherboard that posts sporadically with the bare minimum components installed - CPU, RAM, PSU, and a Keyboard. I know it posts when the speaker beeps. Re-seating the components has no effect.

                                I thought the sporadic posting might be capacitor related. Upon inspection, non of the caps are bulged or leaking and they are all original. So, I pulled them ALL. While the ESR is OK, over half of them are leaking current between 1 and 2 mA. The biggest offenders are way out of spec, like a 1500uf / 6.3V measuring 2600uF and many of the 820uF caps...
                                04-20-2025, 02:09 PM
                              • LENOVO-A880
                                Suspected DWM156 D-LINK USB Adapter Mainboard With Leaky Transistor
                                by LENOVO-A880
                                Hello Badcaps.net,

                                Does anyone has any clues what the value of this SMD transistor(PIC01). I suspected it's a leaky transistor where the mainboard of this DWM-156 DLINK USB Adapter failed to read the SIM card whenever I tried to use it to access the internet service. BTW I have attached some of the photos of the adapter mainboard and other parts(PIC02,PIC03,PIC04) so if you guys have any ideas for fixing it you're always welcomed to post them here. THANKS AHEAD OF TIME..
                                ...
                                06-04-2018, 06:10 AM
                              • Loading...
                              • No more items.
                              Working...