Asus motherboard capacitor replacement

Discussion in 'General Electronics Chat' started by Nosferatu, Feb 22, 2018.

  1. Nosferatu

    Thread Starter New Member

    Feb 22, 2018
    1
    0
    Hi all,

    I have a Asus motherboard (rampage 4 extreme), for a while it has been slow to start, as in you press the on button and It may take between 20-45 seconds to start. Normally means failing capacitor.

    A week ago it stopped all together. Pressing the button doesn't do anything. Being a cable techy and a software engineer, my curiosity lead me to pull the board out and inspect it for damages. The most obvious being a 'burnt' looking halo underneath one of the capacitors. I am not genius, but it seems to me that the capacitor failed.

    I have spent hours trying to identify it to find a replacement but with no luck. So I am asking you guys to help me find it, and any tips in regards to inspecting and fixing the board would be appreciated!

    The markings on the cap read:
    fp 10k
    28bz
    101
    16

    Now I figured:
    101 = 100uf
    16 = 16v

    28bz seems to be a manufacturer code but I have had no luck finding the actual cap.

    FP - no clue.

    Photos are attached for reference.

    Any help will be very appreciated!

    Thanks in advance, Igor. 2018-02-23 00.57.35.jpg 2018-02-23 01.03.09.jpg
     
  2. GopherT

    AAC Fanatic!

    Nov 23, 2012
    8,025
    6,785
    The 10k means 10,000 hours at operating temp. You can upgrade to 12k if you want. Don't go lower.

    When selecting a cap, measure distance between pins. Make sure it is the same on new cap.

    Measure diameter and height of the cap. You need one that fits your space.

    Make sure you get a "radial" design with both pins on the same side of the can.

    You can try to get into ESR rating but many caps of 100 uF and smaller don't have a spec, the datasheet does not mention ESR. Lower is better if you have a choice.

    Can you see the manufacturers name on the side of the cap? Maybe we can track down a datasheet.

    On the other hand, if your new one fails, you know how to replace it. Right?
     
  3. dante_clericuzzio

    Member

    Mar 28, 2016
    212
    4
    I tried to replace capacitors on motherboard before and it wasn't so easy the desoldering and resoldering part if you have no experience of what kind of solder to use and its wattage as well as how to take it off the board without burning the electrical path would be new experience to explore for ya
     
  4. Janis59

    Active Member

    Aug 21, 2017
    579
    92
    Just take a cheap ESR measurer for some 10 USD from ebay. It allows to test electrolytes without of desoldering. It`s AC voltage is ca 60 mV what means none of p-n barriers are not even near to opening. Just go over the all electrolytes and probably some will be suspicious. Or none and then You know that it are not faulty. Normally the sharply increased ESR is the first sign that capacitor goes `caput`.
     
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  5. AlbertHall

    AAC Fanatic!

    Jun 4, 2014
    6,407
    1,490
    But in this case it looks like there are loads of capacitors in parallel and then measuring ESR in circuit won't tell you anything.
     
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  6. ebp

    Well-Known Member

    Feb 8, 2018
    1,859
    644
    From their appearance I think it is very very likely that those are "exotic" electrolytic capacitors. Such capacitors have extremely low ESR and therefore very high ripple current rating. The best of "conventional" electrolytic caps can't even begin to compete with them.

    ~~
    did a quick tap of intertoobz - Nichicon FP series seems likely
     
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  7. GopherT

    AAC Fanatic!

    Nov 23, 2012
    8,025
    6,785
    First step to removing them is to cut away any conformal coating then ADD leaded solder to the joint and melt it in to make an alloy mixture with a lower melting point. Then start removing solder with wick or sucker/desoldering station.

    Cutting the component and removing one lead at a time is also helpful.
     
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  8. ebp

    Well-Known Member

    Feb 8, 2018
    1,859
    644
    Removing through-hole capacitors from a typical motherboard can be extremely difficult. I've found it very difficult on some of the boards I've done and I have a great deal of experience, several soldering irons with a wide range of tips, power vacuum desoldering equipment and good hot air tools.

    The motherboard will be at least four layers and the capacitors will almost certainly connect to the inner layers via the through-hole plating "barrel". Sometimes this is done using a thermal relief design, sometimes not. Getting enough heat, without excessive temperature, to the inner layers is difficult. Preheating from the "solder side" of the circuit board with hot air can help a great deal - but you need a decent hot air tool and it takes some time. Pinpoint heating isn't helpful - you need to get a broad area of the inner copper fairly hot. A hand-held heat gun with variable temperature can be quite satisfactory and the large volume of hot air they deliver helpful. A temperature-controlled soldering iron (again, not too hot) with a broad tip that spans both pins can be helpful. If you pull too hard on the capacitor before the solder is completely melted you can pull the copper barrel out of the hole, which makes repair virtually impossible. Clearing residual solder from the holes is difficult. I consider solder wick to be almost useless for this task. If you are lucky, the holes will be quite large, which can make things considerably easier.
     
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