Help sought for an 8K7A+ with bad caps

Discussion in 'Epox' started by Leachim Sredna, Jan 25, 2007.

  1. Hi All,
    I want to fix at minimum cost and trouble an 8K7A+ which seems to have
    developed bad capacitors (some look quite bad and it's started random
    reboots and lock-ups -- see thread *Spontaneous reboots* in alt.windows98).
    I'm looking for somone who can supply a good replacement similar model board
    or who can replace the caps for me (I'm in France).
    I found another board on E-Bay but as it's in the US and described as
    "refurbished" I'm a little leery of paying so much carriage for that one.
    Help or ideas, anyone?
    Thanks in advance,
    Michael Anders
     
    Leachim Sredna, Jan 25, 2007
    #1
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  2. Leachim Sredna

    Davy Guest

    Could you not replace the caps.... should be easy enough do with a
    small 15 Watt soldering iron.

    If you should take this route use LOW ESR (Effective Series
    Resistance), or low impedance 105 deg. C types, do not use standard
    capacitors...!

    Obviously it's pointless if the capacitors have leaked and damaged the
    board, the gunge they spew 'could' eat away at the protective PCB
    lacquer then eat away the copper tracks.

    Davy
     
    Davy, Jan 28, 2007
    #2
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  3. Actually, I've solved the spontaneous rebooting problem for the moment by
    changing the PSU, notwithstanding the dodgy-looking caps, thanx !
     
    Leachim Sredna, Jan 28, 2007
    #3
  4. Leachim Sredna

    dave Guest

    Sometimes the caps can look bad and the board will still work. I have two
    8RDA+ systems. One began not booting up or having a hard time booting. It
    usually would boot after several attempts. I replaced the bad caps and that
    did cure it. The other 8RDA+ also has bad looking caps but continues to
    function properly to this day. Maybe the power supply in this machine is of
    better quality and gives better voltages so the bad caps aren't as big a
    problem. So for this reason I can see why the caps and the power supply are
    related. So the question is, did you really fix the problem with a new
    power supply? Maybe. Then again you may only have bandaided it.

    Replacing caps easy enough to do? No, not so easy. I have 22 years
    experience in electronics soldering and I struggled. It could have been
    easier if I had specialized tools. It's not a job for a novice.

    As to the job requiring special low esr, high temp caps? Not so. I used
    standard electrolytics of 85c temp and have absolutely no problems.

    DaveL
     
    dave, Jan 29, 2007
    #4
  5. Leachim Sredna

    Davy Guest

     
    Davy, Feb 26, 2007
    #5
  6. Leachim Sredna

    dave Guest

     
    dave, Mar 1, 2007
    #6
  7. Leachim Sredna

    Davy Guest

    I think it is you who dosen't know what you are talking about and you
    must be the only person what does such things...!

    Why do all mobo manufacturers not use standard 85 deg. C caps, they
    will sure save some cash, also why is it that you see 105 deg C low
    ESR caps in mobos... to make them look pretty? Please explain.

    It is clear if you are replacing these with standard types you are
    doing a sub-standard repair.... wonder what the manufacturer would
    think let alone your customers? It could be you are doing this so that
    the mobo keeps coming back for repair.... instead of doing a quality
    job.

    It is plainly obvious that a 85deg C component ain't
    gonna last as long as a 105 deg C type in a warm environment... you
    also can't see the reason for using low ESR types.... I doubt you even
    take their current ripple rating into consideration...

    .... you have been in the trade 22 years and can not see this point.


    Your gonna tell me you even use them in power supplies as well.. ?

    Oh... and to remove solder from a plated through hole in a multilayer
    board is easy.... [b:67d6a17884]and no [/b:67d6a17884]it's not trying
    to force the component leads through the holes which can do damage,
    you gotta clean the hole first and it ain't with a hot air tool, and
    desoldering braid is useless.


    Davy
     
    Davy, Mar 5, 2007
    #7
  8. Leachim Sredna

    Zephyr Guest

    I'm sorry, but all the hype is interesting read. I replaced all the caps on
    "my" computer [8K7A with 85 degree C caps [which by the way if your board is
    running over 185 degrees F., you got other problems] and have had no ill
    effects. I replaced them several years ago, and the board's been fine... no
    hiccups or BSOD.

    --
    Zyp
     
    Zephyr, Mar 19, 2007
    #8
  9. Leachim Sredna

    Davy Guest

    It's not just the ambient, ever thought what effect the ripple current
    has on a capacitor - especially if it's not low ESR.. ever wondered
    what made them go in the first place?

    They go even in a very cool environment not just computers and it
    ain't the age.

    So, it's ok then to swap a 105 deg. C hf type cap for a plain ol'
    standard 85 deg C. - sorry, I don't think so.

    Maybe you'll explain why they use them in the first place?

    Davy
     
    Davy, Mar 26, 2007
    #9
  10. Leachim Sredna

    dave Guest

    Davy,

    Here is the REAL reason they went bad:

    "The cause...
    This inferior and flawed electrolyte formula was used by a number of
    component manufacturers that sold to many different, reputable, and well
    known motherboard manufacturers. This problem isn't isolated to one
    particular brand of motherboard, and not even isolated to motherboards
    alone. I won't mention brands, but a VERY popular monitor manufacturer has
    been plagued with RMA's on some of their monitors that were built using
    these inferior capacitors. This problem has been reported in computer
    motherboards, monitors, televisions, radios, and stereo equipment. Through
    my experiences owning a service center, I've personally seen and serviced a
    large number of 'high-end' equipment that had prematurely failed
    capacitors."

    http://www.badcaps.net/causes/

    Read the above web page. It explains the "large-scale industrial espionage
    foul-up".

    DaveL
     
    dave, Mar 31, 2007
    #10
  11. Leachim Sredna

    Zephyr Guest

    I even saw larger 440v 50uf caps that explode. [New under warranty.] The
    environment they are subject too makes computer motherboards look like kids
    milk. Apparently, the electrolyte problem got into everything over the last
    several years.

    BTW: I replaced the blotted caps on my 8k7a a few years back and haven't
    had any trouble... been rock solid [both RAID 8k7a+ and the 8k7a boards on
    two computers.]
     
    Zephyr, Apr 1, 2007
    #11
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