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Thread: Help finding replacement capacitors for WD-L40S ESDI hard drive from IBM PS/2 55SX

  1. #1
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    Default Help finding replacement capacitors for WD-L40S ESDI hard drive from IBM PS/2 55SX

    Is there any chance someone can help me find some replacement capacitors?

    This WD-L40S ESDI hard drive from my IBM PS/2 55SX has leaky capacitors which I'd really like to have my local computer shop replace, but I cant find identical replacements to give them at the moment.

    The capacitors are pictured at the top, underneath the edge connector.

    Ideally, I need a UK supplier. If I'm honest eBay UK is usually fairly easy etc... I'd also ideally like identical replacements, but if they are no longer available I appreciate I may have no choice but to use compatible ones.

    The capacitors say:
    "47 16V 14I"
    "100 6V 22B"
    "47 16V 14I"

    From research I believe these to be SMD Aluminium Electrolytic capacitors.

    I'm guessing the middle value is voltage, 16V and 6V? The top value is capacity, 47uF? The bottom value, I have no idea what it is or if I need to match it.

    When searching I have found similar ones, but with slight discrepancies like 6.3V instead of 6V etc...

    Thanks!
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  2. #2
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    Quote Originally Posted by sh0dan View Post
    I'm guessing the middle value is voltage, 16V and 6V? The top value is capacity, 47uF? The bottom value, I have no idea what it is or if I need to match it.
    Apologies, it appears I've at least partially found an answer. It seems the bottom value may be a lot number and the information indicates 6V is in fact 6.3VDC. With that information I should be able to target my search more.

    https://macrofab.com/blog/the-footpr...ic-capacitors/

    Update: I've ordered these. Please correct me if they are wrong and before I blow up the drive

    "10x EEEFPC470UAR Capacitor electrolytic low impedance SMD 47uF 16V PANASONIC EW"
    "10x EEEFK0J101UR Capacitor electrolytic low impedance SMD 100uF 6.3V PANASONIC"
    Last edited by sh0dan; July 24th, 2018 at 09:05 AM.

  3. #3

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    The last numbers are likely date-codes telling when they were manufactured. In replacing electrolytics, you can be slightly over on voltage and capacitance but not under. If the style you selected (radial/axial/SMT) is correct, then you should be ok.

  4. #4
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    Quote Originally Posted by T-R-A View Post
    The last numbers are likely date-codes telling when they were manufactured. In replacing electrolytics, you can be slightly over on voltage and capacitance but not under. If the style you selected (radial/axial/SMT) is correct, then you should be ok.
    Thanks, I'll keep that in mind.

  5. #5
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    The capacitance should always be as close as possible, but the voltage is dependent on the circuit.

    Some manufacturers will use the same voltage value for a bunch of different voltage rails because it's cheaper to stock general capacitor values vs. specific capacitor values. An example would be PC power supplies which often use 10v rated caps for the 3.3v and 5v rails, when 6.3v will work better because of lower ESR. Sometimes 25v rated caps will be used for the 12 and -12v rails when 16v will work fine.

    In your case, the 6v rated cap is for the 5v rail and the 16v rated caps are for the 12v rail. You can use 6.3v as a replacement for 6v and keep the 16v rating for the new capacitors.

  6. #6
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    That's assuming all thing being equal. I've measured 35VDC caps with lower ESR than their corresponding 10VDC cousins. Same brand, same series (NCC).

  7. #7
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    Thanks both, I really appreciate the additional information and am keeping a list of snippets for next time I need to replace capacitors.

    I'm generally feeling happy now with the above reassurances. Hopefully it will give my PS/2 another decade or so of life!

  8. #8
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    Quote Originally Posted by Chuck(G) View Post
    That's assuming all thing being equal. I've measured 35VDC caps with lower ESR than their corresponding 10VDC cousins. Same brand, same series (NCC).
    Some caps have a single wound set of plates, while others have multiple sets of plates in series to get higher voltages. I've found the latter usually have higher ESR. I don't know if they also do them in parallel, as I haven't taken any apart with this configuration yet.

  9. #9
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    My takeaway on the test was that for typical small values of DCWV, it probably doesn't amount to a hill of beans for many applications (e.g. supply rail decoupling). It probably starts to get serious when replacing 10V caps with 50V or 100V ones. One could also go with the solid electrolyte variety, which claims a longer working life.

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