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Thread: Another call to electronics people

  1. #1
    Bradfo69's Avatar
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    Default Another call to electronics people

    Ah, the joys of dealing with this stuff when you have very limited electronics knowledge. It's been a day of repairs... car... leaking haze machine... and now, I pulled out my variable DC power supply (kinda like this one but not exactly)

    http://www.ebay.com/itm/MASTECH-HY18...item4aab3781d6

    It hasn't seen the light of day since SELEM. Took it out of the box, plugged it in (didn't even have the leads attached), flipped on the power switch and "pop"... followed by a touch of smoke. Not electrical smelling smoke, more like frying insect so, I thought perhaps a bug had gotten inside and met it's demise but alas, it was a JAKEC 4700uF 35V capacitor. I can get a replacement and solder it in o.k. (I'm not *that* challenged) but, more importantly, is this just a fluke? There was nothing wrong with it the last time it was used and, it was just put right back in the box and sat on a shelf since then. Could there be something else I should check or, will just replacing the capacitor probably fix it and be fine?
    I bought it new less than a year ago and have probably used it three times for all of 15 minutes.


    Thoughts?

    Thanks!

  2. #2
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    It probably didn't like the input surge an may have already been
    on the edge... I would replace it with a slightly Higher Voltage
    same capacity type in case the voltages across it are close to
    the rated voltage...

    I always use Caps rated at least twice the voltage of the circuit..
    Also look for any other burnt parts...


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  3. #3
    Bradfo69's Avatar
    Bradfo69 is offline Pending BST Forum Purchases: $47,127,283.53
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    Thanks Jerry,

    I saw one online but it was 50v. And all of like $.89. Would that be safe to replace it? (I can't wait to find out the shipping on a $1 part!)

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    Yeah, 4700-5600uF / 50V capacitor would be good. Get a good name-brand (e.g. Mallory or Nichicon as opposed to cheap $1 part) If AC is applied to an electrolytic cap, it'll pop. Check for a shorted bridge rectifier too.

  5. #5
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    Quote Originally Posted by steve-o View Post
    If AC is applied to an electrolytic cap, it'll pop. Check for a shorted bridge rectifier too.
    Some of the best lab fun I have ever had has been exploding electos when wired to a lab supply reverse polarity and with heaps of volts!!! Some go right off!!!!

    When I was a youngin in the workshop, I embedded one in a tomato, and set it off when the office receptionist came in to the lab!!! Messy!!! She pissed her self!!!
    This space for rent.

  6. #6
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    Yeah, capacitor fun. Can't get enough of that

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