Gottlieb System 1 power supply Cap explosion

Archived from groups: rec.games.pinball (More info?)

I replaced all the electrolytic caps in one of sys 1 games and while I
was testing it c4 (1000mfd 35vdc) exploded in my face. (Thank god for
safety glasses). I know the cap was installed correctly... anybody
know what could cause this?

(CR4 - a diode (1a 100v 1n40002) reads like a short)
9 answers Last reply
More about gottlieb system power supply explosion
  1. Archived from groups: rec.games.pinball (More info?)

    If that diode reads as a short in circuit, unsolder and lift one lead
    and retest it out of the circuit. If it still reads shorted then it
    definitely is shorted.

    BTW, it is not uncommon for new components to fail right away. Happens
    all the time. That's why game manufacturers "burn-in" gameboards for
    several hours/days before shipping a new game.
  2. Archived from groups: rec.games.pinball (More info?)

    is it possible for a shorted diode to cause a cap to explode?
  3. Archived from groups: rec.games.pinball (More info?)

    i thought it would have needed to be backward too - it was placed
    correctly - as far as it was marked....
  4. Archived from groups: rec.games.pinball (More info?)

    I believe that a shorted diode could cause a cap to explode. It will
    take a bit longer than being in teh wrong way round.Depends a bit on
    the circuit.

    Check that diode out, and any others near it. Then replace the cap.


    Rob wrote:
    > i thought it would have needed to be backward too - it was placed
    > correctly - as far as it was marked....
  5. Archived from groups: rec.games.pinball (More info?)

    It's possible that the shrink sleeve on the capacitor was put on wrong,
    which led you to believe you were installing it correctly, and "boom".
    Looking at the lead positioning will sometimes tell. Sometimes one
    lead is longer. It's something I do after looking at the sleeve
    anyway.

    I agree with Ken. I've had new components give it up on power up. As
    far as a diode shorting and taking out a cap, it pretty much has to be
    in a circuit at the rail. Usually these types of circuits are designed
    with much overkill and current limiting for this very reason.

    Mario
    Pinthetic
  6. Archived from groups: rec.games.pinball (More info?)

    it took a few minutes of on time. i was testing all the pin-outs... and
    had tested a few before it popped. (it was loud as a firecracker!)
  7. Archived from groups: rec.games.pinball (More info?)

    The only way I have seen this is if the cap was in backwards.

    Maybe it was marked wrong?

    Jim Knight
    "Rob" <robbywj@gmail.com> wrote in message
    news:1124454782.441607.217650@f14g2000cwb.googlegroups.com...
    >I replaced all the electrolytic caps in one of sys 1 games and while I
    > was testing it c4 (1000mfd 35vdc) exploded in my face. (Thank god for
    > safety glasses). I know the cap was installed correctly... anybody
    > know what could cause this?
    >
    > (CR4 - a diode (1a 100v 1n40002) reads like a short)
    >
  8. Archived from groups: rec.games.pinball (More info?)

    Rob:

    If the wrong diode(s) shorted, you could have been
    presenting AC to the electrolytic cap, which could
    have caused it to overheat and explode.

    It's possible that it was marked incorrectly, but it's easy
    to make a mistake and install it backwards. Most of
    those big caps mark the "-" terminal, but most printed
    circuit boards mark the "+" terminal. So if your attention
    lapses for a second and you forget to reverse the marks,
    BOOM!. Glad you weren't hurt.

    -Mark
    --
    http://pinballpal.com/

    "Rob" <robbywj@gmail.com> wrote in message
    news:1124454782.441607.217650@f14g2000cwb.googlegroups.com...
    >I replaced all the electrolytic caps in one of sys 1 games and while I
    > was testing it c4 (1000mfd 35vdc) exploded in my face. (Thank god for
    > safety glasses). I know the cap was installed correctly... anybody
    > know what could cause this?
    >
    > (CR4 - a diode (1a 100v 1n40002) reads like a short)
    >
  9. Archived from groups: rec.games.pinball (More info?)

    Rob wrote:
    >
    > I replaced all the electrolytic caps in one of sys 1 games and while I
    > was testing it c4 (1000mfd 35vdc) exploded in my face. (Thank god for
    > safety glasses). I know the cap was installed correctly... anybody
    > know what could cause this?
    >
    > (CR4 - a diode (1a 100v 1n40002) reads like a short)

    If the shorted diode was allowing AC to reach the capacitor, I can
    believe it would heat up after a while and blow...it is getting
    reverse bias half the time.

    --Bob

    =======================================================================
    Bob Ellingson bobe@halted.com
    Halted Specialties Co., Inc. http://www.halted.com
    3500 Ryder St. (408) 732-1573
    Santa Clara, Calif. 95051 USA (408) 732-6428 (FAX)
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