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Gottlieb System 1 power supply Cap explosion

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  • Power Supplies
  • Games
  • Video Games
Last response: in Video Games
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August 19, 2005 9:33:02 AM

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)

More about : gottlieb system power supply cap explosion

Anonymous
a b ) Power supply
August 19, 2005 12:12:47 PM

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.
August 19, 2005 3:42:40 PM

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

is it possible for a shorted diode to cause a cap to explode?
Related resources
August 19, 2005 4:48:19 PM

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....
August 19, 2005 4:55:08 PM

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....
Anonymous
a b ) Power supply
August 19, 2005 5:22:07 PM

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
August 19, 2005 5:48:24 PM

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!)
Anonymous
a b ) Power supply
August 19, 2005 6:59:53 PM

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)
>
Anonymous
a b ) Power supply
August 20, 2005 3:36:14 AM

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)
>
Anonymous
a b ) Power supply
August 20, 2005 6:18:13 AM

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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