Re: More transformer data.

It should be pointed out that a game with the third prong cut off the power plug
will usually have about 55 volts on all the "grounded" surfaces. This is due to
the noise filter on the power line. The capacitors in it turn into a capacitive
voltage divider. Not a lot of current there, but can still give a nasty jolt if a
customer touches both that game and something that's correctly grounded.

Matthew Sell wrote:

> Isolated or not, you can still receive a shock from an ungrounded game if
> it is malfunctioning (bare wire contacting chassis, shorted component that
> is mechanically attached to chassis, etc.)
>
> Taking a quick peek at the Lunar Lander schematic I see an isolated input
> to the monitor, with the only two components receiving non-isolated
> supplies being the interlocks and the marquee lamp.
>
> - Matt
>
> At 10:52 PM 11/30/00 +0300, you wrote:
>
> >-----Original Message-----
> >From: John Robertson <jrr@flippers.com>
> >To: vectorlist@synthcom.com, vectorlist@synthcom.com
> >Date: Wed, 29 Nov 2000 09:01:45 +1100
> >Subject: Re[2]: VECTOR: More transformer data.
> >
> > > If you have a transformer that is listed as (for example) 36-0-36, then
> > you
> > > HAVE an isolation transformer. Unless the transformer specifically
> > > identifies itself as an "Auto-Transformer" then it is an isolation style.
> > >
> > > Look at the wiring diagram for the transformer in question. As long as the
> > > output windings are not connected to the input it is isolation (most
> > > transformers are isolation by the way). You can also do a resistance check
> > > if you don't have the wiring for the transformer. If there is infinite
> > > resistance between the line in and the output windings then this is an
> > > isolated transformer. If the resistance is around 20 ohms, then you
> > have an
> > > auto-transformer.
> > >
> > > The reason the discussion of isolation transformers comes up is that
> > > standard raster (sorry) video games' monitors are NOT line-isolated,
> > having
> > > no transformer in the primary. They assume that the application provides
> > > isolated power to the monitor.
> > >
> > > Clear as mud??
> > >
> > > John :-#)#
> > >
> >That sounds pretty fucked-up!
> >I am in europe, and we ALLWAYS use isolation transformers on the monitors.
> >If we didn't then we could get prosecuted for endangering public safety.
> >
> >I was not aware that in america people where stupid enough to just connect
> >monitors to the power-line.
> >I suppose that is why american manuals make so much of a point about
> >correct grounding of the machine!
> >
> >L8r.
> >
>
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--
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 Marion, IA  52302-3084
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