Re: Power supply

[mjmahon@aol.com (Michael J. Mahon)]

Leon Jacobs wrote:

>I'm trying to get an Apple II europlus going. It turned on once and
>after that, when i flicked the power switch I saw a spark near the
>switch and it tripped my plugs circuit in my office.
>
>Now it does that every time I flip the switch. How can I fix this?

You have a short in the power supply.  Either there is no fuse
or the short is before the fuse, since it repeatedly trips your
breaker.

There are several components that can produce this kind of
short, but many of them will cause other faults as a result of
the original short.  ;-(

The line bypass capacitor(s), the diode bridge, the line-side
filter capacitors, the switching transistor(s), etc., are all possible
causes.

At this point, you will need to check almost the entire line-side
of the supply, component by component, to make sure that the
_consequent_ damage doesn't cause any replacement parts
to fail.

Or, you can assume that if it isn't one or two easy to replace
things, then it isn't worth pursuing anyway, and try replacing
the easy ones and hope for the best.

(Have you ever noticed how replacing a fuse in a switching
power supply usually results in just another blown fuse?)

>Also, I've looked through the collection of floppy disks and can't
>remember if the actualy DOS is coded into the ROM, or if you need a
>system disk to boot it up.

DOS (or ProDOS, or Pascal, or ...) is booted from the disk drive.

DOS 3.3 is on lots of disks (since most DOS disks are bootable),
but disks with other operating systems are also widely available.

-michael

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Home page:  http://members.aol.com/MJMahon/