Mark,

Look at the blown fuse.  If the metal wire simply melted, then you have an
excessive current draw.  If the inside of the glass is blackened (most
likely problem), then you still have a short to ground.   Best guess is that
your inadvertent short created another short inside the power supply.

Jim Meagher
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----- Original Message -----
From: Mark Rode <[log in to unmask]>

> I was experimenting with a device I made  using the 12 volt leg of one of
> my AT power supplies as the power source. I inadvertently shorted the PS
> out...I know the cause..... and blew the PS internal SAE 4A 250VAC fuse.
>
> I had  a SAE 4A 120V fuse that I soldered on the board thinking that in as
> much that I will never flip that 250 volt setting switch on the back of
the
> PS and  would always  run at 115volts AC the fuse should be fine. However
> when I powered on I got a big blue light  and fuse was gone. Obviously I
> need a 250 volt fuse...but why if I am inputting 115 V AC?
>
> m
>
>                          PCBUILD's List Owner's:
>                       Bob Wright<[log in to unmask]>
>                        Drew Dunn<[log in to unmask]>
>

                         PCBUILD's List Owner's:
                      Bob Wright<[log in to unmask]>
                       Drew Dunn<[log in to unmask]>