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27KD10
Are you sure that there isn't an extra number on the end???
I have a strong feeling your getting the wrong part. You need to find the specifications on that varistor, as I was unable to find any specs what-so-ever on the number above.
If you don't get the correct type, it could blow as soon as you power up your PSU or it won't provide any protection at all.
Please find out the ratings on that varistor before you buy one.
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I also buy 3AG for the fuse and buy one 3A and one 5A cause I don't know which is suitable with the current in the xbox.
Have a look at the picture below, it shows the location of the fuse rating.
Also, make sure the fuse is a
slow blow type and NOT fast blow. Otherwise it will go open circuit as soon as you power up the X-Box.

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tend to buy a 220V-to-110V changer but, again, I don't know how many watt (Power P) and how many ampere (Current I) is suit ? They have 50W and 100W type but I am afraid I need the bigger one ?
A 300W step-down transformer would be about right.
Please let us know the varistor specs before buying any.
Regards,
DarkMatter