what is the voltage tolerance for a iie?

[jonnosan@gmail.com]

Howdy folks,

I recently bought an apple iie off ebay (it's my first apple ever - we
had BBC's at my school)

Unfortunately when I unpacked the apple and plugged it in, it seemed
to be DOA - the screen was always a periodically changing jumble of
blocks (photo at http://www.flickr.com/photos/jonnosan/494345448/ ).
keypresses made no difference, nor did pressing reset (alone or in
combination with other keys)

I tried removing all the cards, cleaning the motherboard and reseating
all the socketed chips, which made no difference, and reading a few
posts on this newsgroup led me to suspect the most likely cause was
bad RAM. When I told the vendor the problem I had and my suspicion it
was the RAM, he very generously offered me a new mother board, which
he tested thoroughly before sending it to me.

However when I got the new motherboard and plugged it in to the power
supply and keyboard from the original machine, I got the exact same
result.

So I've either some bizarre coincidence (or something in the way I've
handled them) has caused both motherboards to fail in the same way, or
there's something else causing the problem.

Could it be the power supply? I don't know much at all about
electronics, but I got out a multimeter and read the voltages on the
plug (this is when the cable is not plugged in to a motherboard). The
values I got where slightly different depending on which of the two
grounds I used.

The values for ground 1 were: +5.33v, +11.23v, -11.59v, -4.98v
The values for ground 2 were: +5.31v, +11.20v, -11.56v, -4.96v

Are these values 'close enough' to the specified +5v,+12v,-12v,-5v? Or
should I assume a faulty power supply is the cause of my problems?

Regards

Jonno