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Roland Huisman
November 28th, 2012, 01:38 PM
So the Xerox 820 II are the same computers right?
Well it's like twins, the first moment they look the same but they are not.

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My second Xerox 820 II I'd pick up a few weeks ago, needed some serious cleaning.
So I'd took all electronics out and put the case in warm water with soap.

The second 820 II seems to be an older one. Horrible to service. You need to
remove the monitor board to get the mainboard out. But you can not reach all screws.
So you leave the last one in and turn it a little so the mainboard can get out.

My first Xerox is very easy to service. No screws at horrible places.
This one is a newer model. The case is made of thin plastic which is decolorized.
The older one is made of very thick material like the floppy unit. This is a grey plastic
which is painted in white. The color is still very nice like the floppy unit.

But it is not only the material. The newer Xerox case is much bigger than the
older one. They had made a redesign for serviceability. This made the machine bigger.
Here you can see the top cover of the new one on the older model:

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You can also see a little difference in the shape of the case. Also the grey mask
around the CRT is different. One is inside the case, the other in the front.

The older one had also some hand made modifications on the PCB.

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The bios versions are the same for both machines.
I'd thought it was fun to see how they had improved the machine in details.
But if I ever sell one I think it will be the newer one and keep the old one.

Regards, Roland

xmechanic
December 24th, 2012, 01:10 PM
Interesting.:) What year(s) are yours? Mine was produced Nov. 1984 and is different again from both of those.

Dave

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Roland Huisman
December 25th, 2012, 03:57 AM
The 'old' one is from September 1984 and the newer
somewhere in 1985 but I don't remember exactly.

Yours is very nice having the black mask. Does is have also
the hand mod's on the mainboard? And does it have also
the thick and heavy case material?

Regards, Roland

xmechanic
January 30th, 2013, 11:01 PM
Yes, it does have the heavy fiberglas case. As far as the custom mods on the mainboard, I don't remember right off if it does. Next time I pop the top off of it, I'll check. I need to go back into it at some point and see what's going on with the H.V. flyback transformer. It starts that high-pitched squealing thing after it's been on for a half hour or so. Very annoying, and I'm sure it's not helping anything either. ;)