Re: My Lisa need help !

In my experience, a pattern on the screen like that is due to the CPU not running or a bad memory board.

Do you have a memory board? If not, you need one.

However, even with no memory, the Lisa should beep to report the error... -- IF everything else is working properly.

Generally, if the pattern on the screen is unusual but isn't moving, then you are right, the video board is not the problem.

The empty socket is normal. That is for a simple mathematics processor that was never used (because it wasn't any faster than the CPU, as far as I can tell).

(And you are right, even with all those legs, the chips don't run very fast :)

The switch doesn't matter. It turns the batteries on and off.

Your ohmetre is called an ohm-meter in North America.

I'll look at an I/O board to see if the sound signal goes near the battery area. But, if the CPU isn't running, that would cause both the bad video and no beep symptoms.

Do you have any instruments besides your ohm-meter? A logic probe or oscilloscope?
If not, a good AC voltmeter might be sufficient to troubleshoot.

James

>I have checked with an "ohmetre" (how do you said that in english ?)
>the dirty connections on all the boards and they are ok.
>The switch below the batteries is stuck but on the "ON" position and
>the contact even if they look bad are ok. (this one i should replace i
>guess... if someone knows where i can find this piece).
>
>I have noticed that one is missing, BUT it should have been like this
>as i don;t see how the chip run away from the board ! :)
>
>Here the picture of the boards:
>
>Motherboard : http://i54.tinypic.com/2ue2vx0.jpg
>I/O board : http://i54.tinypic.com/wwc551.jpg and
>CPU : http://i56.tinypic.com/2vi381s.jpg
>
>As you can see i have worked well... But still not a success. :(
>
>About the screen, i don't believe it come from a potentiometer as i
>don't hear the "beep" sound at boot. The picture is not moving at all
>and the pattern is not changing at all.
>Screen : http://i55.tinypic.com/2a77tys.jpg

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