Re: My Lisa need help !

On 3 Nov., 14:24, Bernard <bernard.s..._at_email.domain.hidden> wrote:

> I had the very same pattern on the screen that before :http://i55.tinypic.com/2a77tys.jpg

This is not the stuck-at-reset pattern. You get the background and some kind of menu bar. So your CPU is running and executing code from the EPROMs. Maybe you even get the first clicking sound from the selftest routine?

>From now there are many possible root causes. From my point of view,
it is most likely that the fault is on the CPU board, in the memory interface (MMU). You swapped the memory board, so a faulty RAM bank can be excluded.

The easiest way to isolate the fault is swapping boards with a working system. Swap the video state prom, too. Everything else requires an oscilloscope and logic analyzer.

As recommended in other replies, reseating the socketed chips, cleaning the connectors and checking the EPROM contents (you can reprogram them without erasing) will help in case it is not a faulty logic chip.

Patrick

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