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[nickpunt]

Just got the power and video boards of my MacXL / Lisa 2/10 recapped and it boots with two high beeps to this checkerboard pattern. I can't find any reference to this in any of the repair guides. Anybody have any idea what it might be? We've already tried reseating the boards.

Prior to recap it was getting to boot screen, the video was just flickering / unstable.

Thanks!

[sigma7]

two high beeps to this checkerboard pattern

The presumably unchanging checkerboard indicates the CPU Board is able to access memory to send it to the video board & display (with the display showing the semi-random state according to how the memory chips powered up).

Often there is no beep, indicating the 68K CPU isn't running at all (or there is no I/O Board to drive the speaker).

In this case, the two beeps indicate the 68K CPU is successfully running the code from ROM and accessing the I/O Board to make the noise, but the self test result is that there isn't any memory.

I think this suggests the fault is on the CPU board and the recap of the video board and PSU are unlikely to be the cause.

Were any changes made to the CPU board?

Suggestions:

- a detailed visual inspection of the CPU board, and
- see what happens if you power up without the I/O Board installed... if there is an image of the self-test instead of the checkerboard then it seems the I/O Board is interfering with access to RAM as in another recent thread.

[nickpunt]

Thank you so much @sigma7! More futzing around with reseating the M1 board and just got it to boot fine! I looked through the various repair manuals and hadn’t seen any mention of a checkerboard like this so it was a bit of a stumper. Hopefully this helps someone else out when searching!.

[sigma7]

reseating the M1 board and just got it to boot fine!

Excellent!

Note that the memory slots don't have to be filled in order: trying a single memory board in one slot then the other can be helpful to diagnose the "no memory" error.

In my personal experience, when a Lisa that used to work has a problem that appears at the self-test stage, it is often due to a poor contact at a card edge connector in the card cage, typically solved by slightly shifting the boards up and down (perhaps a few times, and perhaps leaving in a slightly different place than before), removing and re-seating (perhaps a few times), or inspecting and cleaning the contacts.

I suspect deoxIT or a contact cleaner with silicone or other treatment helps minimize such problems, but I don't know enough to have a particular recommendation.