General Category > Lisa Troubleshooting and Repair

Apple Lisa PSU error 47 on cold boot

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ried:
Update: Solved. If a LisaDAC expansion card is located in slot 1, error 47 appears upon cold boot when the new PSU is in the machine. If the LisaDAC card is relocated to slot 3, there is no error.

Someone in the community is producing a new Apple Lisa power supply, using new all new case materials and components. I purchased a unit from the initial run and have been testing it in a few Lisa configurations including the Lisa 2/5, 2/10 and Macintosh XL.

Upon cold start, the Macintosh XL gives an Error 47 at the end of its power-on self-test. It gives the option to restart and, when I do, it runs through the POST once again and no error appears. Error 47 only appears upon cold start in the Macintosh XL. Any idea what it could be flagging? Is it testing something in the 3A/88 ROMs that might not be present in H/A8 or H/88?

Again, the Lisa 2/5 and 2/10 are not showing the error with this PSU under any conditions. Returning the original PSU to the Macintosh XL resolves the error.

Gallery: https://imgur.com/a/DaSnn0M








And the error in the Macintosh XL:

ried:
In case it matters, the Macintosh XL features an original 16MHz XLerator with SCSI, PFG, X/ProFile, etc. Again, no errors at all with the original PSU. With the new PSU, error 47 appears with a cold start only, and does not appear during a restart. After error 47 appears, I can also choose "Startup from..." and boot normally with no issues.

anotherLISAguy:
Did you have a look through the board designers notes.
The layout looks identical to the LisATX - Pico ATX PSU Replacement
https://github.com/warmech/lisa-hardware/tree/main/LisATX%20-%20Pico%20ATX%20PSU%20Replacement

Looks like they went to the trouble to do the branding and toughened up a couple of spot.
Do you have a link to the reseller.
Had considered building my own (all the plans are there)

Keep us posted as I am sure others would find an alternate PS a great base unit to bench with.

As for a late thought on the issue, since it goes through everything and at the end 47s you - a semi-educated guess would be some added code/reliance added to the XL ROM (assuming all other things equal)
whether the 'original 16MHz XLerator with SCSI, PFG, X/ProFile, etc' are adding any additional checks/flags is another

stepleton:
Silly question but does your PSU replacement provide a reliable +5V standby power? I'm wondering if your RTC and parameter RAM are taking on random/invalid values each time you restore power after turning the machine off.

A different but very related question: do you find that the Error 47 occurs with an original PSU after you unplug the Lisa and plug it back in?

AlexTheCat123:
It might also be worth trying things without the XLerator and PFG to see if that helps at all.

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