Update.
Taking 0300FF at face value, I pulled the RAM, inspected the SIMM slots, blew them out again with canned air, and re-installed the RAM in reverse order, ie the former slot 1 SIMM became slot 4 sIMM, and so on.
Restart. No change in the mucky screenful of short vertical bars, but Sad Mac now reported 03FFFF. Noticing also that the mucky pattern on the screen varied with the brightness control, I wiggled the mains plug at its input socket to the Plus. The pattern changed continually as I wiggled, so here was aha! number 1. I replaced the mains cable, albeit that it had never misbehaved before, and voila! No more screen junk.
Presuming that the Plus really did not like its F-ing RAM (above), I then replaced the 80ns SIMMs with 9-chip 100ns SIMMs. Aha! number 2 followed. Restart was poifeck, with clear chime followed by raster followed by pointer followed by Quizzical Floppy. Don't ask me why, because I've never seem a Mac complain that its RAM was too fast, at least not until now. It is just possible that the SIMMs had been misdiagnosed as 1MB each when they are in fact 4MB, but that can be checked later. Anyway, the Mac was now ready for a startup disk. Happily it ingested a System 6.0.3 Macintosh System Tools diskette, read it, thought about that, and then spat the disk out, showing a Cross Floppy.
OK, you picky little beast. Try this System 5 Tools Disk #1 of 2. It booted, opened the volume, showed me its RAM as 4096kB in ATM, opened its System Folder, read a Read Me, and generally behaved itself.
It lives. Next will be to investigate the Rodime drive, and to try the Apple HD20 belonging to my 512Ke, as well as a SCSI drive that I am preparing for the 512Ke. The seller of this Plus may not miss the Plus any more, but may be pleased to hear that it 'does work'.
de
Taking 0300FF at face value, I pulled the RAM, inspected the SIMM slots, blew them out again with canned air, and re-installed the RAM in reverse order, ie the former slot 1 SIMM became slot 4 sIMM, and so on.
Restart. No change in the mucky screenful of short vertical bars, but Sad Mac now reported 03FFFF. Noticing also that the mucky pattern on the screen varied with the brightness control, I wiggled the mains plug at its input socket to the Plus. The pattern changed continually as I wiggled, so here was aha! number 1. I replaced the mains cable, albeit that it had never misbehaved before, and voila! No more screen junk.
Presuming that the Plus really did not like its F-ing RAM (above), I then replaced the 80ns SIMMs with 9-chip 100ns SIMMs. Aha! number 2 followed. Restart was poifeck, with clear chime followed by raster followed by pointer followed by Quizzical Floppy. Don't ask me why, because I've never seem a Mac complain that its RAM was too fast, at least not until now. It is just possible that the SIMMs had been misdiagnosed as 1MB each when they are in fact 4MB, but that can be checked later. Anyway, the Mac was now ready for a startup disk. Happily it ingested a System 6.0.3 Macintosh System Tools diskette, read it, thought about that, and then spat the disk out, showing a Cross Floppy.
OK, you picky little beast. Try this System 5 Tools Disk #1 of 2. It booted, opened the volume, showed me its RAM as 4096kB in ATM, opened its System Folder, read a Read Me, and generally behaved itself.
It lives. Next will be to investigate the Rodime drive, and to try the Apple HD20 belonging to my 512Ke, as well as a SCSI drive that I am preparing for the 512Ke. The seller of this Plus may not miss the Plus any more, but may be pleased to hear that it 'does work'.
de