Say \u201cHello, World\u201d to my new Zenith ZL-1 MinisPort laptop from 1989 with an 8088 running 8Mhz, 1MB RAM, and a backlit LCD display. Weighs just under 6 pounds.<\/p>\n\n\n\n The removable NiCd battery pack also provides the charge port connector. There\u2019s a slot next to it for an optional modem (hint: there\u2019s a TTL serial header in there for COM2).<\/p>\n\n\n\n There\u2019s some curious branding on this particular machine. Lumisys Lumicam is printed around the screen. Any ideas what this is? A film printer? Additionally, the original Zenith logo has been removed. All that\u2019s left is a ghost sign.<\/p>\n\n\n\n June 15, 2020<\/strong><\/p>\n\n\n\n The Zenith ZL-1 MinisPort was the only computer to use a 2\u201d floppy disk. I don\u2019t have any so here\u2019s a 3.5\u201d floppy next to the drive for comparison.<\/p>\n\n\n\n June 17, 2020<\/strong><\/p>\n\n\n\n I did manage to get the Zenith MinisPort to boot (though it constantly complains the CMOS battery needs replacing, even though I replaced it). But here\u2019s the BIOS and MS-DOS 3.3 booting from ROM! Its rather hard to photograph this screen.<\/p>\n\n\n\n A couple of oddities: first, I can\u2019t save BIOS settings to CMOS (reliably) like the clock and boot order. Curiously, the clock\/date fields seem to add 32 to everything I enter. Enter \u201c00\u201d it will change to 32. Enter \u201c2020\u201d it changes to 5252. Odd, right? Why is this?<\/p>\n\n\n\n June 18, 2020<\/strong><\/p>\n\n\n\n Another oddity with the MinisPort is under MS-DOS, If the screen reaches the bottom and begins to scroll, the character case on the whole screen switches from lower to upper case.<\/p>\n\n\n\n June 19, 2020<\/strong><\/p>\n\n\n\n Opening the Zenith MinisPort to have a look. The bottom cover comes off easy enough revealing the motherboard. I\u2019ve annotated my best guesses. Can anyone confirm the BIOS RAM location?<\/p>\n\n\n\n June 25, 2020<\/strong><\/p>\n\n\n\n Looking at the MinisPort internal power supply and there are signs of leaking capacitors.<\/p>\n\n\n\n Removing the three SMD caps first. Looks pretty awful.<\/p>\n\n\n\n Removed the large surface mount caps. They leaked too. The legs were bent in opposite directions making it very difficult. Strong dislike!!<\/p>\n\n\n\n June 26, 2020<\/strong><\/p>\n\n\n\n Started cleaning up the MinisPort PSU board with solder braid after removing the caps. The SMD pads cleaned up nicely. Maybe there’s hope yet?<\/p>\n\n\n\n June 27, 2020<\/strong><\/p>\n\n\n\n I also reflowed all solder joints that were corroded with plenty of flux. Next, I used a scratch pen to clean corrosion on copper traces under the solder mask. Thankfully limited to the surface. It\u2019s looking pretty clean now.<\/p>\n\n\n\n June 29, 2020<\/strong><\/p>\n\n\n\n Painted on new green overcoat on exposed copper traces. Ready for new capacitors.<\/p>\n\n\n\n Installed new caps and put the inductors back in. Looks decent.<\/p>\n\n\n\n Good news is the PSU works and powers the MinisPort! Bad news is it still behaves strangely. There\u2019s an internal memory test and it revealed a memory error at address B800:0000, bit 5. Any ideas how to map that to a bad part on the board?<\/p>\n\n\n\n July 3, 2020<\/strong><\/p>\n\n\n\n Scoping. I think I need a logic analyzer next. Any recommendations?<\/p>\n\n\n\n July 4, 2020<\/strong><\/p>\n\n\n\n Stymied by the memory problem on this board, I decided to get a second one. Luckily it has 2MB of memory and the modem card. Unfortunately the power supply also needs recapping and restoration. Solder shouldn\u2019t be white and fuzzy.<\/p>\n\n\n\n The caps are actively sizzling and leaking onto the board as I remove them. But they\u2019re out. Now to clean up.<\/p>\n\n\n\n Lots of flux and solder braid later and it\u2019s looking much better. There was one casualty : this SMD inductor came off as I was reflowing it. I cleaned up the bottom looking for pads but it disintegrated. Just two fine wires left.<\/p>\n\n\n\n Under a microscope, I added some adhesive backed copper squares to both sides, folded the wires onto them and soldered on Kynar wire pigtails. It still reads as an inductor!<\/p>\n\n\n\n![\"\"](\"https:\/\/biosrhythm.com\/wp-content\/uploads\/2023\/02\/1272280795529519105-EagMogEWsAIj40g.jpg\")
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