Repairing the Commodore 386SX-LT

Recently I acquired a second Commodore 386SX-LT, complete with power-supply, laptop bag and the original disks.
The only problem was that it didn’t seem to boot-up anymore: the screen would display the BIOS-screen and then complain that there was no system disk present.

My first 386SX-LT had taken a turn for the worse as well, as it too refused to boot past the BIOS-screen and then produce a strange noise which seemed to come from the HDD. It looked like the two laptops were in need of a HDD replacement.

I found a replacement HDD which seemed to be compatible (the BIOS did not list an “auto-detect” and the highest possible HDD size was 124Mb) on eBay, which was actually a HDD from an old Amiga 1200 system (to be precise, it was a Toshiba 124 Mb, which even came pre-installed with Workbench).

So, earlier this week, I got to work on fixing the two Commodore laptops. First up, was the “new” machine I got. I assumed the HDD would still be OK, it probably was just “missing” from the BIOS. To select the appropriate drive, I wanted to check for myself what drive was in the system, so I would need to get inside the 386. Opening the 386 was quite easy. You just needed to remove the 3 screws at the bottom and the keyboard pops off.

There it was, the Western Digital Tidbit 60 (WDAH260), a 62,3 Mb. All connectors were still in place, so from that perspective, all was OK. I put the keyboard back in place and got to work on the BIOS. Finding the appropriate drive was quite easy in the BIOS listing and a few minutes later, DOS was booting.
A funny sidenote was the setting of the system time.  I wanted to update it to the current date/time, so since I needed to provide it in the following format yymmddHHMM, I set it to 1201242110.  This was not something the BIOS could cope with… they probably never intended it to work beyond the year 2000… hello Y2K.

I was surprised to find a series of application on the drive, all still in good working order like WordPerfect and a couple of games, including Broderbund’s driving game “Stunts” – Nice!!

On to the next laptop. Here, I would definitely have to replace the HDD as removing the keyboard only made the strange noise more prominent. The same WDAH260 drive was inside, so quickly replaced it with the “new” Toshiba drive and booted the system. I selected the largest HDD in the BIOS, inserted the MS-DOS 5.0 disk and rebooted the computer. Strange rattling noises came from the floppy-drive… the disk was bad…
Luckily, I still had a set of MS-DOS 6.22 disks and attempted to install these. Swapping the disks during the installation reminded me of the many times I installed this OS on computers in one of my first jobs… time sure flies and technology advances quickly if you compare the whole disk swapping exercise with the installation procedures we have today via DVD or web.

Last disk out and then a quick reboot and… it worked! I was greeted with the C-prompt. Time to try the next phase: get Windows 3.1 on the system. Here again, a lot of disk swapping, with the first 3 disks operating in DOS-mode, followed by the next disks running inside the Windows-shell. All-in-all, a quite relaxing operation, which resulted in the old Windows 3.1 loader, followed by the all too familiar classic Windows 3.1 windows and menus.

Time then to start the 2 systems side by side, just like they would have been used, somewhere in an office, at home, … 20 years ago. Welcome back guys!

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7 Responses to Repairing the Commodore 386SX-LT

  1. Valerio Grisoli

    Hi, have a similar problem. Kept my Commodore Dos in my room at work (Univ. of Torino), even forgot it was there. I couldn’t remember the specs, the Operation Guide says C286-LT, DOS 4.01, RAM 1-5 MB, HDD 20 MB, but I’m not actually sure of what I got in that Basel shop :). Well, at the moment it doesn’t find the hard disk, with most certainly TurboTeX etc etc. I’m very interested in your page, if you like I’ll let you know what happens to the splendid machine. Bye!

  2. Robby "The C= guy"

    Hi Valerio,
    Yes, please keep me posted on how you progress. Do you have pictures of the machine as well?

  3. mine shows only 640Kb RAM, how to upgrade it?
    can we use modern IDE HDD?

  4. Robby "The C= guy"

    I don’t think you can use a modern HDD, as the BIOS only “knows” drives up to 124Mb.

  5. Thanks Robby,
    I’m also missing the flexible flat cable (FFC) for HDD. Do you know, by any chance, where to buy it?

  6. I have a C386SX-LT,

    had a HDD fault, fixed that and it worked great,
    then one day display went bad….lines across the whole display

    I have changed the electrolitic capacitors on the internal PSU as they were all leaked out,
    also the ones on the small pcb right next to the display
    No luck still the same issue

    I checked the flat cable its good also the connector on the motherboard is good,
    Checked the signal bunch of cables going to the display also good

    This would have to be some issue with the display pcb (the one behind the display)

    Any suggestions?

    Thank you very much for any info

  7. I found one of these in the attic of a house we bought. Would anyone like to buy it?

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