I picked up a Packard Bell PB286NB laptop from the early 1990s, and the main problem was simple enough at first: it came with no power supply. The machine itself was very clean, inside and out, and the rear label listed 7.5V and 5.6V input ratings along with a 20MB hard drive and 1MB of memory. It also had a surprisingly nice keyboard and a big NiCad battery pack that took up a lot of the depth of the case.
I spent a little time identifying the machine and found a 1991 review that matched the specs pretty well: a 12MHz 286, LCD display, VGA output, and a list price that was far higher than you’d expect for a fairly modest laptop now. Around the outside, the machine had spring-loaded port doors, a floppy drive, keyboard and mouse ports, video out, and an odd three-pin power connector that caused the whole problem in the first place. Those little hinged doors were exactly the sort of thing that liked to break, but most of them had survived.
Getting inside took a bit of poking around because the screws were hidden under panels and even under a warranty sticker. Once opened up, the layout was compact, with the hard drive, floppy drive, a daughterboard, and the main board packed in tightly. I found the Award BIOS, a Harris 286 CPU, a socket for a math coprocessor, and a pair of unusual memory modules with all the pins on one side. There was also a second battery inside, and the hard drive sat in a small caddy with a very short laptop IDE cable.
Since the original power brick was missing, I traced the power input as far as I could. The board was multilayer, so I couldn’t just follow every trace visually, but I did locate the CPU’s +5V line and worked back through the daughterboard connection to identify one side of the input. By feeding one of the suspected pins and checking where the voltage showed up, I worked out which connection corresponded to the lower system voltage and which one went toward battery charging.
With 5.6V applied, the laptop only lit a few LEDs and didn’t really come up. When I added the second supply for the other input, the screen flickered, the keyboard LEDs flashed, and after the battery had charged for a while the machine finally beeped and started to POST. It reached a boot failure message, and the hard drive spun up sounding very rough, but the LCD was alive and the controls for brightness and contrast worked.
Booting from floppy went much better. MS-DOS 4.01 loaded fine, the floppy drive read disks reliably, and FDISK reported no fixed disk present. I pulled the hard drive (Conner CP2024) and it was in bad shape, with sticky green residue on the casing, so I left it out and focused on getting stable power another way.
The workaround ended up being to feed 5V directly into the battery connection instead of relying on the original external power arrangement. I removed the side knockout, found a matching plug, wired it to a barrel jack, and made a short lead that tucked back inside when not in use. A small portable supply wasn’t enough to start the machine, but with a proper supply connected the laptop ran normally.
With the case back together, I tested the VGA output, external keyboard, and serial mouse, and all of them worked. The machine ran CheckIt, switched cleanly between LCD and CRT, displayed color properly on an external monitor, and loaded software and games from floppy including WordPerfect, Indianapolis 500, Lemmings, and Where in the World Is Carmen Sandiego.
The laptop ended up running well from the battery-connector power mod, and it stayed stable for hours. The hard drive was still out of service, but the Packard Bell itself was back up and usable.
— Aaron
Links
Timestamps
00:00 – Intro
00:58 – First Look
03:16 – Packard Bell Nostalgia
10:30 – Ports
14:06 – Disassembly
17:33 – Internals
20:46 – Power Troubles
30:07 – Bad Hard Drive
31:55 – Power Solution
36:11 – Demonstration And Games
49:27 – Wrap Up