Repairing An Explosive Compaq Portable I

Once again, I've been summoned to perform computer necromancy, in this case, in the form of a Compaq Portable I who my friend sirocyl "helpfully" brought to my apartment. The Portable I is an interesting piece of history given it was the machine that marked the end of IBM's monopoly over the personal computer, and was the first "fully compatible" IBM PC clone.

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While IBM would face early challenges with "functionally compatible" and "DOS compatible" machines, COMPAQ was the first to proudly proclaim 100% compatibility. In what would be a famous case of reverse engineering, Compaq fully documented and re-engineered the BIOS of the 5150, and created their own functionally identical replacement of IBM's code. This, combined with a licensed copy of DOS and GW-BASIC made the Compaq almost perfectly compatible with the 5150, with the only truly notable difference being the lack of cassette port. Compaq would also go as far to create their own clone of IBM's Color/Graphics Adapter in the form of the Video Display Unit, or VDU card.

This specific Portable was found on Goodwill Auctions by sirocyl in unknown condition. It's also one of the rarer, two floppy drive models, and a look at its system board shows that its one of the earliest revisions of Compaq Portable. Included is a full 256k of RAM, and BIOS chips from 1986.

When I got it, the Portable was entirely dead, and required extensive work even to determine what was wrong with it. This is also not including problems with the power supply, VDU card, or shorted capacitors which all made themselves known throughout the process.

Interesting Timestamps:
00:00 - Intro
01:00 - COMPAQ and the PC Clone Wars
02:50 - Initial Machine Exploration
05:45 - Machine Teardown
07:30 - Locating Short Circuits
08:40 - PSU Troubleshooting
13:10 - Exploring PSU Schematics
15:21 - Amateur Electrical Explanation
16:15 - C81 Capacitor Replacement
18:00 - Isolating New Faults
20:33 - Compaq Portable ATX Replacement
21:40 - Inspecting the Damage
23:00 - The Final Smoketest
24:05 - In Closing ...

Music provided by Epidemic Sound, in order of appearance:
- Chef Extraordinaire - Trabant 33
- Jam Street - T. Morri
- Thief - Rossier
- New York Minute - T. Morri
- Extravaganza - Jules Gaia
- Ain't No Thing But To Swing - Jules Gaia
- Midnight Swing - Jules Gaia
- Swagger Stagger - Lucas Pittman
- Feeling Alright - Gavin Luke
- Glitz At The Ritz - Jules Gaia
- Mama Swing - Lucas Pittman

#Compaq #VintageComputing #Restoration #Explosive