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>
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> Go find a real computer.
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> NO CARRIER

Compaq Portable 486c Restoration

2026-02-21

A documentation project tracking the restoration of a Compaq Portable 486c/66 — a luggable 486-era PC with a built-in 10.4” TFT display.

Machine Specifications

ComponentOriginalUpgraded
CPUIBM Blue Lightning DX2-66 MHzAMD Am5x86-P75 (133 MHz, 4x multiplier)
RAM4 MB32 MB
Hard Drive210 MB Conner 3.5”This still works!
DisplaySharp LQ10D016 10.4” TFT (640×480)Sharp LQ104V1DG51 10.4” TFT (640×480)
AudioNoneSound Blaster AWE32 CT3900 (EISA slot 1)
Expansion2× EISA slotsSCM ISAC2PR10 PCMCIA adapter (EISA slot 2)
PCMCIA—Cisco Aironet 350 (WiFi) + SanDisk CF adapter
Floppy3.5” floppy drive—
ArchitectureSmall backplane with CPU card + RAM—

Restoration Log

1. PSU Rebuild

First step was to rebuild the PSU — it worked but stank like leaking capacitors. Without a stable power supply, any other restoration work would be unreliable. I can replace capacitors here and there, but I don’t trust myself enough to do the whole thing with confidence.

I outsourced rebuilding my PSU to GiGaBiTe on the Vintage Computer Federation Forums. They did a great job and the power rails are rock stable. The bridge rectifier and all electrolytic capacitors were replaced, along with the DPST power switch and a new cooling fan.

Full PSU rebuild documentation →

2. Screen Replacement

The original Sharp LQ10D016 display was damaged beyond repair due to leaking capacitors. This is very common with these. A replacement Sharp LQ104V1DG51 was sourced and adapted to work with the proprietary graphics card. This involved building a custom pin adapter cable, constructing a BLANK-to-Data-Enable delay circuit on the video card, and installing a modern CCFL inverter for the backlight.

Full screen replacement documentation →

3. Keyboard Restoration

The keycaps had the typical vintage yellowing from UV-degraded ABS plastic. I retrobrighted them using the heat method — simmering the keycaps in SalonCare 40 Volume Creme Developer (12% hydrogen peroxide) on the stove at low heat. Heat replaces UV light as the catalyst and provides more even results since all surfaces are submerged. Credit to The 8-Bit Guy as my source for the technique.

The keyboard cable is a very proprietary connector and becomes brittle with age. Mine was damaged but still usable after taping it up. A custom coiled replacement cable is planned.

Full keyboard restoration documentation →

4. Hard Drive Replacement (Future)

The original 210 MB Conner 3.5” hard drive is, against all odds, still working perfectly. This thing has been spinning since the early ’90s and shows absolutely no signs of stopping. It owes me nothing. Every time I power on the machine I half-expect to hear the click of death, but instead it just boots right up like it’s 1993 and it has something to prove.

When the day inevitably comes - and it will, because spinning rust doesn’t live forever no matter how stubborn it is - the plan is to replace it with an IDE-to-CompactFlash adapter. Dead silent, no moving parts, boots faster, and the CF card can be swapped out on a modern machine for easy file transfers. It’s the most popular hard drive replacement in the retro community for good reason.

But until that drive actually dies, I refuse to fix what isn’t broken. I will not be the one to end its career. That Conner has earned its retirement on its own terms.

Beyond Restoration

Processor Upgrade to AMD Am5x86-P75

The original IBM Blue Lightning DX2-66 was replaced with an AMD Am5x86-P75 (AMD-X5-133ADZ), a drop-in Socket 3 upgrade that delivers Pentium-75 equivalent performance at 133 MHz. The ADZ variant was chosen for its 85°C maximum case temperature rating — critical for this compact case where only a passive heatsink fits. The Compaq has no clock multiplier jumper, so pin R17 (CLKMUL) on the CPU had to be manually grounded to enable the 4x multiplier and reach full 133 MHz speed.

Full CPU upgrade documentation →

EISA Expansion

The Compaq Portable 486c has two EISA card slots — not a lot of real estate, so every slot counts!

Sound Blaster AWE32 IDE/MKP CSP (CT3900)

The Compaq has no onboard audio, so one EISA slot is dedicated to a Creative Sound Blaster AWE32 (CT3900). This gives full Sound Blaster and AdLib compatibility for DOS games, OPL3 FM synthesis, and the EMU8000 wavetable synthesizer with 512 KB onboard sample RAM. The CT3900 was chosen specifically because it is not Plug and Play — in 1994, “Plug and Play” mostly meant “Plug and Pray.” The CT3900 uses jumpers, works at boot, no drama!

Full Sound Blaster documentation →

SCM ISAC2PR10 ISA PCMCIA Adapter

PCMCIA was designed for laptops — but nobody said a 25-pound luggable couldn’t crash the party! The second EISA slot holds an ISA PCMCIA adapter card (SCM Microsystems ISAC2PR10, Vadem VG-469 chipset) providing dual PC Card slots. Why waste an EISA slot on one device when you can turn it into two hot-swappable expansion slots?

The dual slots open up the wide range of 1990s PC Cards — network adapters, flash storage, modems, and SCSI controllers.

Currently installed:

Previously I used a Xircom RealPort Ethernet 10/100 (RE-100), but it hogged both slots. Greedy.

Full PCMCIA adapter documentation →

Datasheets

References

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