PDA

View Full Version : Compaq luggable, bringing it back to life.



Frank_Black
November 25th, 2014, 06:33 PM
Hi all, first time here. I dug an old (probably 1984ish) Compaq portable out of a closet at work. I plugged it in and turned it on, and the fan worked but nothing else seemed to work (no HD or screen activity). I'm thinking about opening it up and trying to get it functional again.

So, being only marginally literate in things electronic -- I can work a multimeter and swap out cards and memory modules but that's about it -- any ideas how difficult it might be to diagnose and/or fix? It's been sitting unused for at least a couple of decades.

I'm old enough to have used one of these when they first came out, but I never did. I had a 286 XT clone, so my experience with these things is a bit more than passing familiarity.

Thanks!

barythrin
November 26th, 2014, 05:34 AM
Welcome to the forums! There's probably a technical manual (http://www.minuszerodegrees.net/manuals/Compaq%20Portable_Plus_286%20-%20Maintenance%20and%20Service%20Guide.pdf)out there if you know which version you have in front of you. Compaq Portable is the full suitcase sized unit. The Compaq Portable Plus (also an extra purchase/upgrade) will have a hard drive, or the Compaq Portable II is slightly smaller but at least says II on it :-), the III is more lunch box shaped.

Fortunately it's just a regular PC so not too much special troubleshooting. Check your power supply voltages and make sure you're getting the proper +/-5v, +/-12v. Another simple check is also just verifying it's not the contrast/brightness knob being all the way on low. That document above should hopefully help.

Frank_Black
November 26th, 2014, 09:17 AM
Ah, thanks. It would be the Portable Plus because it has a HD. I tried to contract/brightness knob, so it wasn't that. I'll look through the manuals and then open it up soon.

Frank_Black
December 5th, 2014, 10:42 AM
Say, would this require a boot floppy before it would do anything?

I opened it up, saw no obvious disconnections and a little red light flashes on the motherboard when it is first turned on.

PhilipA
January 8th, 2015, 06:28 PM
That red light should come on and stay on. That's the indication you have a good supply to the board.

The fan is powered directly off the mains, it's a 110V AC device, so not a good indication of power to things.
It doesn't need discs to get it going.

I'd say definitely first, pull the power to the floppy drive(s), remove all the expansion cards and see if it'll power up.

Mine didn't it had a number of bad (shorted) capacitors across the power supply rails on a couple of the expansion cards and the motherboard.

If pulling everything out doesn't get you anywhere, try disconnecting the motherboard from the power connector also (under the power supply, a bit fiddly to pull off) and see in a darkened room if the picture tube neck glows when you turn it on.

If it does, the +12 is good, at least.

The capacitors that generally tend to fail on these are replaceable from Radio Shack (about $1.50 each) or any reputable online dealer such as Mouser. They are 10uF 16V but I'd recommend 10uF 25V to give a bit more overhead. Plain electrolytic ones are fine. All the ones on the +12V rail on mine had gone bad, the are little orange tantalum "orange drop" style.

There's a number on the motherboard by the power connector and a few if the middle of the board. You can usually see the failed ones, they've either blown open or cracked or gone darker brown.

--Phil