Revive a Prehistoric Dinosaur... an IBM PS2 55SX !





Introduction: Revive a Prehistoric Dinosaur... an IBM PS2 55SX !

This instructable involves physically hacking open a Dallas DS 1287 assembly, and also rigging an older ATX style power supply to work with an IBM PS2 55SX.

Since I discover a lot of information along the way, I would recommend reading the entire instructable before attempting to do anything shown here.

Doing anything to, or even looking at an old computer could cause it to stop working. Please do not attempt anything unless you are aware of the possible results:

A computer that is still broken, broken even worse than before, fire, smoke, etc.

I am now (painfully) aware that similar work on the DS 1287 has been done before, but since I couldn't readily find the information (because I was searching for IBM 55SX error codes and CMOS problems), I am presenting my own version, and then some observations to help you do a cleaner, safer job.

Step 1: The Discovery, and Intro to Problems

I found this gem sitting out at the curb about 6 months ago. Being the good junk collector that I am, I grabbed this, and some other stuff and stuck it in my van.

I've been riding this around in the van, in Florida, until last week. I had to finally clean it out (there may be an instructable on that too) because a water leak was growing a mold colony in the carpet.

Anyway , I grabbed this machine out and stuck it in the garage. After a few days there, I had some free time and decided to see if it even powered up.

To my surprise, it did, so I grabbed a monitor, mouse and keyboard and hooked them up.
I was getting errors 161 and 162, and then a crude picture basically telling me something was not OK.

I went online and found out that the codes are:

161 System Options Not Set-(Run SETUP); Dead battery
162 System Options Not Set-(Run SETUP);CMOS checksum/configuration error

I never had an IBM back in the day. I was a commodore guy, so this was my first trip down PS2 memory lane.

I learned that I needed a reference disk, which I downloaded at:

IBM PS/2 Model 55SX

There are also several other places to get this disk.

After getting the disk running, an IBM program took me through some steps, then asked to restart the system.
After the restart, the problem errors repeated. I left the computer on for a couple of hours (hoping to get a charge into the CMOS battery), then tried it again with the same results.

I did more online reading, and discovered that the CMOS battery was not only dead, but obsolete as well. They offer an updated replacement from the company that made the originals, but it is not guaranteed to work.

Link updated 10/4/2012

Dead link:

New link:

Replacing the DS 1287

After reading this, I decided to look around to see if I could find which pins connected to the battery.
The pinout guides are all pretty bad, and even the best ones that I could find didn't have the battery input terminals labeled.

This leads me to my next course of action.

Step 2: Preparing to Hack Up the Dallas DS 1287

I read an online text post from back in the 90's about someone who "just cut the top off and replaced the battery".

This sounded like the way to go, so I pulled the chip out (bending some pins too, darn it) and got to work.

Step 3: Hacking Up the DS 1287

First I got a small block of wood, a carpet knife with a very sharp blade, and a pair of needle-nosed vise-grips.

I started carving around the top edge of the case, just a little down from the top, when WHAMMO, I cut the living squack out of myself. The top of my middle finger on the left had stopped the blade quite well, once it hit something solid under the skin.

Not thrilled about this, I bandaged up my finger and kept going.

After a bit more work I noticed that a layer was coming off, so I used a screwdriver to remove that layer.

Once that layer was the chip case looked like Picture #4.

I was doing more carving and clamping with the vise-grips when a piece chipped off, revealing that the top part was mostly solid.

I was already doubting the story of simply cutting off the top, now more drastic measures were needed.

I took the chip out into the garage, and with a hammer and straight tip screwdriver, proceeded to beat the two halves of the chip apart.

Step 4: The Aftermath

Once I had it coming apart, I tried to be careful to not snap the bottom chip, or hurt the crystal that I assumed was in the top part.

I succeeded in getting the battery out, but at the same time I broke off (and chipped) the part that had the crystal in it.

Now it was time to try and get it back together again.

Step 5: Re-assembling the Parts

The reason that you can't find the battery tabs (or the crystal tabs for that matter) is because they bend those tabs up to connect them to the items on top of the chip.

The battery was installed positive side down, so I left the tab for the positive there.

I took the part with the crystal and put a dab of silicone sealant on it and taped it in place with the pins touching.

I soldered the pins back together that went to the crystal.

Then I used the other pieces to find out which pin was the negative battery pin.

From there, I temporarily tack soldered a 3V lithium button cell to the positive tab.

Then I soldered a wire to the negative tab and tacked it to the negative side of the battery.

I wasn't worried about neat at this point, I was just wondering if it still worked after the beating and multiple pin bends that it endured.

Step 6: Into the Belly of the Beast

I carefully plugged the chip back into the socket, noting that the dot on the now destroyed case lined up with the single pin on one side (glad I took those pictures).

Step 7: Reward !

It worked !! I popped in the reference disk again, and this time I got to go through a lot of options to pick and save settings, disks, etc.

After the reboot, the machine loaded Windows 3.1

It was a pretty plain install, and I played with it for about 30 minutes and then shut it down and went to bed.

After doing this, I see plenty of ways to make it safer, less messy, and better looking.

In the last picture of this step, I have indicated the locations of the positive and negative battery terminals inside the top part of the chip.

If I get another chance, I would try to use a drill and gently drill into these areas (fairly close to the top from the side view) to disconnect the old battery, and then solder a wire in to connect to the new one.

You can buy a lithium battery holder, and run the wires from the chip to that.

This would make a much cleaner and faster project.

Step 8: No Rest for the Tenacious

The next day I hooked up this machine to revel in my success, only to find that it wouldn't start up.

Nothing. Zip.

Back to the internet, I found out that the power supply should start up, whether it was connected to the motherboard or not. I disconnected the power supply, and it didn't start up.

The couple of hours must have been too much for the dusty old brick.

I did a brief online search for another one, but these are hard to find, and probably close to dying anyway.

So I did the next best thing.....

Step 9: Bonus Steps!

I pulled the top off of the old power supply to look for a blown fuse, but the fuse was fine.

I did more research on the internet, and put together the following information about my IBM power supply, and the older 200 Watt ATX power supply that I was willing to use:

Standard (200W ATX) Power Supply plugs

PC Power supply connectors

IBM 55sx Pinout From Motherboard

Where I got the motherboard pinout for the 55SX

So, from old ATX to IBM, pins are as follows:
(RED is +5V on the HD connectors from the ATX PS, just in case)

Standard (200W ATX)------TO-------IBM P7

Orange--------------------------White PWGD (pin 1)
Red --------------------------(+5 volts or connector key) not used
BLK------------------------------All BLK


BLK------------------------------All BLK
White--------------------------Yellow (-5V)
Red----------------------------All red +5V

Standard (200W ATX)------TO-------IBM P14


RED----------------------------all 3 are +5V

With this information, I put together a Franken-Cable, and then got it connected up.

Step 10: Back in Business!

I flicked the switch on and....

It booted up !

Here are a few screenshots from the unmodified computer..

I hope this helps someone get information off an old computer that they really need, or maybe just gets someone to go out into their garage or storage unit (or van) and grab an old piece of equipment and give it a little more life !

In the next step (completed about 15 days later) I get the Power Supply into a more permanent position.

I am also planning to neaten up the CMOS battery install, which I will add to the end of this Instructable once it is finished.

Step 11: Revisiting the Power Supply

Sure, the power supply works, but it won't fit in the case correctly, and the fan and power ports through the case are on the opposite sides.. (note the power cord coming in through the fan hole in the case in the first picture!)

Getting a little free time, I decided to transplant the newer power supply circuits into the older power supply case.
This solves a lot of problems, like the on/off switch being back to the way it originally worked, the fan and power port alignment, and just having the power supply fastened correctly inside the case. Also, this temporary setup won't allow you to put the top back on the computer, unless you want to take it back off again to turn it on!

We start with the old case (missing the power switch) in picture two.

Step 12: Taking the Old Power Supply Apart

The old power supply had a few screws that held two interlocking panels together.
You remove the top screws, and the two by the power switch, and the top panel folds away from the case and unhooks.

As seen in picture two, they used a special type of screw on this Power Supply. It has a little metal pin in the center of a phillips head screw. I just used a tough small straight tip to either snap out the pin, or get a grip on two sides of the phillips slot and remove it.

Remove the screws from the bottom panel, it also folds away from the case, and you will have three parts, like in the first picture below.

The third picture shows the main Power Supply case with the circuit board removed. (4 screws)

The last picture shows the dirty insides of the old Power Supply.

Step 13: Taking the Newer Power Supply Apart

The first picture shows the insides of the newer Power Supply.
Note that the board appears to be smaller.

In the second picture, you can see that they wired the power ports through the case of the power supply, making it difficult to remove them once installed.

That is, unless you have a nice set of metal snips to free them from the case.
(See third picture)

Step 14: The Transplant Begins

As you can see in the first picture, only one screw connects the new power board to the old case...

So, in pictures two and three, I cut some metal from the now empty Power Supply case, using existing threaded screw holes, and trimmed them to make two additional supports.
Pictures two and three show the same bracket from rough to finished.

In the fourth picture, I have three sides fastened to the case.

I wasn't really worried about the board touching the metal bottom of the case because it was a pretty safe distance away, but just to make sure something crazy didn't happen, I reused the cardboard divider from the new Power Supply, then used some motherboard standoffs on the last corner to make sure it would never ground out (picture 5).

In picture six, you can see I had a lot of wires to deal with. There was the extra power out port, a really long wire for the power switch, and way more wires for power than the original Power Supply had.

I zip tied the power switch button wires in a bundle, then zipped them to the side of the case (picture 6).

Luckily, the side that the power wires came out of had a long smooth slot that connected the hole for the original wires, so I just lined the wires up in the slot and gently zip tied the inside and outside to keep the wires from moving too much.

The last picture shows the supply ready for reassembly. The old fan is connected, and the additional power out socket is zipped in place and the rear wires are taped.

Step 15: The Transplant Is Complete!

The transplant is a success!

The first picture shows the supply installed in the machine (note the black plastic support for the riser card).

I have a few extra molex connectors now, but since both the drive and the floppy are powered from the ribbon cable, I'm not sure what to use them for.

Everything connected up great, and there wasn't too much strain on any of the connections or wires.

The last picture shows the rear of the machine, with everything lining up perfectly.

I'll be cleaning up the CMOS install when I get some time, and then I'll append that to the end of this Instructable.

If anyone has any parts they would like to donate (or sell cheap!) for my Franken-Machine, here is a short list of what I'm looking for (keep in mind that this is an MCA board):

4MB or 8MB sticks of ram
ram expansion card
80387sx math coprocessor
video card
sound card
lan card



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    Welcome to 2017!

    Unlike some things on the internet, old instructables are still just as useful now as they were when they were written!

    I check in now and then to update things that may not be clear, and to reply to comments.

    I still haven't gotten the clock fancied up like I wanted, but soon... soooooon!

    Not sure what model (or brand) it is, but I have an old computer (probably) running Windows 3.1 (previously DOS), but it goes snap, crackle, pop (Rice Krispies!) when I turn it on... I'll probably find some time to work on it and (probably, but maybe not) post any updates...

    Oh, and the bright blue sparks that came out came from the power supply... it kept running, but I unplugged it immediately (not thinking, or caring about the hard drive) to avoid the risk of fire and completely destroying the entire machine. (A repairable hard drive is better than a non recoverable hard drive, right? Oh, wait, I read something about a spaceship that landed on Earth but with trial and error, removed the platters from a hard drive, placed it in a new drive, and figured out the firmware and got almost all of the data off of it, even though the rest of the drive was melted... I don't remember the link, but Google is your friend. Look it up sometime. It's a great article. Oh, and look up the article, not Google. Well, you can look up Google if you want, I don't care, but remember to look up the article.)

    Ha! Nice story! I hope you get a different power supply, and chuck the sparking one out ASAP!

    I hope you didn't hurt your arm pulling it out! It's a monster...
    Maybe you can get it going and have some fun!

    wow that Fing nice job that is pro finish yo

    Thanks !

    I put a lot of work into that baby, but I'm still waiting for time to get the RTC back up and running in a solid package !


    I have that same computer my uncle gave it to me

    LAN card? like ethernet? also upgradeable ram! see if you can get the max ram the motherboard will accept and install XP.