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IBM PS/1 (model 2121) won't boot up anymore

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SonataFanatica

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Jan 29, 2016
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Hello there!

I've been searching the web for answers to some problems I have with my IBM PS/1 (model 2121).
(In fact, I have two of them at home, one of which has a monochrome monitor and the other a color monitor.)

Now one of the two computers has always worked really well. Everything worked perfectly apart from the fact that I got the errors 161 and 163 when booting up, but I take it those are only because of the empty CMOS battery.
Pressing F1 always bootet the PC up just as well.

Yesterday, I wanted to install MS-DOS on a new empty hard drive. The problem was that when I changed the boot sequence in order to boot from floppy disks, it only worked when I had the original hard drive connected.
So whenever I connected a new hard drive to the computer and THEN booted it up again, the computer would always boot from ROM and not load the floppy first.

So I booted up the computer with the original hard drive, set the machine to boot the floppy drive first, restarted the computer with my original MS-DOS setup disk (1 of 3) in the floppy drive, waited until all loading was done (the MS-DOS installation program said "please press RETURN in order to install MS-DOS") and then WHILE the computer was running, I unplugged the original hard drive from the power and data cables and plugged those cables into the new, empty hard drive.

While I was in the middle of plugging the new one in, the screen went blank.
So I shut down the computer and turned it back on.

Now the thing doesn't start anymore.
I don't even get into the POST.
I turn it on and the screen stays black. The only things running seem to be the monitor and the computer's fan.
No hard drive (neither the original one, nor the new one) even powers up.

Did I break it completely? I know it was a stupid thing to do, but I really thought it would work. And even if not, I didn't think I'd break the computer that way...

Does anybody know anything I could do?
I'm absolutely crushed and couldn't sleep last night because of it all...

Thank you in advance for any replies!

PS: Of course, I also tried booting up the other IBM PS/1 I have, but it turns out that one doesn't boot up either. It also doesn't get to the POST.
I tried both monitors, but to no avail.
 
Although I do not know this system, there are a few basics you can try. First, if there is no power at all check AC cables, extension AC cables and fuses in the mains plugs. (its possible one of the fuses was a low amperage and didn not like th epower spike). There might be an internal fuse - check that too. If you have a multi meter you can check for correct voltage at the power supply output to the main board/planar. If all looks good there then remove any extra cards, the hard drive and floppy drive(s) along with cables, mouse and keyboard and try turning on the unit with the minimum ammount of devices connected. If it turns on, reintroduce the devices one at a time (whilst the PC is turned off) untill you find the part thats giving the problem. With everything disconnected, and the power supply is definately working...then you might be in trouble.
 
Thanks for your reply!
The thing does get power. The power fan works too.
When it comes to "disassembling" the thing... well... that's a bit of a problem with the PS/1 model. There's not much you can remove. I can unplug the floppy drive, the hard drive, the extension card which holds the ethernet card, the printer connection, and the power fan. But that's it.

When everything I mentioned is disconnected (apart from the fan, of course), it's still the same problem. It doesn't even boot up to the "beep"...
 
Somebody just told me that I probably fried the IDE controller by "hotswapping" the hard disks. Now if that's true, I don't know why the other PS/1 I have doesn't boot up either. Do you think that exchanging the CMOS battery could help in any way?
 
Does the IDE drive motor spin up? Not familiar with PS/1 but that is usually driven straight from power supply.
Also you say fan spins up. Is that external to power supply? Is it a DC fan? (Would be smaller and colored wires)

Larry G
 
You mean the motor of the hard drive? No, it doesn't.
The fan does spin up, yes. It's a small one at the rear end of the mainboard and is connected with black and red wires.
 
So that should mean your DC supply is working for the fan. It should be the same DC supply that gives power to the hard drive. Do you have a voltmeter? The 4 wire power connector for your hard drive should have red and yellow wires. The yellow should have 12V for the motor to run and red is 5V for the controller electronics. Just measure to black wires which are ground.
 
So I've been studying that model online and it sure is an odd duck. I was watching vwestlife's video so maybe he'll chime in here. I'm pretty sure that small chassis fan is 5V. Should be a sticker rating on it. Essentially 32v comes from the CRT display and feeds the vertical power module which feeds 5v and 12v out. The power connector on the motherboard that goes to the ide drive has a red wire and a (white?) wire. I'm guessing the red is 5v and the white is 12v. If you don't have a meter, buy one, they're cheap or borrow one. If the 5v is present but the 12v is gone, I bet you popped a fuse in that vertical module or somewhere nearby. A fuse can just be a 0 ohm SMD too. I think I saw some in the video when it peered down into the module. Good luck.

Larry G
 
Okay, just a quick update.

I haven't checked the voltage yet (due to my lack of a voltmeter), but as I've said before: I have two IBM PS/1 at home. Both are model 2121 and should have the same specs.
I've figured out that the other model (the one I haven't messed with) does at least power up the hard drive, too. So I took the floppy drive & hard drive of the "broken" one and here's the result:


So, as you can hear: at least the hard drive gets enough power now to get a good spin at the start. However, I still can't even get to the POST.

(Remember: this is a different IBM PS/1 which I hadn't even opened before, so I don't know why this one doesn't boot correctly.)

A friend told me that this may be the fault of the empty CMOS battery. So now I've bought new ones and put them in but there's no change.
 
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I would advise trying to get the ps/1 that initially worked running again. You know it worked and you know how it failed. I doubt plugging in a drive while active actually damaged the drive as far as hardware. It could damage the software on it.
I have worked with many removable ide hard drives in bays and accidentally plugged them in/out while running and I don't remember damaging a drive. In fact, reseating an an inoperable drive usually got them to boot again. You need to find out why the drive doesn't spin up. You could try swapping out the vertical power module from the other one. Once you have a functioning unit, You can start doing side by side comparisons to fix the 2nd one. If the power module is bad, you will need a meter to measure for an open fuseable resistor. If you want to work in this vintage world, purchase a multimeter.
 
retrogear said:
I have worked with many removable ide hard drives in bays and accidentally plugged them in/out while running and I don't remember damaging a drive. In fact, reseating an an inoperable drive usually got them to boot again.
Click to expand...

I can agree here. Even though IDE/ATA isn't technically a hot-pluggable bus, I've never seen a peripheral or controller die from doing it. The most you should expect is the machine to reboot, hang or crash when the device is removed or re-attached.
 
You should also expect to lose all data on the drive. A friend of mine accidentally pulled out a 60 GB NTFS-formatted drive from its removable rack while the machine was still running. After that the drive appeared to be blank (as in not partitioned) in Windows and he had to run some data recovery software on the drive to recover his stuff.
 
retrogear said:
I would advise trying to get the ps/1 that initially worked running again. You know it worked and you know how it failed.
Click to expand...
Yeah, but... that's the one that doesn't power up the hard drive anymore...

retrogear said:
I doubt plugging in a drive while active actually damaged the drive as far as hardware. It could damage the software on it.
Click to expand...
And that's exactly why I didn't think it was such a dumb thing to do, you know? I took into account that I'd probably ruin the ("new", empty) hard drive, that's why I used one which isn't important to me.

retrogear said:
You could try swapping out the vertical power module from the other one.
Click to expand...
I just made a video. So the "card" that's plugged onto the motherboard vertically is the power module (the one that's to be seen at the beginning of the following video)? :


This is the unit I messed around with. So you can see exactly what happens when I power it up - without floppy and hard drive and with them.


I've just exchanged that vertical module but there's no change. The hard drive still doesn't get a spin when turning the power on...
So the problem must be somewhere else...


Do you think something like this could be of use for me in order to get to the bottom of the problem? : eBay link
 
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Looking at your video, the power connector to the hard drive is not standard? Yours is alternating grounds where standard power connector is grounds on the center pins? Is your "new" drive a standard ide? Power is wrong !!!

Larry G
 
I'm sorry but I don't really know what you mean... what can I do about that?
As far as I know it's always been in there and everything worked until recently (until I messed up, as I've written in the opening post)...
 
Maybe the color coding on the wires doesn't matter but on a standard ide hard drive the 4 pin power connector pins 2 and 3 are ground (black wires) but on yours I saw black wires on pins 1 and 3. It just startled me.
It just doesn't look right. I never heard of a different power plug arrangement so not sure. Wish you had a meter. I don't think the diagnostic card will function for your ps1. Those are based on standard pc bios computers.
Since your failure coincided with plugging in the "new" hard drive, that would explain why the system bombed at that point. In fact, it might have fried your new hard drive, hope not. Hopefully someone else on this forum can
confirm whether the model 2121 used "standard" ide drives. I would have thought so.
 
Ah okay.

Yeah, I thought about the new drive being fried, too. But I haven't tried to use it since. I have the old drive in there again.
 
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