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Vintage Computers Any vintage computer systems, calculators, video games etc., but with an emphasis on 1980s and earlier equipment.

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Old 10th Sep 2018, 8:19 pm   #1
Ontopoftheworld
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Default IBM PS/2 seems to have got stuck!

Hi

Could some one give me a clue regarding what has happened to my dear old computer. It was working yesterday. It crashed (because I moved it while it was on), and I went to turn it back on. However, the light on the harddisk turns on momentarily, and the power fan spins momentarily and then stops, and nothing else happens, nothing appears on the monitor. There is no light on the motherboard, presumably there is not one, so I cannot see if it's a problem to do with the motherboard.

Any suggestions, gratefully accepted!

thanks
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Old 10th Sep 2018, 8:42 pm   #2
Dave Moll
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Default Re: IBM PS/2 seems to have got stuck!

I hope I'm wrong, but it sounds as though it has literally crashed - as in crashed the heads into the surface of the hard disc. If so, the only solution is probably to replace the hard disc.

To prove that the rest of the computer is OK, is it possible to try starting it up from a floppy disc?
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Old 10th Sep 2018, 8:44 pm   #3
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Default Re: IBM PS/2 seems to have got stuck!

Any beeps?
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Old 10th Sep 2018, 9:52 pm   #4
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Default Re: IBM PS/2 seems to have got stuck!

No beeps. I've tried booting without the HD connected but it doesn't make a difference.
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Old 11th Sep 2018, 1:30 am   #5
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Default Re: IBM PS/2 seems to have got stuck!

A PS/2 of any model should boot regardless of the state of the HD, so you can get to the setup floppy stage. At worst you should be able to boot into ROM BASIC. Which model PS/2 is it?

I think this looks like a power supply problem at first guess. Either that or the PSU is detecting a problem and shutting it down. So somewhat contradicting my first paragraph, I'd pull all the cards except the video adapter (if it's a separate card) and see if you get anything.
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Old 11th Sep 2018, 5:25 am   #6
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Default Re: IBM PS/2 seems to have got stuck!

It's the 286 version. That's a good idea about the cards. I'll try that this evening. I think I'll have to dismantle it all and give it all a clean too. Could be a long job!
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Old 11th Sep 2018, 8:49 am   #7
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Default Re: IBM PS/2 seems to have got stuck!

Another vote for the PSU. Electrolytics in SMPS's are notorious for poor start-up, especially if the machine has been left on for long periods and then is asked to do a cold start.
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Old 11th Sep 2018, 11:38 am   #8
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Default Re: IBM PS/2 seems to have got stuck!

As a quick try put the hair dryer over the power supply caps if only to prove a point.
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Old 11th Sep 2018, 9:54 pm   #9
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Default Re: IBM PS/2 seems to have got stuck!

Tried a hairdryer on the power points. When I turned it on, for a tantalizing moment I could hear the hard drive whirl, but only for a second and then it was quiet again.

I'll need to try dismantling, cleaning etc next.

I think it's either the PSU, or the mobo.

It would great to get another PSU and plug it in, just to rule out that. However I don't suppose that's an option with these IBM PS/2's. I'm beginning to realise the problem owning one of these computers!
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Old 12th Sep 2018, 1:20 am   #10
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Default Re: IBM PS/2 seems to have got stuck!

There were a number of 286 versions. They are all called "Model X", for instance I've got a Model 60 which is one of the 286 models.

The PS/2 PSUs were like IBM stuff in general well built and I believe contained various protective circuitry to shut them down to prevent further damage, which may be what is happening here. I wouldn't be entirely surprised if this is just a loose connection due to the move causing the PSU to not detect something properly. As such the magic of taking something to bits and putting it back together without doing anything else may work as all the connectors will be reseated.
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Old 12th Sep 2018, 8:15 pm   #11
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Default Re: IBM PS/2 seems to have got stuck!

This evening the computer started booting up for 10 seconds and then died again. I'll take it apart, give things a clean and put it back together again on the weekend and hope for the best. Let's face it, that's why we love these old computers!
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Old 15th Sep 2018, 3:17 pm   #12
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Default Re: IBM PS/2 seems to have got stuck!

Took it all apart and cleaned everything. Tried just hooking the PSU to the motherboard, switched on, the fan started on the PSU, there a little whirling noise and then nothing. So same problem as when everything is connected. so this problem is either the motherboard or the PSU.

Could someone tell me if it's normal for a PSU fan to turn for a second or two and then stop? It does that even when not connected. If it's not normal then the problem must be the PSU. If it is normal then it's the motherboard that is faulty.

Thanks
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Old 15th Sep 2018, 3:40 pm   #13
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Default Re: IBM PS/2 seems to have got stuck!

Quote:
Originally Posted by Ontopoftheworld View Post
If it is normal then it's the motherboard that is faulty.
There may, of course, still be a problem with the PSU that doesn't affect the fan, as the PSU (when working) produces a number of different outputs (including the main 5V and 12V ones) to power different parts of the computer.
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Old 15th Sep 2018, 6:31 pm   #14
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Default Re: IBM PS/2 seems to have got stuck!

Last week I dug out my first 'Proper' computer - an IBM PS1 with a 486 25sx cpu and an 85Mb hdd. It's been in my shed, uuntouched since about 1996 and refused to start up. After trying everything I could think of, to no avail, I replaced tbe CMOS battery and everything came back up! I was delighted to be able to once again experience the joys of Windows 3.1 and DOS 6.0.
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Old 15th Sep 2018, 11:00 pm   #15
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Arrow Re: IBM PS/2 seems to have got stuck!

In my experience, your test results in post #12 are highly suggestive that the PSU is the primary suspect.
It's been a long time since I was professionally employed in the maintenance of PS/2 PCs, but if the voltage O/Ps and control lines are standard, it might be worth temporarily hooking up an out-board PSU from a different PC (e.g. not a PSU from a PS/2) for a test.

Al.
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Old 16th Sep 2018, 3:19 am   #16
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Default Re: IBM PS/2 seems to have got stuck!

I also strongly suspect the PSU. Wouldn't be surprised if its an old capacitor(s) problem.

I am pretty much certain though that you need a PS/2 PSU for swapping. It's not the same as either the AT or ATX PSU.
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Old 16th Sep 2018, 3:09 pm   #17
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Default Re: IBM PS/2 seems to have got stuck!

It sounds like the PSU could be crowbarring as well. Best way to isolate is divide and conquer. Separate the mobo and measure the resistance of the + - 5V and + - 12V pins to ground. There shoud be some resistance. I had a Compaq mobo with the same symptoms and it was found to be a shorted bypass tantalum on the mobo.

As others have suggested it may be time for a capacitor makeover in the PSU.
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Old 16th Sep 2018, 10:12 pm   #18
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Default Re: IBM PS/2 seems to have got stuck!

Thanks for your suggestions. The sway of opinion definitely seems to be pointing at the PSU being the problem. I don't have any knowledge of electronics so I don't think I'll be able to even start re-capping the PSU, or adapting another type of PSU. I think I'm going to have to wait to replace it.
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Old 17th Sep 2018, 12:19 pm   #19
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Default Re: IBM PS/2 seems to have got stuck!

It would help to know the model. There are a handful of PS/2 power supplies on eBay - for example there's one for a model 30 (which was a 286) in Italy.

If you have the IBM FRU code from the supply, you should be able to find out what your options are.
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Old 17th Sep 2018, 8:00 pm   #20
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Default Re: IBM PS/2 seems to have got stuck!

Yes my PSU is FRU 27F4166 which is 90W, and my IBM PS/2 is a 8530.

Yesterday I bought a PSU 61X8574 on ebay which is advertised for the PS/2 8530 and is 70W. So I'm not sure I've bought the right one, maybe it doesn't matter.

Hopefully it will still work!
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