Based on this picture of the motherboard, is my PS/2 Model 25 safe to turn on?

OmegaWolf747

I was pleasantly surprised to find the interior so clean when I opened it up. It looks like it’s been well cared for over the years. However, I’m no electronics expert. Could someone here tell me if it looks safe to power up based on this photo of the motherboard? I can provide close-ups of the components if necessary.

Deepest thanks. 🙏🏻

broknsymetry

The main components to worry about would be electrolytic capacitors. I don not see any on the motherboard, but you should check the power supply for any that are swollen or leaking.

real_aurgathor

I see at least 6 caps that look like tantalum electrolytics – they have their own failure modes, but not likely to apply here.

There are 2 major failure mode for aluminium electrolytics:

degradation when used as a filter in switching supplies – very common in certain years
age and heat related dry-out in old (mostly 50+ years) radios and such, but that shouldn’t be the case here.

Turn-on incidents normally happen in case of #2 above. (or when a cap was installed with wrong polarity, but that shouldn’t be the case here)

GrumpyCanadian

I will also agree with the two previous comments. It would be a very good idea to remove the cover on the power supply to make sure that it is clean and that there are no bulging/leaking capacitors. However, it is important to do this before plugging in, unless you are experienced in such service, as some of the components can hold a lethal charge for a time, even after unplugging again. Checking the power supply is even more important if the machine was used in a household with at least one moderate smoker, as that tends to encourage additional build-up that is more challenging to remove.

If unsure, include pictures, and someone will likely be able to offer additional commentary. Also inspect any other fans for built-up dirt.

Capacitors like C14 and C93 (and others like them) on the motherboard do look like tantalum capacitors. These can sometimes fail after long periods without being used. Usually, it is still relatively safe to test the machine if no other problems are found, as they won’t cause permanent damage if they do fail. If you hear a loud pop and see smoke, they will need to be replaced.

Astyanax

I have to disagree with opening the power supply. Typically that’s not a “user-serviceable part” and by doing so you may be creating a hazard that may never have been there before opening it.

I’d just plug it in and fly it but do it in a garage or outside just to be safe.

ElQuintron

Moved to PC Hardware, better forum/tag

GeekGirl1

Astyanax I’d just plug it in and fly it but do it in a garage or outside just to be safe.

I would agree. I once had an electrolytic cap fail when I had a PC power supply opened up. Cool - it left a trail of dielectric material as at launched out of the supply and onto my desk.

That was after I heard a sharp “bang” - What was that? The capacitor. Oops.

real_aurgathor

Astyanax I have to disagree with opening the power supply. Typically that’s not a “user-serviceable part” and by doing so you may be creating a hazard that may never have been there before opening it.

That depends on the “user” and the type of “service”.

Opening the power supply should not create any additional hazard, and the majority of PSs are not too difficult to open.

I usually remove them and open their cover once in a while, although normally for un-dusting since they can accumulate enough dust to possibly cause problems. Once they’re open and reasonably clean, checking for pregnant or leaky caps should be very trivial.

Of course in the OPs case, there’s probably not much dust in the PS as long as the mobo’s picture was taken without previous cleaning.

GeekGirl1

I’m seeing 1987 date codes on some of the chips.

Where’s the CPU and heat sink? For those that may not have been around in 1987, the CPU is an Intel 8086. No heat sink was used.

If this was a newer design, a missing heat sink is a big deal. You’d get about 30 S out of it until the CPU overheated and shut down.

Here’s the mobo with the layout and better pictures: IBM PS/2 MODEL 25-286 (8525)

The CPU is obscured in the OP’s picture. I’m still with the “just plug it in” crowd.

egeezer

GeekGirl1 . I’m still with the “just plug it in” crowd.

“Here, hold my beer and watch this!” 😄

GrumpyCanadian

GeekGirl1 I once had an electrolytic cap fail when I had a PC power supply opened up. Cool - it left a trail of dielectric material as at launched out of the supply and onto my desk.

Nobody said to plug it in while the power supply cover is off! My suggestion was to take a look under the hood before ever plugging it in, just for cleaning purposes, and to make sure that nothing is obviously about to blow up, then carefully replace the cover before plugging in. Old IBM machines weren’t usually machines where they skimped on components, but especially with bean-counter specials for power supplies, those precious bang moments can take nearly everything else with them.

GeekGirl1

GrumpyCanadian Sorry for the misunderstanding. Thanks for the clarification.

GrumpyCanadian

GeekGirl1 Actually, you were right to question unclear or questionable advice. That idea may have been clear to people who are more familiar with the risks, but not necessarily everyone. I didn’t explicitly write that above, and it’s better to be clear than invite unnecessary risk.

There’s a reason power supplies have warning stickers on them. That is why I suggested to have a look before ever plugging it in, under the assumption that it hasn’t been powered in months or years. For any beginner, power should never be applied unless the cover is securely fastened in place. The cover should also not be removed after it has been plugged in, as the components will likely retain some (potentially lethal) charge.

The goal is only to clean out any significant dirt and check on the components before power is applied, not invite unnecessary risk.

Somewhat-Reticent

And even then, avoid conductive contact.

egeezer

GeekGirl1 I once had an electrolytic cap fail when I had a PC power supply opened up. Cool - it left a trail of dielectric material as at launched

I had a lab partner in EE who wired an aluminum cased Zener diode backwards in a project. It sounded like a firecracker when it exploded, mini-shrapnel flew and a piece of it bounced off my glasses. After the shock wore off, the poor guy received a round of applause from everybody but the GA who was overseeing the lab.

GeekGirl1

egeezer mini-shrapnel flew and a piece of it bounced off my glasses.

I can’t understate the importance of wearing safety glasses. I wear glasses and if anything flew towards my face when that electrolytic cap exploded, my glasses protected me.

You wouldn’t think of this for anything that’s just electronics, but any time you’re working on something that has even a slight chance of hazard - protect yourself.

I also wear hearing protection when working with noisy power tools, e.g. a table saw. Also, when running my lawn mower. Because of doing this for most of my life, my hearing is far better than my peers.

real_aurgathor

GeekGirl1

GeekGirl1 , the CPU is an Intel 8086.

The CPU is actually a 80286, but the 386 was already available in expensive models..

egeezer

GeekGirl1 I also wear hearing protection when working with noisy power tools,

I was a tool and die mechanic in my early days in an extrenely noisy facility full of punch presses that left me with tinnitus.

Now I wear noise canceling bluetooth earbuds for yard or garden work. Besides, I can listen to music when mowing or blowing off the sidewalks and driveway.

OmegaWolf747

real_aurgathor There was no previous cleaning. It was that clean when I opened it.

I’m not really too keen to open up the PSU.