Vivien wrote:

Hi!

I have come across a IBM PS/2 65 SX computer that has been sitting in storage since around 2003. That particular model was announced in 1990 so the computer is possibly as much as 28 years old now. I'm aware that electronics degrade with age and I've heard stories about old equipment developing faults - mostly capacitor problems. So what I'm wondering is how safe is it to plug it in and turn it on?

IBM PS/2 (Model 65 SX) - Technical specifications

Not only capacitors go bad but there is also a problem of insects that may be living inside, i would perform a full check on the inside of the computer. including the capacitors.

I would definitely look inside and check for mechanical issues (loose components, half-unplugged connectors, etc.) but other than that, it's pretty safe to turn it on. Contrary to popular opinion, I haven't found capacitors to be a major problem at all - certainly not on pre-2000 computers which didn't have switching regulators on the motherboard. Really old power supplies all seem to be fine as well. There were some crappy power supplies produced from the ATX era until now, but all AT supplies I've encountered have worked perfectly and still do. And if you're talking about old IBM stuff ... I'm pretty sure you'll be fine.

I have never owned an IBM PS/2 with a bad power supply yet, so yes I would give it a try.

In contrary, the earlier IBM PC AT and many Taiwanese clones do develop power supply problems over the years. Still, I have never seen one catch fire, but I have heard loud ‘bangs’ and seen sparks and smoke coming from old power supplies. Especially tantalum capcitors (found on some motherboards, graphics card, floppy drives etc.) can explode (it’s not dangerous if you keep your distance).

My advice is to first visually inspect the computer for any obvious problems, then connect the power supply to a power strip, turn on the computer, keep some distance, turn on the power strip and let the computer burn in for an hour or so (preferably outside).

uxbill on youtube calls it a smoke test 😀
and people say old computers are boring!

If something goes bang and smokes, it's probably a power supply capacitor that can be replaced.

Just check to see if they are bulging, like this:

If the tops are flat then the only way to find out for sure if they're good is to turn it on. A sign of failure is finicky power problems; i.e. the machine has difficulty turning on and staying on etc. As others have said, yes, check for loose or unplugged cables - and it's probably also a good idea to reseat all the cables that are already plugged in. Any other obvious damage would be a warning sign.

Another big killer can be the little coin batteries; they can leak over time and damage things.

dosgamer wrote:

Contrary to popular opinion, I haven't found capacitors to be a major problem at all - certainly not on pre-2000 computers which didn't have switching regulators on the motherboard.

One of my Apple IIgs computers had a filter capacitor in the power supply go out with the lovely smell of burning paper. Tantalum capacitors can also pop. It's a valid concern.

Well the computer I have that had the highest capacitor failure is acually my oldest PC :
it's an XT clone from 1988. The HDD had bad tantalum caps preventing the computer from starting and the PSU had bad caps making the whole computer totally unstable. Once I replaced all of them the computer was fine