The question is what current will be flowing? It could be +5V at 1mA or even 10uA... The +5V itself doesn't tell if there is a charge current flowing. All diodes have leakage. Do you know the type of battery that was connected before?

Oh right !! I totally forgot about this.

I shorted the ""+5V"" with GND using a 6.8K resistor that was laying around and it dropped to 0.02V. I guess there's nothing to worry about then.

Here's the original battery

Glad that's cleared up. The battery also says "Do Not Recharge", btw.

Why didn't I see that before 🤦‍♂️

Yup, glad this was cleared up. You could even get a new lithium battery, e.g. by SAFT with 3.6V and simply attach that.

I can't definitively say they don't exist, but I have never once in 25 years of doing this seen a motherboard that uses a rechargeable EXTERNAL battery

Well, here's the before/after look 😀

I've simply placed the new CR2032 battery holder in place of the old lithium battery. I even took the old battery's connector and velcro attach. So now the computer "future proof" 😀
Actually I may rename this topic "ICL 286 restoration" or something similar 😁

Today I got XTIDE working in the computer 😀

This allowed me to install any HDD i wanted, so I chose a ~260MB hdd from seagate.
Then I installed MS-DOS 6.22 and mTCP.
I also installed a Sound blaster 16 pnp and Unisound to properly configure it.

Finally I ran some games and I even finished Day of the tentacle on the system 😀

Also, the back of the computer was quite rusty, so I cleaned it the best I could using iron wool. It still looks dull, but it's not rusty anymore (some screws are though)

I also fully cleaned the case and the fan. There are some marks here and there and bits of rust in the top cover, but everything else is good.
Only the front is still quite yellowed ...

Also here are pictures of the motherboard when I fully disassembled the computer for the curious people 😀

I also tried some UMB drivers made for the C&T neat chipset, but unfortunately none of them worked ... I guess the BIOS (made by phoenix and sold by Acer) simply won't let me use that ... Oh well I can live with that.

Nice PC and good work! What was wrong with the HDD? Maybe you could find some drivers on it..?

Well the old HDD is totally stuck. When I try to move its platters, it's really hard so the hdd can't start. It doesn't seem to be a horrible headcrash that's causing this problem. I think it's just the motor that's toasted (probably bad lubricant)

I tried to free it by rotating it manually for several minutes but it only slightly improved ... If you have any ideas ...

Well some icing on the cake : memory optimization on a 286 machine 😀

I now have 622KB free with every drivers loaded (mouse, keyboard, network, smartdrive ...). Even Himem.sys is loaded high X).
Only, I had to upgrade it to 2.5MB of RAM to reach that, otherwise HIMEM.SYS wouldn't load at all because it couldn't find XMS memory.

All of this have been achieved thanks to UMBDRVR ! A very, very good "universal" chipset driver for memory management from 1992, similar to "umbpci", but for older stuff.

Okay so today something terrible happened ...

I was using the computer as usual, but suddently it stopped ... And a purple smoke came out of the PSU 😮

I stopped it and put it oustide as I don't want to pollute my house with toxic fumes, and I opened the PSU.

Unfortunately I can't see anything wrong ... Any ideas ?

Purple smoke... so perhaps something purple? 😀

Usually smoke would come from the hot side of the PSU, since it is dealing with high voltage. The 2 blue caps at at centre right side looks like safety caps, and the right most looks like having some charred marks, so maybe you could check it out.

It's quite an unusual layout though, with hot side at the right and bottom, and the output side at top left.

The "charred mark" on the blue cap is actually a printing (probably the brand).

Also one thing to notice is that it didn't trigger my breaker at all which means there's no short between the live and neutral, right ?

If they are indeed safety caps, then it depends whether they are X or Y safety caps (they look like Y to me, as the X cap is the big yellow one which can be seen marked on the board as CX2). Y safety caps are line-to-ground caps so they would fail open in order not to energize the chassis resulting an electric shock to the user. Other than the blue caps, I really can't find anything else that look burnt. There seems to be a blue component beside the line filter transformer (and the big warning sign), it is obscured and not sure what it is.

Just been getting back into putting an old PC together. I have a ICL DRS M40 Which I saved from my dad's work back in the 90s.
Still have to find a VGA cable and Keyboard/Mouse to try it out fully, but it powers on and searches the floppy, and only beeps once when turned on so promising.
Is there anything you can recommend that I do it hasn't been touched inside since the 90s.

Will probably look at putting a soundcard in of some sort.

before turning it on, make sure there are no shorts (the tantalum caps love to fail short) and pay attention to the PSU. Mine died like a week after I started playing with it (since then, I gave that PC to a museum, I never took the time to fix the PSU issue ... Hopefully they will peek into it someday 😁 )