Don't know, but since you're going to replace it anyway, you can de-solder it from the board with its pins intact, then use a DMM to test it. If you put it in capacitance mode and get 0, you can rule out it being a capacitor. It could be a resistor, but most resistors look like the tan ones with the stripes. Honestly, you got me.

It looks like a diode?

[EDIT:] Incidentally, electrical components marked with L on boards tend to be Inductors.

looks like a diode, but I dont see any bar on it indicating polarity. Usually diodes are 'D' and inductors are 'L'.

you can see 'd1' below the rom so probaly the L3 is not a diode..

I'd make a guess that its an axial power inductor.

Not sure why but first my eyes catched broken tantalum capacitor.

It is obviously an inductor. Unfortunately you can't measure the parameters without special equipment. You can try soldering a 1uH or 10uH inductor and maybe you'll be lucky.

With schematics using PS/2 keyboard connectors often use 10uH inductors. That would be a good place to start.

Can you do a continuity check on the part, and tell to which pin of the keyboard connector it leads? It's probably a fuse.

I've seen inductors placed instead of fuses on some boards - maybe here it's the other way around.

It is called a ferrite bead. I suppose they could be considered as inductors because they are pretty similar.

It might relate to the burned tantalum.

Can you determine which keyboard wire (clock, data, 5V supply, ground) goes through the burned inductor?

Maybe the keyboard was broken and drew too much current, burning the ferrite bead?

Thanks you all guys, I'm not good at all with these

Here are the 3 keyboard port pins that are directly connected to the mystery components (as you're looking the keyboard port from the front):

rein_ein wrote:

Not sure why but first my eyes catched broken tantalum capacitor.

Yeah me too, C73 ... 99.9% is the same value as the ones near it - needs replacing too!

The other part is a ferite/filter (like Jolaes mentions) check continuity and see if you have it: If not you can use a wire patch to test if the keyboard works after that.
I'd replace both parts at once 😎

The capacitor has been already replaced!

konc wrote:

Not the blown tantalum capacitor, the photo is old and it has been changed. I'm talking about the marked L3 component.

So if it's certain it's an inductor by now, I see inductors also have additional metrics, check out for example this local site I'm planning to buy them from:
10uH: http://www.acdcshop.gr/axial-c-54_252_255_en. … l?f=221_2539%2C
Which one do you think I should get? It's not going to blow up the rest of the motherboard on my face or anything if values are not correct, right?

L1 and L2 are certainly inductors/ferrite beads - but L3 is different. The shrinkwrap on it may have an imprint. It's in the 5V path - a fuse would make sense there.

I've seen ferite in many power lines , I am pretty sure this is just another ferite (maybe not the same value as the other two since it's on the 5v line)
If it was a fuse surely they'd name it "Fsomething" and not L3, right?

konc did you bridge the connection to see if it fixes the keyboard problem?

h-a-l-9000 wrote:

L1 and L2 are certainly inductors/ferrite beads - but L3 is different. The shrinkwrap on it may have an imprint. It's in the 5V path - a fuse would make sense there.

Good catch!

Now, in retrospect, the first thing to do would have been to search for images with working identical motherboard:
http://www.amoretro.de/wp-content/uploads/mor … motherboard.jpg

The L3 filter for the 5V supply line has been changed to a fuse indeed.

And also : ferrite beads very little inductance so it usually can't be replaced it with 10uH inductor. Not sure if it would have worked in this case though, since L3 is for supply voltage.

^ now that is a good catch, that pic cleared everything up - h-a-l-9000 was correct... good one!
So what rating of fuse would go there?

keropi wrote:

^ now that is a good catch, that pic cleared everything up - h-a-l-9000 was correct... good one!
So what rating of fuse would go there?

Hmm, I think no keyboard draws more than 200-300mA, so maybe 500mA would be safe value to allow to pass out from connector in normal conditions, so maybe around 750mA or 1A fuse rating would be good.

hmmm I just checked the 2 486 mobos I have , they definitely don't have any fuses at the keyboard port, just ferite beeds. Maybe upgrading the vcc one to a picofuse is not a bad idea after all...

Konc if you have a 1A glass fuse (that are common as dirt) just do a quick solder job to see if the board works, maybe there is nothing damaged or maybe something will blow the fuse again... lotto 🤣

OK, so we're set? A fuse 0.75-1A is the verdict? Let me see what fuse I can find and give it a quick try.

Thanks for everything guys, I will report back with the results. If I don't it means the fire brigade arrived too late 😀

yep, 0.75/1A fuse sounds correct... if you have try with the 0.75 one - worst case scenario it burns