VOGONS

Keyboard controller IC

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First post, by vtech

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Hello,

I'm currently fighting an old system, I can't find any information, it is a Mitac Mistation 3S 3052E, it is a 386SX-20 system, besides a tantalum blown on the first power up, I'm fiddling almost with bad RAM and an occasional keyboard lock, today the case was different, the PC doesn't start and no activity in the the post card, I have a temperature gun and I noticed the keyboard controller warmer than chipset and CPU, those two around 20 Cº and the keyboard IC at 34 Cº, I remove it and the PC came to life, albeit not displaying image, gave me some beep codes and there is activity on the post card.

So, my question is if I can replace this keyboard IC with other similar or must be the same, and if this is in some sort programmable, because it as a sticker related to the Phoenix BIOS in this system, because I have a dead motherboard, also from a Mitac system, but a 486SX, the difference being this one as a sticker related to the AMI BIOS. And I was wandering if I can replace with this one?

The controller is a Intel P8742AH / L1275363

Reply 1 of 4, by vtech

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Update, touching the components around I came to this one marked in the image bellow, I don't know what component is this, looks like as a wire loop inside, somehow and it is a guess, this was a little twisted and the leg soldered to the board was touching one of the loops, and rendering the keyboard IC inoperable.
If someone can tell what is this component called or what is the function, just to rendered this post somewhat useful to someone else.

Reply 2 of 4, by dionb

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That's an axial inductor. The "L" marking on the board makes that clear. In a DC circuit, the main role of an inductor is to help filter high-frequency signals out of a power line, or (look at it another way) stabilize currents.

Reply 3 of 4, by vtech

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dionb wrote on 2025-01-02, 23:58:

That's an axial inductor. The "L" marking on the board makes that clear. In a DC circuit, the main role of an inductor is to help filter high-frequency signals out of a power line, or (look at it another way) stabilize currents.

Thanks for the explanation.

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