I was able to overclock my 100CT motherboard, so I put that in my 110CT housing. Now I have a fully working 110CT and a 100CT with display and keyboard problems, and with 100CT stickers.

dylanrush wrote on 2025-07-08, 23:39:

I recently purchased a pair of Toshiba Librettos from eBay, a 110CT and a 100CT. […]
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I recently purchased a pair of Toshiba Librettos from eBay, a 110CT and a 100CT.

The 100CT unfortunately has some screen issues which was a little bit of a surprise to me but I didn't look at the eBay posting carefully enough.

The 110CT was sold as working but with a BIOS password, which I was able to bypass by shorting some pins on the parallel port ( https://www.youtube.com/watch?v=qNbR3g8whD0 ). Once I was able to boot it, amusingly it hobbled into a Windows ME boot. But unfortunately, the keyboard was having some issues. The 9, O, L, < and up keys don't work. Of course those are all lined up vertically so there must be some trace between all of them.

No matter, I thought, I have one mostly broken Libretto anyway, so I'll swap the keyboards.

To my surprise, the other keyboard had the same problem! so there must be something wrong with this main board that would cause certain keys to fail. Dang it!

At this point I would like to fix the keyboard, or I guess I can swap the mainboards so the 100CT with the working keyboard can live in the 110CT housing with the working display. I also heard that you can overclock the 100CT anyway so it would be equivalent...

Any ideas about how I could go about fixing this keyboard? Maybe something is shorted on the main board?

Not shorted so much as battery corrosion that's visible in your picture of the mainboard, has quite likely disconnected some traces for the keyboard controller - the Toshiba chip labelled "471HP".
The Librettos in the Pentium / Pentium MMX era use a really complex and fancy multilayer board type for the time and some of the connections between layers don't have vias that go all the way through the board, which are particularly susceptible to being damaged by battery corrosion.
I think because the crystalline corrosion pushes apart the connection between the two layers - I've got more than one of these bad vias working again simply by pushing it back down, which is fine since they're just keyboard membrane signals.
I haven't seen that keyboard traces fault on the Libretto 100 since of my ones, one was perfect and the other was destroyed by battery corrosion and wouldn't post. However I have seen it on the Libretto 50CT and 70CT motherboards, where some rows / columns weren't working and it wasn't down to the keyboard itself, the signals no longer went from the mainboard's keyboard connector to the KBC - one was fixed simply by pushing down on a via and in another one I think I ran a wire instead 😀

If you want to keep the mainboard working long-term, I recommend to remove the RTC battery and clean the green battery corrosion up with isopropyl alcohol and something like a toothbrush or wooden toothpick and cotton buds. It may be worth at least temporarily removing the RTC battery connector from the mainboard to check under it, which since the corrosion usually weakens solder connections, can be done by simply sliding the connector forwards with some pliers, the solder connections for the pins of the connector will usually just come off because of corrosion. Which can then be cleaned up and reinstalled afterwards potentially.

Previously I would've recommended to use vinegar as well to neutralise the alkaline-based corrosion, but now I don't recommend that for two reasons:

• On this type of motherboard that would probably destroy a bunch of vias so I now recommend to avoid using vinegar on laptop mainboards unless it's a less complex area like the DC-DC circuitry. I don't think there are any simple areas on the Libretto 100 / 110 mainboard, it's packed.
• The corrosion did most of its work a long time ago, probably not much more potential for damage where it's low power circuitry

Great that you have one good one out of the two 😀