Thanks for these photos hasu, it would certainly be interesting to see what those engraved chips are. Can possibly make out an LV74A from one of them. The other large chip is a little blurry, can anyone get a better photo? Is there anything else hiding under the controller?
Edit: took a closer look at the photos. I have some initial thoughts but they are quite uncertain:
Z1 is the LV07A, driving the columns. It seems that there are two analog multiplexers taking row input: Z2 and Z3. The output line is joined near the bottom of the board and fed into the small cluster of components by the Topre logo. What are Z4 and Z5? I'm thinking voltage boost is done here, perhaps op amps of some kind. The output of this leads to R22 shown here
http://i.imgur.com/HrAuS0V.jpg after which presumably the sensing is done. I think the top chip in that photo is LV74A and the key state is held in the flip flop for the controller to read. Looks like the lines leading off to the top of that photo go back to the controller. Maybe the smaller chip is a variable resistor.
Interesting to note that there are a low number of columns (1 LV07A) compared to rows (2x LW051A) (if my guess is right anyway). Normal HHKB2 had only one analog mux. I think this is related to the change of sensing mechanism. Possibly the new method is less robust, leading to the problem of voltage drop when too many keys are on a single row. Of course this could all be completely wrong.
