The Clipper Add Value machines at Diridon do not accept cash. The cash-insertion slots have been welded over, which makes the VTA machines pretty useful, if you're in the south bay and riding, you know, VTA light rail or something. Beats hunting down a drug store, anyway, or riding up to Fremont to use a BART machine -- if you're in the south bay, I mean. Click the Clipper link above, enter a San Jose zip code and you'll see a list of lots of VTA machines, a few Walgreens, and a very few grocery/non-chain drug stores.
I've been told the contractor who supplied the Clipper Value Add machines went out of business just after delivering the machines; they also seem to run Windows 3.0 on a land-line modem and are as big as a $2500/monthly studio apartment in SF.