Ian wrote: H Paul, I've been thinking about adding some high value (>=220k) pull-ups to the unlit cathodes. Do you have any opinon on that? It's a bit of a sweat and a lot of extra components, and propbably not at all necessary, but this is a recurring problem, and always causes consternation.
Another solution would be push-pull drivers, I suppose... The HV5622 is open-drain, nad there does not seem to be an equivalent part in push-pull (80V seems to be the limit).