... might know of a modern (or more importantly available) equivalent?
I can't find one in my books. It's a 3.5A controlled avalanche
rectifier diode, the 'controlled avalanche' bit is quite important as
they are from a switcher PSU.
Jim
The data sheet indicates trr=3uS for the now discontinued BYM56E
which makes it a standard recovery type (ie. not fast or super-fast),
so there are a few possible types I would try.
I assume the PSU is an off-line 230Vac SMPS for use in the UK?
I doubt that the 3.5A Ifav rating is strictly needed and you could get
by with one specified at 3A such as the BYW86 (probably not readily
available)
http://www.vishay.com/docs/86051/86051.pdf
Also, I don't think the 1000V rating is strictly necessary for a
230Vac input and you could get by safely with 800V types. The old
venerable 1N5627 has been used successfully in off-line switchers and
would be readily available.