Bought a 1997 Gossen Konstanter 40V 50A SMPS for 310 Euro.

Unfortunately it was partly dead: -OL means, that current measurement is off limits. Current measurement, power measurement and current regulation were dead.
Went back to sender.

More luck with a 1986 HP 6114A PS for 150 Euro. Came with this optics and is bang on from the start.

The .x V coding switch was bad. So I desoldered the switching unit, took it apart and flushed and dried the 4 single switches through holes. Same with U/I meter input selection switch. Now everything is fine.
And last but not least a 1978 HP 3455A for 140 Euro. Came fully functioning including the turbine sound fan

and deserves some minor cleaning:
