And thanks very much to you Sean and also to Mike (Cobaltblue) and Jeremy (Pamphonica) for the Heiden 30V, 10A supply. You described it I think as a 'hefty lump' and oh yes it is - 25kg and built like the proverbial brick outhouse ! It's a lot of psu for a tenner. And I particularly appreciate Mike's and Jeremy's efforts in heaving it across to me. I did have to hammer one of the chassis side-members and the lid itself square (well, roughly square) so I could get the lid to fit back on again. But despite that the unit came on as soon as I powered it up. Tests with a DMM and a scope showed the output was pleasingly stable and pretty well noise-free
.
There was one problem however. Both the voltage and current displays on the front panel were showing significant noise, about 0.4V pk-pk amplitude and appearing to oscillate at a few hertz. I wasn't too worried because the supply itself was working fine but it was irritating. I contacted Heiden but they have no schematics or manuals dating back that far (1988 I think). So I just had to start taking the thing to bits. Fortunately the problem was easy to spot. The arrowed component on the second card in (see pic - maybe some kind of clock crystal ?) had half fallen out of its sockets. Also a track repair on the first card had failed, although that might have happened during disassembly. Anyway I pushed the loose legs of the 'crystal' back in and resoldered the track bridge and all now seems well
. So thanks again folks !
Cheers,
GJ