This is just part of a rather painful saga. Recently arrived: two HP 8118A pulse/data generators. The first known to power up but turns out to have a CPU board badly corroded by a leaked NiCad, the second clean but has a dead power supply.
So obviously, put the good PS in the clean machine.
I suppose I'd better mention that due to dismay on discovering the unit 1 corrosion, and so never powering it up, I had neglected to switch it to 240V. Even when installing that PS in unit 2. So there were initial fireworks provided by three MOVs going bang. But no other damage. Replaced them, switched to 240V, tried the PS by itself - OK. Plugged it in and the machine runs. Yay!
Runs for about two minutes before going bang again. Except this time the stinky RIFA smoke kind of bang. Huh? But I'd changed the one RIFA cap on the board already! Where did the smoke come from?
Ladies and gentlemen, may I present you the Schaffner model FU mains filter.
AKA brick of unrepairable stinky RIFA death.
So, apparently it contains at least one RIFA cap which couldn't take 240VAC. I opened the soldered-on lid, hoping to be able to melt out the potting material and repair/replace the contents. Previous metal case mains filters I opened had used tar for potting.
Nope, it's a tough epoxy.
Hmm... well the 2nd unit seems newer. Same custom mains filter but it looks like a later manufacture. Maybe they'd stopped using RIFA caps?
Let's see. I set it up by itself on a bench with mains applied. Let it sit for several hours. No bang.
OK, perhaps it will be OK. I installed it in the power supply. The machine runs again. And then half an hour later goes bang. This Schaffner FU has blown a RIFA cap too.
Great. So now I have two blown, unrepairable mains filters, of a special shape and with custom mounting screws. Fantastic.
FU Shaffner and RIFA.