DIYbanter - View Single Post - Westwind Trantor Hard Disk for Osborne Computer

Rayner Lucas

In article ews.com,
says...

On 5/18/21 2:05 PM, Mike wrote:
In article ews.com,
John Crane wrote:
Turns out these use the problematic Astec power supplies identical to
the ones used in the Osborne 01. There is a 0.1uF 250V polymer cap that
tends to blow.

Is it a RIFA Yellow/clear/foil looking thing, wired across Live/Neutral
as part of the incoming filtration?

Exactly! It is a RIFA.

RIFA filter caps are evil little devices. They don't just tend to blow,
they *will* blow, with a thick plume of absolutely foul clinging smoke.
They can turn up in just about any mains-powered equipment from the 80s
or 90s, from kitchen appliances to computers to high-end test gear. Any
vintage equipment that plugs into the wall should be considered suspect
until you've checked its power supply to make absolutely certain of the
absence of the damned things.

They should be replaced with equivalent safety capacitors with the same
X or Y rating, never with a normal capacitor. The equipment will also
generally work without them, though without the associated protection
against generating or receiving EMI.

I once dug *eight* RIFA caps out of the power supply in a Tektronix
VM700T test set, only for the back end of the Schaffner branded power
inlet to explode instead. It turns out that Schaffner filtered power
inlets *also* contain RIFA capacitors, concealed inside a metal casing
and some sort of potting material for an especially unwelcome surprise.

I've also seen a near-identical type of cap under the WIMA brand. These
seem much rarer but are just as treacherous.

I expect Mike's right about the drive, I'm only posting because I've
developed a very specific grudge against these things.

R