23 Jan
2016
23 Jan
'16
7 p.m.
On Sat, 23 Jan 2016, tony duell wrote:
Incidentally, some machines have those sealed metal
cans containing
filter capacitors, inductors and sometimes discharge resistors [2]. Has
anyone ever had the capacitors in one of those fail?
Actually, yes. I had one fail in one of my scopes. I don't recall the
brand/series right now, but it is apparently a known issue with that
particular series of filters. I still need to replace the same filters in
the other scopes since they will most like do the same thing eventually.
[2] I wish the manufacturers would print a schematic
on the can, or at
least in an available data sheet. If I measure a 1M leak to earth from
the live pin (say), I want to know if it's a deliberate discharging
resistor or a leaking capacitor.
Most of the IEC320 input filters I've used have a schematic on the can or
in the datasheet. They are usually also careful to denote the
medical-rated filters which lack the Y-type safety capacitors between the
two supply terminals and ground.