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So I have this old capacitor from a Sunbeam Mixmaster (model 9B). It has three legs, and no markings that I can use to determine its value. On the case is

Ducon capacitor Pat. No pn441 250v AC MX197c

Duckduckgo and Google have failed to enlighten me, I even tried patent searching. Ducon was an Australian manufacturer, but it's faded into obscurity, hampered by the fact that there are now dozens of companies called Ducon.

3 legged capacitor marking: mx197c 3 legged capacitor showing points of connection, marking: pat no. pn441 250v ac

Anyway two of the legs are connected to the active and neutral wires from the plug, the third is connected to the grounded chassis (!). I've marked the photo to show where they connect. The capacitor has become conductive and so now it trips the RCD breakers whenever it's plugged in.

From what I've gleaned the part is probably just two capacitors with a common ground. I'm guessing they're just to suppress interference from the motor governor, which worked by having centrifugal force make and break connection to the motor. There is another .05 mfd capacitor in parallel to a resistor across the governor, but it seems to be fine.

In the original circuit diagram it's called the Motor Condensor. No mention of values or ratings in the service manual.

original 9b circuit diagram

What value capacitors would work as a replacement?

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    \$\begingroup\$ If one of the two caps are still good, you might measure it; likely, their the same value. \$\endgroup\$ Commented Feb 27, 2022 at 5:28
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    \$\begingroup\$ You could try 2 4n7 Y caps to ground and 1 100n X cap between PN . \$\endgroup\$
    – Autistic
    Commented Feb 27, 2022 at 5:49

1 Answer 1

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Two 0.01 μF 400 V metallised film, Class Y safety (line-to-ground on case) capacitors would suffice.

enter image description here

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    \$\begingroup\$ They have to be class-Y safety capacitors though, because they're connected to the chassis, right? \$\endgroup\$
    – stib
    Commented Feb 28, 2022 at 1:47
  • \$\begingroup\$ Yes, thank you. I have edited my answer accordingly. \$\endgroup\$
    – vu2nan
    Commented Feb 28, 2022 at 4:27

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