[Robotgroup] EMI suppression on power supply

[Andre Lamothe]

The capacitor is simply to shunt high frequency noise from the front end of 
the step down transformer and from the rest of the low voltage regulators as 
well. But, the resistor is questionable. So you are saying the resistor is 
in parallel with the capacitor?

Andre'


----- Original Message ----- 
From: "Def Egge" <robodigest at innervate.com>
To: "The Robot Group" <robotgroup at puremagic.com>
Sent: Sunday, March 16, 2008 7:42 PM
Subject: [Robotgroup] EMI suppression on power supply



I am looking over a non-functioning power supply (removed from a
mid-1990s desktop system).  I see at the 110VAC power connector a 330
nF capacitor (p/n RIFA PHE-830 M) installed between the 100VAC hot
and neutral leads, I presume, for EMI suppresion.  Is this correct?

The leads of the capacitor are, in turn, connected by a 500 ohm
(according to my DMM) 1/4-watt resistor (green-red-brown-gold).  The
gold band indicates 5% tolerance, so this is a 520 ohm resistor (+/-
26 ohm), correct?  What is the purpose of the resistor?  Curious
minds desire to know more.


-- 

All the best....

Mike

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