Originally Posted by JimS
According to the service manual, EMI401 is a noise filter listed as 100pf. On the actual schematic, its drawn as a resistor with an extra lead going to ground... I'm assuming that's a 100pf capacitor to ground. It says 4.7 next to it, but no multiplier... In any case, the 5v to both joystick ports goes through it, so if you've got the 5v on the ports, I'd say EMI401 is OK.
That's interesting, as on the motherboard it's clearly a 1/4 watt resistor. There are three holes at the site of EMI401 on the silkscreen, though the resistor just connects between two of them.