Re: Peripheral A/B switch indicates opposite of the Active Side
If a problem is encountered, particularly after replacing an Alarm Arbiter Card (AAC), where the peripheral equipment A/B selector switch(es) indicate
a selection opposite of which side of the VCO is Active (i.e., VCO A side Active - peripheral A/B switch shows B side selected), it may indicate that Jumper J4 on the AAC is installed incorrectly.
To correct the problem, remove the AAC (this requires turning off the VCO power) and locate Jumper J4 as shown in the figure. Ensure the jumper is positioned near Resistor R31 as shown. When the jumper is in the correct position, reinstall the AAC and apply power to the VCO. The peripheral A/B selector switches should now indicate the same side active as the VCO.