Xerox WorkCentre Pro 412 Service Manual page 107

Circuit Description
5-9-5 RING DETECTION PART
RING SIGNALS from the LINE section (TIP, RING) are further passed through C5, R3, ZD1, and ZD2 and
ends up at U9, (PC 814). U9 then detects above RING SIGNAL and passes the output to MAIN B'D. The
wire diagram's C5 is RINGER CAPACITOR and it normally uses 1UF/250V.
A R3 limits AC current and controls upper and lower REN meter.
WorkCentre Pro 412, FaxCentre F12 & 3/03 5-69
WorkCentre M15/M15i