Xerox FaxCentre F12, Service Manual

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Circuit Description
5-68 3/03 WorkCentre Pro 412, FaxCentre F12 &
WorkCentre M15/M15i
5-9 LIU PBA
5-9-1 SUMMARY
LIU WIRE CONNECTS Main B’D’s MODEM AND LINE PARTS, AND IMPEDANCE MATCHING (AC, DC),
RING DETECTION PART and LINE SEIZURE (DIALER).
5-9-2 DC MATCHING PART
Normal movement range of LIU is 12mA to 9mA.
Adapting CTR21 standard, the regulation limits to 60mA CURRENT flow through the terminal.
Therefore, select (*:for EU PIT) Option to connect necessary items then the current through LIU will not
exceed 60mA.
• CTR21 Standard (Europe): 12mA~60mA • OTHER Standard (U.S.): 12mA to 90mA
DC has a character to pass through the LINE. And with Q1 (VN2410) GATE section’s LINE INPUT cur-
rent and Q1 Source connection to R20, can be decided as follows:
•
-VDCR = VL1 + ILINE X R20.
(VDCR: Tip-Ring CD Voltage, ILINE:
Current flow)VL1:Line Input Voltage, VL1 = VBD1+VCE(Q2)+VDS(Q1).
5-9-3 AC MATCHING PART
Basic LIU’s AC IMPEDANCE is 600 and uses R47. 48. C36 to possibly control combined IMPEDANCE.
• U.S. Usage: A terminal IMPEDANCE Æ 600W(±30%).
• CTR21: A Terminal IMPEDANCE Æ 270+750W//150nF.
5-9-4 DIALER PART
*MF DIAL
DTMF Dialing is controlled by MODEM and should be selected by appropriate LEVEL and On-off Time
output based on each countries’ own National specification.
• Frequency Tolerance: ±1.5%.
High Group: 1209, 1336, 1477, 1633Hz.
Low Group: 697, 770, 852, 941 Hz.
*DP DIAL
Controls from MAIN through / DP-Terminal.
for U.S.Usage, set time to DF signal of 40:60 M/B. DP signal is made of U6 (pcb817). The DC current
which flows through Q2 Base is regulated by On/Off switch and turns to DP dial signal with a COUPLER.
• CTR 21 does not have telephone capability but has the number 3 and 4 Line Connection. No DP
condition but possibility to get approval only on DTMF Dial based terminal.
U.S. Usage CTR21
High Frequency Level -9.0+2.0/-2.5 -7.0 +1.0/-2.0
Low Frequency Level -9.0+1.0/-2.0 -11.0+2.5/-2.0