Gp 18 Pba Liu - Xerox WorkCentre M20 Service Manual

GP 18 PBA LIU

Purpose
To give information about the operation of the PBA LIU:
• Summary
• DC Matching Part
• AC Matching Part
• Dialer Part
• Ring Detection Part
NOTE: If necessary, refer to GP 20 for the acronym list and cross reference lists of more com-
monly recognised part names.
Summary
LIU wire connects main BD's MODEM and line parts, and impedance matching (AC, DC), ring
detection part and line seizure (dialer).
DC Matching Part
Normal movement range of LIU is 12mA ~ 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~90mA
DC has a character to pass through the LINE. And with Q1 (VN2410) GATE section's LINE
INPUT current 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)
AC Matching Part
Basic LIU's AC IMPEDANCE is 600 and uses R47, 48 and C36 to possibly control combined
IMPEDANCE.
• U.S. Usage: A terminal IMPEDANCE 600W(30%)
• CTR21: A Terminal IMPEDANCE 270+750W//150nF
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
Work Centre M20 Family
Refer to Table 1.
Table 1 Tolerance levels
U.S. Usage
High Frequency Level -9.0+2.0/-2.5
Low Frequency Level -9.0+1.0/-2.0
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.
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 BD. The wire diagrams C5 is RINGER CAPACITOR and it normally uses 1UF/
250V.
A R3 limits AC current and controls upper and lower REN meter.
March 2004
6-33
CTR21
-7.0 +1.0/-2.0
-11.0+2.5/-2.0
General Procedures and Information
GP 18