Samsung SCC-B2300 Service Manual - Page 79

Sync system unctions as Internal or Line Lock, y REAR BD S, 1LLON s statusON/OFF, 2-3 Function E - scc b 2300

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Circuit perating escription 13-2-2 Sync system unctions as Internal or Line Lock y REAR BD S 0 -1(LLON) s status(ON/OFF) 1) OFF(HIGH) : Internal Mode 2) ON(LOW) : Line Lock Mode 13-2-3 Function E planation Internal Mode 1) Switch(SW404-1(LLON)) OFF(LOW) the REAR BD 2) System changes to Internal Mode because XLLON = LOW, XLLOFF = HIGH are output. 3) XRST resets the IC101(in SCC-B2XXX(P) series, XRST pulse is output by u-COM(IC108-21). In SCC-B1XXX(P) series, XRST pulse is made by IC107 and IC1156, then goes to IC114.) ig. 3) IC153 decide the frequency by IC151 and X101. • SCC-B2391 / SCC-B1391 : 28.636363MHz • SCC-B2391P / SCC-B1391P / SCC-B2091P / SCC-B1091P : 28.37500MHz • SCC-2300 : 38.13986MHz 4) IC115 and R138, L104, C128 blocks the MCK(IC101-43) frequency. 5) ECK(IC101-88) is selected by IC151 and X101, so system works using 1 CLOCK. Line Loc Mode 1) Switch(SW404-1(LLON)) ON(HIGH) the REAR BD. 2) If the POWER BD input is AC, LINE LOCK PULSE(LPULSE) from the POWER BD is supplied to MAIN BD through AI Board. XLLON = HIGH, XLLOFF = LOW is output and system changes to LINE LOCK Mode. 3) XRST resets the IC101(in SCC-B2XXX(P) series, XRST pulse is output by u-COM(IC108-21). In SCC-B1XXX(P) series, XRST pulse is made by IC107 and IC1156, then goes to IC114.) ig. 4) ECK is selected to 27MHz(IC153 is oscillated by IC152 and X102) and supplied to ECKECK(IC101-88). 5) PCOMP(IC101-42) compares the Line Lock Pulse(XPULSE : IC101-44) and Vertical Drive Pulse phase which is oscillated by MCK(IC101-43), then supply the comparing signal to PLL(IC103). 6) PCOMP signal is integrated at IC103 and Q101. DC voltage is supplied to VCO block. DC voltage of TP101 should be 2.5Volts by adjusting variable condenser C130. (See the Adjustment guide) 7) VCO which is composed by D102, C127, R138, L104, C128, IC115 changes the frequency by DC value of PCOMP, and supplied to IC101-43(MCK). • High Model : 2.2uH • Normal Model : 1.2uH 8) Above 5~7 process is repeated until the phase and power input frequency becomes same. 9) COLOR signals works with ECK, and Y signals and other pulses work with MCK. Therefore, system uses 2 CLOCKS. Samsung Electronics

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13-2-2 Sync system unctions as Internal or Line Lock
y REAR BD S
0 -1(LLON) s status(ON/OFF)
1)
OFF(HIGH) : Internal Mode
2)
ON(LOW) : Line Lock Mode
13-2-3 Function E planation
Inter
nal Mode
1)
Switch(SW404-1(LLON)) OFF(LOW) the REAR BD
2)
System changes to Internal Mode because XLLON = LOW, XLLOFF = HIGH are output.
3)
XRST resets the IC101(in SCC-B2XXX(P) series, XRST pulse is output by u-COM(IC108-21). In SCC-B1XXX(P)
series, XRST pulse is made by IC107 and IC1156, then goes to IC114.)
3)
IC153 decide the frequency by IC151 and X101.
•
SCC-B2391 / SCC-B1391 : 28.636363MHz
•
SCC-B2391P / SCC-B1391P / SCC-B2091P / SCC-B1091P : 28.37500MHz
•
SCC-2300 : 38.13986MHz
4)
IC115 and R138, L104, C128 blocks the MCK(IC101-43) frequency.
5)
ECK(IC101-88) is selected by IC151 and X101, so system works using 1 CLOCK.
Line Loc Mode
1)
Switch(SW404-1(LLON)) ON(HIGH) the REAR BD.
2)
If the POWER BD input is AC, LINE LOCK PULSE(LPULSE) from the POWER BD is supplied to MAIN BD
through AI Board.
XLLON = HIGH, XLLOFF = LOW is output and system changes to LINE LOCK Mode.
3)
XRST resets the IC101(in SCC-B2XXX(P) series, XRST pulse is output by u-COM(IC108-21). In SCC-B1XXX(P)
series, XRST pulse is made by IC107 and IC1156, then goes to IC114.)
4)
ECK is selected to 27MHz(IC153 is oscillated by IC152 and X102) and supplied to ECKECK(IC101-88).
5)
PCOMP(IC101-42) compares the Line Lock Pulse(XPULSE : IC101-44) and Vertical Drive Pulse phase which is
oscillated by MCK(IC101-43), then supply the comparing signal to PLL(IC103).
6)
PCOMP signal is integrated at IC103 and Q101. DC voltage is supplied to VCO block. DC voltage of TP101
should be 2.5Volts by adjusting variable condenser C130. (See the Adjustment guide)
7)
VCO which is composed by D102, C127, R138, L104, C128, IC115 changes the frequency by DC value of
PCOMP, and supplied to IC101-43(MCK).
•
High Model : 2.2uH
•
Normal Model : 1.2uH
8)
Above 5~7 process is repeated until the phase and power input frequency becomes same.
9)
COLOR signals works with ECK, and Y signals and other pulses work with MCK. Therefore, system uses 2
CLOCKS.
Circuit
perating
escription
Samsung Electronics
ig.
ig.