Samsung ML-920 Service Manual page 170

CIRCUIT DESCRIPTION
3-7-5. 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 wilre diagram's C5 is RINGER CAPAC-
ITOR and it normally uses 1UF/250V.
A R3 limits AC current and controls upper and lower REN meter.
3-8 SMPS (Switching Mode Power Supply) Unit.
3-8-1 SMPS SPECIFICATIONS
The SMPS (Switching Mode Power Supply) Unit used here is a PWM (Pulse Width Modulation) type power supply unit that
supplies DC+5V to controller and control panel, and DC+5V, DC+24V and DC+12V to the engine. It also supplies AC power
to fixer heat lamp.
No. Output Channel
1 Channel Name
2 Rated Output Voltage
3 Rate Output Current
4 Maximum Load Current
and Load Pattern
5 Load Change Range
6 Rate output voltage
(For rated I/O)
7 1) Total Output Voltage
Deviation
(Input, Load, Temp., Aging)
2) Dynamic Input Change
3) Dynamic Load Change
8 Refer to ripple & noise 27)
9 Refer to load short and
overload protection 23)
Refer to load short and
overload protection 23)
Repair Manual
3-40
Ch.1
+5.1V
+5.1V
2A
3A Continued
0.5~2.0A
+5.1V±5%
(+4.84~+5.35V)
Including All
+5.1V±5%
(+4.84~+5.35V) (+21.60~+26.40V)
Including Set Error Including Set Error
150mVp-p or less
Must not ignite or
generate smoke
when output shorted the range of
for 5 sec.
- This Document can not be used without Samsung's authorization -
Ch.2 Ch.3
+24.0V +12.0V
+24.0V +12.0V
2.5A 1.0A
3.5A Continued 1.0A Continued
0.3~2.5A 0.2~1.0A
+24.0V±10% +12V±5%
(+21.60~+26.40V) (+11.40~+12.60V)
Including All Including All
+24.0V±10% +12V±5%
(+11.40~+12.60V)
Including Set Error
500mVp-p or less 150mVp-p or less
Output voltage must Must not ignite or
shutdown withing generate smoke
when output shorted
3.5A~6.5A for 5 sec.
Samsung Electronics