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1.
Circuit description
1.1
Power circuit
(1) The power block is compatible with 100 to 120VAC/220 to 240VAC. (Automatically tracked)
(2) The power supply section is a PRC (ON width control with constant OFF time) during P-SAVE, and
operates as a pseudo-resonance circuit in the steady state.
By feeding back via the photocoupler IC903 from the output voltage with the HIC (STR-G6452)
flyback converter type switching IC (IC901) with built-in POWER-MOS FET and separate-exciting
control IC, the voltage is constantly controlled to prevent output voltage fluctuations caused by AC
input voltage fluctuations and secondary side load fluctuations.
(3) Switching of the PRC and pseudo-resonance is controlled by inputting to IC901 via IC905 with a
microcomputer signal.
(4) The secondary side output voltage of this power circuit is a single-phase 12V.
Microcomputer signal (J901 1 PIN)
IC901 oscillation frequency
Standby mode
(PRC mode)
L
Approx. 20kHz
Normal mode
(pseudo-resonance mode)
H
Approx. 50k~150kHz
<Block diagram>
AC100~120
220~240
Transformer
Vcc
IC901
F/B
IC903
12V
IC905
Starting resistance
To inverter
To main
IC904
+B
EMI filter
Rectification
Rush
prevention
HIC control IC
Shunt
regulator
P-SAVE
microcomputer
signal
Summary of Contents for NEC MultiSync LCD1550X LCD1550X LCD1550X
Page 88: ...SCHEMATIC DIAGRAM POWER LCD1550X Normal Power Save 1ch Pin 4 2ch Pin 1 3ch Pin 2 4ch Pin 5...
Page 89: ...SCHEMATIC DIAGRAM PWB MAIN POWER LCD1550X...
Page 90: ...SCHEMATIC DIAGRAM PWB MAIN INPUT LCD1550X...
Page 91: ...SCHEMATIC DIAGRAM PWB MAIN SYNC LCD1550X...
Page 92: ...SCHEMATIC DIAGRAM PWB MAIN TMDS LCD1550X...
Page 96: ...SCHEMATIC DIAGRAM PWB MAIN ASIC LCD1550X...
Page 97: ...SCHEMATIC DIAGRAM INVERTER LCD1550X 1ch Q701 B 2ch Q702 B...
Page 98: ...SCHEMATIC DIAGRAM PWB SW LCD1550X...
Page 100: ...SCHEMATIC DIAGRAM POWER LCD1550X...
Page 101: ...SCHEMATIC DIAGRAM PWB MAIN POWER LCD1550X...
Page 102: ...SCHEMATIC DIAGRAM PWB MAIN INPUT LCD1550X...
Page 103: ...SCHEMATIC DIAGRAM PWB MAIN SYNC LCD1550X...
Page 104: ...SCHEMATIC DIAGRAM PWB MAIN TMDS LCD1550X...
Page 105: ...SCHEMATIC DIAGRAM PWB MAIN MC LCD1550X...
Page 106: ...SCHEMATIC DIAGRAM PWB MAIN ASIC LCD1550X...
Page 107: ...SCHEMATIC DIAGRAM INVERTER LCD1550X...
Page 108: ...SCHEMATIC DIAGRAM PWB SW LCD1550X...
Page 127: ...16 Document No VSPF A028 Bave Average brightness of 1 to 9 10 50 90 90 10 50 5 1 2 3 6 9 8 7 4...
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