Sony CPD-G400 Training Manual page 21

Active Off Mode Entry
SCR device D616 starts the Active Off Power Mode. The 200V and 8V
lines are connected when D616 turns ON. The increased voltage on the
8V line requires an immediate correction by the switching power supply
(IC603).
If the 8V line is not restored to 8V within a period of time, the power supply
(IC603) enters the Active Off Power Mode. In this mode, the oscillator is
only operated for a few cycles in bursts. This reduction in power drops
almost all the switching power supply output voltages.
The 8V-output line to the CPU (via IC609) requires so little power it can
operate in this low power mode with sufficient voltage. Standby regulator
circuit (Q609) is used to maintain the standby voltage in this Active Off
Power Mode.
Active Off Exit
When the computer is turned ON, the CPU IC1001 detects sync. To
wake up the monitor from the Active Off Mode, CPU IC1001 turns ON the
Remote On/Off output. This places a load on the 8V line. The load is
sensed by the switching power supply via Q609 (IC603 turns on) the os-
cillator full time instead of in bursts. This continuous oscillator output
provides sufficient power to maintain the 8V line with a full load.
Protection
The CPU monitors several sections and enters the Active Off Low Power
Mode to drop power for protection. The CPU monitors the following cir-
cuits:
Circuits Monitored
Circuits
HV Regulator Circuit
(Excessive Flyback voltage)
RGB Cutoff Circuit
(Excessive ABL Voltage)
Vertical and Horizontal Output
LED Indication
Both Green and Orange LEDs blink
at 1 Hz.
Both LEDs blink : ON = 1 sec,
OFF = 2 sec.
Both LEDs ON = 2 sec. OFF = 1 sec
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Although a failure in any one of these circuits can trigger the Active Off
Power Mode, the CPU will indicate the defective circuit using the front
panel LED.