[E] The PROT_6(M_B_DOWN, pin75) is the port to detect abnormalities of
the power supply circuit
(1) Detects abnormalities in the power supply circuit of the DIGITAL circuit.
Detects voltage reduction (about 6.6V) in +12V of the DIGITAL circuit power supply, then [
Q1006,
Q1007] turns off and "PROT_6" changes from "Hi → Lo".
If "
PROT_6" changes from "Hi → Lo" when the above abnormality is detected, the protection circuit acti-
vates. "
POW_1 : pin72" and "POW_2 : pin73" change from "Hi → Lo" and power relay [S8801, S8802]
immediately turns off and shuts down.
The STANDBY indicator flickers to inform that an error has occurred.
This protection operation is intended for when a breakdown of the power supply circuit occurs and im-
mediately shuts off the power in order to avoid the risk of damage.
To check whether the power supply circuit is broken, turn off the unit, then wait for about 1 minute and
turn it on again.
This action will deactivate the protection operation.
If the "
PROT_6" remains in the "Lo" abnormal state, which constitutes an abnormality, the unit shuts
down approximately 3 seconds later and the STANDBY indicator starts flickering.
If the protection operation is not deactivated even after the power is turned on again, the power supply
circuit or main transformer may be broken.
POWER PCB
±7V for TONE circuit
+17V for OLED
+15V for LED
SPK output DC detection
±HV DIP detection
NC500
NC500
±HV Under Voltage
(Detected at ±HV 30V or less)
NC500
±HV Over Voltage
(Detected with ±HV 101V or more)
NC500
VDR Under Voltage
(Detected at VDR 13.5V or less)
NC500
VDR Over Voltage
(Detected with VDR 19V or more)
NC500
Temperature
(Detection of a temperature of 90°C or
higher near the thermistor)
NC500
SMPS600
SMPS600
Temperature detection
(Detects near the thermistor at 80℃ or higher)
Max output short circuit current(rail to rail) 7A DC *
Maximum power consumption 1100Wmax **)
Limited by over current protection
SCCPIND (Detected at output 26A or more)
(25A min./26A typ./28A max.)
FATAL
(Detected at DC with output 15V or more)
(Detected at 27V or less)
(Detected with ±1.5V or more)
HPA output DC detection
(Detected with ±2.2V or more)
Low Voltage detection
Low voltage / over voltage detection
+1.2V or less, +20V or more
Power supply fault detection
(Detection of an absolute value of 1.2V
for the midpoint electric potential)
±15V for pre AMP stage
Power supply fault detection
(Detection of an absolute value of 1.2V
for the midpoint electric potential)
Low voltage / over voltage detection
+8V/+24 is 2V or less, +3.3V is 8V or more
(Possible Factors)
(Possible Factors)
(Possible Factors)
(Possible Factors)
(Possible Factors)
(Possible Factors)
(Possible Factors)
(Possible Factors)
(Possible Factors)
· SPK output SHORT
· Temperature rise of NC500 by the overload
· SMPS pattern SHORT
· Decrease ±HV by overload
· Shut down SMPS
· DC generation on SPK output
· Decrease ±HV by overload
· Shut down SMPS
· DC generation on SPK output
· DC generation on HP output
· Main transformer connector missing etc.
· +15V series SHORT
· ±7V series SHORT
· ±15V series SHORT
· Power supply series SHORT
(Possible Factors)
(Possible Factors)
(Possible Factors)
Shut down SMPS
Protection by PM12 circuit
Protection by NC 500
Protection by SMPS 600
Shut down SMPS
Shut down SMPS
Before Servicing
This Unit
Electrical
Mechanical
Repair Information
Updating
53
