20
POWER SUPPLY SAM-1C
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7.2 Power supply unit :
The current versions of the SAM-1C are equipped with the "ultra-low-drop" precision power supply SMPS-
12. This modern switching power supply produces extremely stable and pure supply voltages with
minimized power consumption and lower heating compared to conventional power supplies. Magnetic
interference fields, which can lead to hum in neighboring devices, are reduced by approx. 90% in this
power supply compared to conventional power supplies. The power consumption and thus also the
heating is reduced by this switching power supply technology by typ. 30..40%, the life span of the
components is thereby increased. The SAM-1C with switching power supply has fully equipped with 4
channels only a typ. Power consumption of 4.0 W.
The output voltages can be loaded up to 250 mA. At higher currents, the current limitation becomes
active and lowers the supply voltages. At the same time this is indicated by the "
Power
"
LED
on the
front going out. The internal supply voltages of the amplifiers are +/- 19.7 volts. Short-circuiting the
output voltages will not damage the power supply.
When the power supply is switched on, it is gently boosted to full
supply voltage in approx. 0.2 seconds. Switching on the power supply
does not cause any crackling noise on the mains side or in other audio
devices.
The
adjacent
measurement
chart shows
the
power
consumption during the switch-on process. No interference peaks can
be detected.
To prevent damage to amplifiers and loudspeakers in case of overload
or short-circuit of a supply voltage, the power supply has a monitoring
of the symmetry of the output voltages. If a defined limit value for the
symmetry is exceeded even minimally, the device switches off. The red
power LED goes out.
Timer:
the SMPS-12T power supply has a "Power-Down-Mute" circuit that controls relays on the audio board
outputs. This largely avoids "power-on crackles" when switching a sound system on and off, or eliminates
existing power-on noises. The switch-on time is about 6 seconds, the switch-off time a few milliseconds
after falling below the minimum bias voltage. These control voltages are applied to the 10-pin connector
pin 7..10.
Power supply SMPS-12T
CONNECTOR PIN ASSIGNMENT CN2 10-pol.
Pin 1
+ 19,7V Power-On-LED +
(Rv= 8k25)
Pin 2
GND LED
Pin 3
- 19,7V Power-On-LED -
(Rv= 8k25)
Pin 4
+ 19,7V Audio
Pin 5
GND Audio
Pin 6
- 19,7V Audio
Pin 7
+ 19,7V Mute-Relais A
Pin 8
GND Mute-Relais A
Pin 9
GND Mute-Relais B
Pin 10
- 19,7V Mute-Relais B
TESTPUNKT
+19,7V
TESTPUNKT GND
TESTPUNKT
–19,7V