AR 10046246, Operating And Service Manual

Page: 37 / 46

Model 125A250
Rev B 19
3.4 CONTROL SYSTEM
3.4.1 A4 Control/Fault Board (Schematic #10042218)
The A4 Control/Fault board consists of one 16-bit microcontrollers and several other ICs that monitor and
indicate the status of the amplifier. Power is supplied using only a single 5-volt power supply. The board
offers the following:
Feature Quantity
Open drain outputs 4
Digital outputs 6
Digital inputs (5-volt tolerant) 24
Analog outputs 2
2-channel encoder input 1
Inputs for a keypad 6
Display connectors 1
Serial communication jacks 2
3.4.2 A5 Interface Board (Schematic #10020073)
3.5 A10 VOLTAGE REGULATOR BOARD
The A10 Voltage Regulator Board contains two adjustable positive voltage circuits employing Linear
Regulator ICs U4 and U5. U4 accepts a +34 VDC input and outputs the +24.5 VDC Drain Voltage for the A1
preamp module. U5 accepts a +34 VDC input and outputs the +24 VDC supply voltage for the B1, B2 Fan
Assemblies.