McCain ATC eX NEMA - 2.6 Internal Construction; Sub-Assemblies

McCain ATC eX NEMA Controller – User Manual 11
Version 1.0
2.6 Internal Construction / Sub-Assemblies:
This section briefly describes the construction and operation of each sub-assembly of the ATC eX NEMA
controller, indicating the interface connectors on each board and the relationship to the other boards.
For a more detailed understanding of a specific module or sub-assembly please refer to the proper
appendices.
Appendix A Contains all schematics.
Appendix B Contains the assembly drawings.
Appendix C Contains the bills of materials.
2.6.1 Power Supply Sub-Assembly (M45891).
This sub-assembly consists of a switching power supply module with a large can back up capacitor. It
provides the DC voltages to the Control Signals board (M66450A) and receives the AC power from such
board. The DC voltages provided are +24VDC, +12VDC and +5VDC.
2.6.2 Control Signals Board Sub-Assembly (M66450A).
This board generates the POWERDOWN, POWERUP and LINESYNC signals and along with the DC
voltages received from the power supply assembly. It also sends the signals and voltages to the other
sub-assemblies through the corresponding harness.
The board also defines the trip and recover window for the AC power input; this is a factory set
adjustment and should not be changed. The default is: 85VAC for power down and 90VAC for power up.
This sub-assembly contains the below circuits and connectors:
• A zero-crossing detector.
• Circuitry for generating the POWERDOWN, POWERUP and LINESYNC signals.
• An AC hysteresis trip/recover adjustment (POT1).
• A -12VDC power supply, it receives the +12VDC from the power supply sub-assembly (M45891)
and returns -12VDC to the P1 connector.
• A 12 positions connector (P1) for providing the DC voltages and control signals to the host board
(M69945A) and modem board (M66279A).
• A three positions header (CONN BOX) for providing the DC voltages for the optional connector
box.
• A five positions header (AC INPUT) for receiving the AC power input.***
• A three positions header (FUSE/SWITCH) for connecting the AC+ line to the fuse and switch
located on the front panel.
• A three positions header (AC OUTPUT) for providing the AC power to the power supply sub-
assembly (M45891).