Datex-Ohmeda CAPNOMAC ULTIMA, Service Manual

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CAPNOMAC ULTIMA
TM
SERVICE MANUAL
5-35
5.8 Power supply board
Block diagram and transformer diagram
Signal waveforms and schematic diagram part 1
Parts layout and schematic diagram part 2
Schematic diagram part 3
Figure 5.20
Figure 5.21
Figure 5.22
Figure 5.22a
Principle of operation
The primary of the power supply is designed to double insulation
requirements for added safety. Depending on model there is either
one (l00-120 V countries) or two (220-240 V countries) fuses. The
primary operating voltage is factory selected by insulating and
folding the unused primary leads inside the additional insulation
tube.
The mains transformer is magnetically shielded to minimize screen
disturbance.
The power supply board contains basically four DC sources:
- + 5 V switched, for digital circuitry and ACX measuring unit
- + 15 V switched, for motors, pumps and other components.
- +/-15 V for analog amplifiers.
Data retention voltage generation circuit su5 V DRV
voltage for memory from sw5 V supply.
Also, +12 V/l A for the CRT unit and serial drivers/receivers is
derived from the +15 V switched voltage. The -12 V for the serial
I/O is derived from -15 V.
The +5 V for the infrared lamp is controlled by the ACX
measuring board via the LAMP ON signal, which cuts the lamp
power in case of a stalled optical chopper wheel or a missing
timing signal.
The gas sampling pump is driven by a 50 Hz/15 V/0.4 A square
wave signal generated by the CPU.
In addition to the power supply functions the board contains
drivers for two serial channels (including the modem control
signals CTS and RTS), a RESET control, which generates a 200 ms
reset pulse to the CPU if the +5 V line goes below 4.75 V, and
miscellaneous I/O functions like a buzzer driver. Some signals from
the mother board are passed directly to the rear panel connectors.
January 15th, 1997/6