GE 001C 051D 003A, Service Manual

Page: 38 / 282

Equipment overview: Theory of operation
2-18 Dash 3000/4000/5000 2000966-542D
Power supply
The subsystems within the patient monitor operate from a common 9 to
18 V power bus. Due to the wide variety of voltages required by the
various subsystems, power is converted locally by each subsystem. This
architecture results in an efficient and compact system by reducing the
number of conversions required and optimizing the physical size of each
converter for the specific application.
When operating on AC mains power, the power bus voltage is 18 V,
generated by the offline switching power supply.
No AC mains power switch is provided.
The line voltage range switch must be set to select 115 V or 230 V (90 to
132 VAC or 190 to 264 VAC, respectively).
Data Acquisition System (DAS)
All interfaces to the patient occur through the DAS. The ECG function
uses a direct connection to the patient; therefore it is separately isolated
from the other functions (except respiration, which shares the ECG
patient interface) to substantially reduce coupling of noise and leakage
currents to/from other functions. All remaining DAS functions (e.g.,
pulse oximetry, NBP, invasive pressure, temperature, cardiac output,
and CO
2
) share a common isolation barrier.
NOTE
The patient monitor supports three SPO2 configurations, Generic
Ohmeda SPO2, Masimo SET SPO2, and Nellcor OxiMax SPO2.