GE Eagle 1000, Servicing Instructions

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GE Medical Systems EAGLE 1000
Page 31
Information Technologies
Servicing Instructions 227 468 01 Rev. G
Otherwise, the system is switched on and off with the appropriate button on the front pa-
nel, which, just like the 10V comparator, exerts an effect via the processor on the ON/OFF
interface with its FET switch.
A 5V analog v5VREF is generated with a linear controller from the battery voltage
supplied when it is switched on. A switching controller generates the 5V digital voltage
from the battery voltage supplied when it is switched on. Apart from this the battery voltage
supply is used directly and unregulated for oscillators and other components requiring a
power supply.
2.2.4 Floating system power supply and signal flow
Power supply
see diagram “Floating system supply and signal flow”
The floating system is supplied from a central 100-kHz oscillator on the PCB ECG Moni
tor. This delivers the supply voltage stabilized on a HF transformer, i.e., individual power
fluctuations on some PCBs are not fully compensated. The individual floating components
receive power via the primary HF transformers connected in parallel. Isolation is effected
in these floating transformers. These each generate ±7.5V ±5%. In turn, in each case a
5V ±2% analog/digital voltage is obtained from these voltages.
Signal flow
see diagram “Floating system supply and signal flow”.
Apart from the non-invasive blood pressure all patient input circuits are high-impedance-
floating circuits. In terms of signals, these are isolated in both directions via optoelec-
tronic couplers. All other circuit components are not isolated and referred to circuit zero.
Furthermore, there is a separate ground contact to enable potential equalization.
The non-invasive blood pressure input is isolated by means of a non-electronic patient
input.
2.2.5 Signal exchange with the processor
see “Processor block diagram”
The processor on the PCB ECG Monitor comprises a controller with a separate 32kHz
quartz crystal, watch dog, RAM and EPROM. The controller is in communication with all of
the following units.