Fukuda Denshi HS-8000 Series Service Manual Download Page 51

Page: 51 / 132

－

Multi AMP Board Circuit Explanation

Measurable parameter

According to the type of cable, BP, TEMP, CO can be measured.

Parameter Switch

Reference voltage is generated toward the Multiparameter input connector and resistance mounted
in the connected relay cable and the voltage divided by the reference resistance are received by
the buffer amplifier.Received electric potential is converted into A/D by the A/D converter, the
software reads the A/D value, and then the type of each relay cable is detected.

BP Measuring Circuit

The 5

V/mmHg/V Transducer can be used.The circuit is amplified in the first differential amplifier,

and further amplified in the second amplifier.Then the circuit is converted into A/D by the A/D
converter. The data converted into A/D performe waveform filtering process and calculation of
measuring value in CPU, isolated in photo coupler, and transferred to the CPU board.

TEMP Measuring Circuit

TEMP Measurement
TEMP measurement matches YSI-400 series Thermistor only.
In TEMP measuring circuit, reference voltage for measurement. TEMP signal, GND level (Zero
electric potential) are multiplexed and inputted into the A/D converter. During measurement, signal
calibration is performed on a steady basis.
The data converted into A/D performe filtering process and calculation of measuring value in CPU,
isolated in photo coupler, and transferred to the CPU board.

YSI-700 Detection
YS-700 is detected by distinguishing the difference between YSI-700 series Thermistor which has
3-electrode plug and YSI-400 series Thermistor which has 2-electrode plug. If there is the potential
difference in 2 terminals which should be in the same electric potential in YSI-400 series, the
terminals are detected as YSI-700.

CO assigns Multiparameter Amplifier Ch1 to Blood Temperature and Ch2 to Injectate Temperature.

Blood Temperature Measurement
Blood Temperature is measured by applying excitation voltage to

Swan-Ganz catheter and

converting temperature change of

Thermistor resistance value in

catheter into voltage.

The

Swan-Ganz catheter is equipped with built-in reference resistance and the reference resistance and

thermistor resistance divides excitation voltage. Divided signal is multiplexed with excitation voltage
for measurement and GND level (Zero electric potential) as blood temperature signal and inputted
into A/D converter. The data converted into A/D is performed filtering process and calculation of
measuring value in Multiamplifier CPU, isolated in photo coupler, and transferred to the CPU board.

Injectate Temperature (In-line Sensor)
In Injectate Temperature, excitation voltage is divided by reference voltage and Thermistor voltage.
Subsequent process is the same as Blood Temperature Measurement.

Injectate Temperature (Injectate Probe)
Excitation voltage is divided by reference voltage and Thermistor voltage.
Subsequent process is the same as Blood Temperature Measurement.