Page 5.10
SCHILLER AT-2plus 6-Channel ECG Unit
SERVICE HANDBOOK Issue d May 2002
Chapter 5
Adjustments
Service Screen
The service screen provides information of the patient cable and electrodes and gives the value of
certain reference voltages and important internal offset values. These values are for information
only. The service screen also gives variable settings and measurements that can be set by the
service engineer; to carry out these adjustments some of the settings require additional test
equipment. To call up the service screen, make sure that the patient cable is connected and press
the following key sequence:
ALT - 0 - 3 - any number 0...6
To obtain a printout press P.
ECG Reference Voltage
This provides measurements and setting facilities for the
reference voltage used for accurate measurement of ECG
signals
• Uref +
This gives the value of the reference voltage
used in the multiplexer circuit on the ECG
Amplifier. The value of the reference
voltage is 2000 mV ±20 mV.
• Uref -
This is a negative reference voltage used
on the ECG Amplifier board. The value of
this voltage should be -2000 mV ±20 mV.
• Udif
This is the sum of the two reference values
above (Uref +and Uref -). This value must
be 4000 mV ± 20 mV.
• Uoff
This is the value of offset voltage on the
multiplexer circuit. This value should be in
the range ± 150mV
• Calib
This value is the Udif value divided by 4.
The nominal value is 1000 ±5 mV.
