Page 5.9
Chapter 5
Adjustments
SCHILLER AT-2plus 6-Channel ECG Unit
SERVICE HANDBOOK Issue 1 June 1998
ECG Amplifier reference voltage
Switch the unit on and measure the voltage difference between the +2V reference and the -
2V reference on pins 1 and 7 of operational amplifier U5. Adjust trimmer VR2 to achieve a
voltage difference of 4000 mV ±2mV.
Obtain a printout of the test screen by pressing
ALT - 0 - 3 - any number 0...6
Ensure that the Uref+ and the Uref- measurements are both 2000mV ± 20mV. Ensure that
the Udiff reading is 4000mV . Adjust VR3 to achieve a Udif reading of 4000mV + 20mV.
Reassemble the unit as detailed in Chapter 4. Re-check the voltage by again obtaining a
service printout.
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