Switch the chart recorder mode selector to DELAYED.
(6) Adjust R141 until the signal amplitude on the chart recorder and the CRT
are similar in amplitude. Remember that the signal recorded on the chart is always five
seconds delayed with respect to the CRT display in this mode of operation.
e. Calibrate and Check the Quasi-Random Signal Sensitivity Sensitivity.
Refer to Appendix B, Monitor Board Analog Schematic, section D-8.
(1) Turn down the output of the ECG simulator to 0.4mv, 60bpm, Lead 1
(2) Adjust R145 (one-turn control) to a point where the system just recognizes
a QRS complex.
Now switch the ECG simulator to 5.0mv output.
Reduce the size to 20mm. No double triggering should be noticeable.
(5) Switch the amplitude back to 1.0mv and the rate to 240bpm. No beats
should be missing.
Now lower the rate to 30bpm. The recognition should be correct.
f. Check the Overall Signal to Noise.
Operate the unit in Lead 1. Allow a few minutes for stabilization.
(2) Apply a 20 microvolt signal from the output of the ECG simulator to the
patient cable input. The heart rate should be 60bpm. The QRS complexes should still be
recognizable as little bumps about twice in size than the width of the base line trace.
g. Check the Synchronizer.
(1) You can make this check with or without the defibrillator connected and
turned ON (not charged up and sync switch engaged). A marker pulse should appear on
the CRT screen each time a QRS complex appears at the patient cable input.
(2) Switch to paddle pick-up, and the marker pulse is canceled out, even if a
QRS signal is applied to the paddles.