CALIBRATE THE PADDLE PREAMPLIFIER
The only calibration necessary is to adjust the CMMR. Perform the following
procedures to calibrate the paddle preamplifier.
a. Adjust the CMMR. Refer to Appendix H, Porta Pak 90 Defibrillator Schematic,
(1) Turn on the defibrillator's power switch. Do not charge. The test is to be
performed on battery power.
(2) Connect the low output post of the generator to ground of the board (a
output goes to both paddles connected in parallel.
Connect the audio millivolt meter or a sensitive oscilloscope probe to pin 5
(5) Through the corresponding hole in the shield, insert a small screwdriver
and turn R180 so as to obtain the smallest possible output signal.
(6) Now change the input frequency to 60.0Hz (50.0Hz for 50Hz power line)
and turn the trimmer capacitor C97 until minimum signal condition is reached again. This
adjustment is critical. You may find it necessary to retrim R180 slightly and return to C97 if
the unit was badly out of calibration.
b. Check the Signal Gain. Refer to Appendix H, Porta Pak 90 Defibrillator
Schematic, section B-17.
(1) Connect a heart wave signal simulator with an output of 1mv from RA and
LA to each paddle.
(2) The signal amplitude at pin 5 of J11 should be in the order of 0.5v per mv
of input signal or greater.
The CMMR of the paddle preamplifier should be checked periodically.