Cmrr Check; Checking Blocking; Checking Frequency Characteristic - Innomed Medical Heart Screen 60G Service Manual

Innomed Medical

6.5.3 CMRR check

For CMRR setting connect the patient cable and short all the electrodes except for the "N" point. Apply a 1Vpp +/-
0.5% amplitude 50Hz sine signal between the amplifier's ground point and the shorted electrodes. Set the device to the
highest, 0,5mV/cm sensitivity (x2) and 25 mm/sec speed. With the channel selector monitor all the channels one-by-
one.
During monitoring measure the signal on the AD input (AD1.5 pin) with a scope by synchronizing it to the CH3MPX
(U20.15) signal. The eight channels' phases must be visible on the scope. The individual phase's time is 125 Rsec.
During continuous monitoring try to decrease the error signal with P6-and resistor R176 so approximately the same
error signal is generated on all the channels. Watch the error signal on the scope.
The CMRR is acceptable is the measured amplitude is less than 250 RVpp, or 74 dB.
P1
N
N
N
N
N
N
N
N

6.5.4 Checking blocking

For the measurement connect the patient cable and short all the electrodes with the exception of the "R" lead. Apply
+320 mV DC voltage between the "R" lead and the other leads. Set the device to highest, 0.5mV/cm sensitivity (x2)
and 25 mm/sec speed.
Monitor all the channels one-by-one during continuous monitoring. During monitoring give a blocking command.
After blocking the signal must remain within 100 RV. Allow the signal to run for at least 10 seconds on all the
channels after blocking, the baseline must remain in the +/-100RV range all along.
Repeat the measurement with -320 mV DC as well.

6.5.5 Checking frequency characteristic

Apply (16000 +/-0.5% RVpp / 150Hz sine) + DC signal on the amplifier input according to the tables from a ground-
independent generator. DC should be +320, -320 mV. Set the device to 4mV/cm sensitivity (x1/4) and 25 mm/sec
speed.
Connect the patient cable according to the following tables, start the individual channels with the channel selector and
measure the signal amplitude.
a/ In case of DC = -320 mV
The signal's amplitude on the measured lead should be at least 11200RV.
P1
L
R
V1
V2
V3
V4
V5
V6
2014.01.09
Heart Screen 60G-80G-L
P2 Measured lead
all other I
all other II
all other V1
all other V2
all other V3
all other V4
all other V5
all other V6
P2 Measured lead
all other I
all other II
all other V1
all other V2
all other V3
all other V4
all other V5
all other V6
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Service manual