Checking Voltages - Ecg Side; Ecg Part Test; Offset Measurement; Amplification Setting And Dc Tolerance Measurement - Innomed Medical Heart Screen 60G Service Manual

Innomed Medical
6.4 Checking voltages – ECG side
Turn on the device, running from 9V (battery voltage). Connect short on the ECG input. For ECG side measurements
the GND TP7.1 is the short.
Measurement point
TP7.2
(D46 cathode
+VCCAN)
TP7.3
(D47 anode
-VCCAN)
TP7.6
(AD1.10)
TP7.4
J11.5
J11.12
JP1.2
6.5

ECG part test

6.5.1 Offset measurement

To set the offset, connect the patient cable and short all the electrodes. Set the device to maximum sensitivity (x2) and
25 mm/sec speed. Start continuous monitoring and give a BLOCK command.
Step the lead selector over the I, II, V2...V6 leads and measure the zero line. Find the channels with the greatest
positive and negative offsets. The measured offsets are +DCmax and -DCmax. Using the P20 potential meter set the
offset so the
|+DCmax| - |-DCmax| = 0 equation holds true.
The tolerance may be +/- 100 RV at most, which means 2mm on the printout at 2x sensitivity.

6.5.2 Amplification setting and DC tolerance measurement

Apply (16000 +/-0.5% RVpp / 10Hz sine) + DC signal on the amplifier input according to the tables from a ground-
independent generator. DC size should be 0, +320, -320 mV.
Set the device to 2 mV/cm sensitivity (x1/2) and 25 mm/sec speed. With the lead selector start all the channels and
measure the signal amplitude.
Select the largest and smallest amplified channels, and have the measured amplitudes be Umax and Umin. Set the
amplification with the R155 and R157 resistors so the
(Umax – Umin) / 2 = 16000 CV+/-80CV (+/-0,5%) equation holds true.
After the amplification setting perform the following checks.
2014.01.09
Heart Screen 60G-80G-L
Nominal value
+7V
-7V
2.048V
+5V
Data signals with 4
Ksec clock signal
4 Ksec clock signal
with 50% divide ratio
Max. 210 mA
Tolerance Comment
+/-0.3V
The analog power is to be set with
P14, in case of raw setting, use R51.
+/-0.3V
+/-5 mV (!) Reference, set with P8 (on digital
side!)
+/-0.15V Digital power on the ECG side.
+/-0.2 Ksec Check data signals
16 / packet, repeating time 250 Ksec.
(due to the 500Hz PIC!)
+/-10% Check (if necessary, set with R78)
divide
Battery consumption (when SIO
turned on / marked with an * / 260mA)
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Service manual