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11. ANNUAL PREVENTIVE MAINTENANCE AND CALIBRATION
1.
Electronic callbratlon
&
checks
a. PProcessor Pcb: RTCC (real time clock circuit) 256.000 Hz check and calibration. Gold lithium battery
check (Vout
2
2.8 Vdc, nominal 3.7 Vdc).
b. ECG amplifier Pcb: +2 Vdc & -2Vdc reference Voltage calibration. PWM ramp time (4000 factor on the
TEST display).
f
5 Vdc supply of the DC/DC converter /Tolerance on both supply
=
200 mV). The on
board high voltage discharge protection bulb must be checked
(no
electrode contact !). Output fuses of
the scope & bad line (Ohmic test). Test of each High pass capacitor by applying
+
100 mV dc offset to
the input of the filter and pressing the reset key function (the offset line should be kept straight without
moving away). Functional test of the ECG Pcb with a real patient. Cable test function must be checked
with a good and a bad cable.
c. Power supply: every single supply must
be
measured by a D.V.M. (under bad), no adjustment only
check.
d. Printer timer \ Paper mark detection and stepper motor ad/check must be done. The printer timer 2nd
monoflop must be measured according to the printer head impedance and re-calibrated
if
needed
(Tolerance f 10 ps).
e. Battery charge voltage calibration & check
f. The battery capacity shall be tested in continuous Rhythm mode. The AT-6 shall work for at least
1 1/2 hrs (battery must be previously fully charged).
If
not, the 12 V battery shall be exchanged.
g. The battery protection fuse (2A, s.b) needs to be checked
h. Check on power supply MK2-6 (Batt. charge circuit) for square wave signal Vss 30V at 54 kHz (be-
tween 47 and
60
kHz)
j. The display contrast adjustment needs to be checked (from max..min).
2. Mechanical adj,
replacement
/ Test:
a. paper table: The paper table mbber cylinder Schiller P/N 4.410046 (including the cylinder bearing, P/N
4.410041) may
be exchanged after
1 Year of use (optional). The cylinder Nylon gear must be optically
checked and if needed exchanged. After exchanging the rubber cylinder and readjusting the printer
timer monoflop, the unit must show good printing results. If not, recheck with the lowest speed in
manual W e at 12 CH and activate the 1 mV function continuously.
b. Printer head readjustment (optional) only with weight gauge.
c. Photocell replacement and readjustment (PIN 3.900703)
d. Keyboard test (each key shall be depressed and correctly decoded)
3.
Accessories
The patient cable shall be thoroughly measured and tested incl. all peripheral connectors.
0-1 7
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