FISCHER MD-1a, Техническое справочное руководство, Страница: 8 / 10

Electrical Device Inspection (Continued)
Period: Annually (12 months)
Device Output:
PRELIMINARY SETUP:
•
Plug line cord into a grounded receptacle and press the bottom edge of the POWER
switch to turn on the MD-1a (red portion of power switch will be visible). Note that the
red “ACTIVE” LED will NOT be lit unless a patient circuit is completed between the
Output Jacks and current is flowing.
•
Attach the dual patient cordset to the Output Jacks and make all measurements
between the red and black banana plugs at the end of the cordset using a series load
resistance of 1K ohm rated at 3 watts or more. (A 2 watt resistor may be used for
short duration measurements).
OUTPUT MEASUREMENTS :
◊
Measure Minimum output using a DC milliameter in series with a 1K load resistance
and Intensity control knob set to its minimum position. This measurement simply
confirms that there is no unintended output current with the Intensity knob at its
minimum (zero) position.
Accept: 0 DCma
◊
Measure Maximum output using a DC milliameter in series with a 1K load resistance
and Intensity control knob set to its maximum position. Note that the MD-1a can
produce approximately 50 DCma at this this setting, which will require a resistor rated
at 2.5 Watts or higher.
Accept: 40-58 DCma
◊
Verify meter reading on 0-10 scale. With a 1K load resistance, set the METER
SCALE switch to the 0-10 position and adjust Intensity until the the meter settles on a
reading of 10ma (full scale). Measure the actual current using a DC milliameter in
series with the load resistance.
Accept: 8.0-12 DCma
◊
Verify meter reading on 0-50 scale. With a 1K load resistance, set the METER
SCALE switch to the 0-50 position and adjust Intensity until the the meter settles on a
reading of 20ma. Measure the actual current using a DC milliameter in series with the
load resistance.
Accept: 16-24 DCma
NOTE: The MD-1a incorporates circuitry to slowly ramp the output current to its set value
when a load resistance is detected. Therefore, you must allow several seconds for the
output current to stabilize before making these measurements.
AC RIPPLE (OPTIONAL):
◊
Measure the AC ripple present in the output current by connecting an isolated ground
oscilloscope in parallel with the 1K load resistance. Adjust Intensity for a metered
output of 20 DCma (using 0-50 scale) and observe the AC component (ripple)
superimposed on the DC waveform.
Accept: 0-.5 Vpp (2.5%)
Note: Output specifications measured at 115VAC line voltage
DEVICE INSPECTION
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