Table of Contents
Advertisement
If the square wave (from any of the request sense circuits) is not present at the system logic when the unit is initially
turned on, the system displays an error code, sounds an alarm, and disables RF output.
Temperature Sensing Circuits (3)
The Temperature Sensing Circuits are used by the control circuit to monitor the internal temperature of the unit.
These sensors are used as thermal protection for the unit. If the internal temperature of the unit is too high an
error code is displayed.
Neutral Electrode Monitoring Circuit (NEM)
The Bovie NEM™ is a quality monitoring circuit that detects the type of return electrode (solid or split).
The circuit also continually monitors the contact quality between the patient and the split return electrode.
This helps to eliminate patient burns at the return electrode site.
When you connect a single return electrode to the unit, the NEM will detect if the resistance is below 5 Ω. If it is,
the 2250 will display the green single plate LED on the front of the unit.
When you connect a split return electrode to a patient, and the NEM detects a resistance between 10 and 135 Ω,
then the 2250 will display the green split plate LED on the front of the unit.
The NEM constantly monitors the patient contact quality. If the impedance changes by a specific amount, then the
unit will display an alarm, and immediately de-activate the RF output power.
Footswitch Sensor Circuits (2)
The Footswitch Sensor Circuits are used to determine the presence or absence of the monopolar and bipolar
footswitch. The footswitch sensors circuits are made up of a Colpitts Oscillator (operating at approximately 50 kHz)
and a level detection circuit.
In a non-activation status, the Colpitts Oscillator operates at its set operating frequency, and presents a sine wave to
the level detection circuit. The level detection circuit converts the sine wave into a square wave. Activation will not
occur as long as a square wave is present.
When a resistance (approximately 200 W or less) is presented to the transformer's secondary winding by a hand-
control or foot-control, the sense transformer is essentially shorted. The "short" is felt on the transformer's primary
winding causing the Colpitts Oscillator to temporarily shut down.
When the oscillator shuts down, the sense signal becomes +5 VDC (logic "1"). This informs the system logic that a
handswitch or footswitch activation request has been made.
If the square wave (from any of the request sense circuits) is not present at the system logic when the unit is initially
turned on, an error code is displayed, an alarm sounds, and the RF output is disabled.
Input Voltage
The Aaron 2250 is designed to operate at a wide range of input voltages. The unit will perform with in
specifications with an input voltage within the range of 100-240VAC 50/60 Hz. The input voltage is connected
via a power entry module. The power entry module is a medical grade filter to minimize leakage currents,
radiated emissions, and conducted emissions.
Display Control Circuits
The Display Control Circuits are used to control all of the segment displays and LEDs used on the front panel.
Ser vice Guide • Aaron
4-3
Advertisement
Table of Contents
Troubleshooting
