Bovie Aaron 1250, Руководство по обслуживанию, Страница: 39 / 68

DC Supply Check Circuit
The DC Supply Check Circuit is used by system logic to monitor the high voltage DC supply. If the voltage
increases by 30%, the system displays error code E4 and disables the RF output.
For isolation purposes, the High Voltage Sense Voltage is measured from the 15-volt DC power supply.
Temperature Sensing Circuit
The temperature sensing circuit is used by the system logic to monitor the internal temperature of the unit. If the
temperature rises above 85° C, the system displays error code E7 and disables the RF output.
Four Request Activation Sensing Circuits
The Activation Request Sensing Circuit is used by the system logic to detect both hand controlled activation and foot-
controlled activation requests. This circuit is 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-con-
trol or foot-control, the sense transformer is essentially shorted. The "short" is felt on the transformer’s primary wind-
ing causing the Colpitts Oscillator to temporarily shut down.
When the oscillator shuts down, the sense signal b5 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.
Speaker Circuit
The audio circuit is used by the system logic to generate activation tones and alarm tones. Volume for the activation
tones may be adjusted from the back panel of the unit.
NOTICE
Alarm volume cannot be adjusted up or down.
Patient Return Electrode Sensing Circuit
The Patient Return Electrode Sensing Module senses and sends signals to the system logic that displays which type of
patient return electrode is attached to the patient.
When you connect a single plate patient return electrode to the unit, the Pad Sensing Module will detect if the resist-
ance is below 5
Ω . If it is, the Aaron 1250 will display the green single plate LED on the front of the unit.
When you connect a split plate patient return electrode to a patient, and the Pad Sensing Module detects a resistance
between 10 and 135
Ω , then the Aaron 1250 will display the green split plate LED on the front of the unit.
The Pad Sensing Module 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.
WARNING
Patient Return Electrode contact quality is only monitored when a split plate patient return
electrode is attached to the patient.
39 Ser vice Guide • Aaron 1250