Run Mode; Output Mode Selection; Power Display - ConMed Hyfrecator 2000 Service Manual

3.3.4.1 Run Mode

Normal operation (Run Mode) occurs when the unit is powered up with the Service Jumper (A1J1) open-
circuited such that VCAL is greater than +3.75 Vdc. Entry to Run Mode is accompanied by execution of
the Power On Self Test cycle described in Section 3.3.5.3. After the POST cycle completes, the Power
display shows the last power setting for the selected Mode as it was read by the Control microcontroller
from its EEPROM. The operator may then change modes at will, and the most recent power setting used in
that mode will appear in the power display. The power setting for each mode is independently adjustable
using either the power control knob on the front panel or the up/down buttons on the handswitched
accessory. RF output may be activated by pressing the activation button on the handswitched accessory or
by closing the optional footswitch. Activation is accompanied by an audible tone and illumination of the
blue activation LED.

3.3.4.1.1 Output Mode Selection

The unit may be set to operate in the High Voltage (Hi), Bipolar (Bi) or Low Voltage (Lo) mode via the
Mode Selector switch, S1. S1 comprises a set of gold-plated pads on the solder side of the A1 PWB
which are selectively shorted together by a moving contact mounted on the Mode Selector mechanism
secured to the front panel.
Switch S1 drives a discrete digital-to-analog converter made up of R9, R10, R12 and R13. The analog
output signal, VMODE, assumes a DC voltage unique to each of the three positions of S1:
MODE VMODE
HI +0.75 to +1.75 V
BI +2.00 to +3.00 V
LO +3.25 to +4.25 V
VMODE is provided to both the Control and Monitor microcontrollers via isolation resistors as VMODE.C
and VMODE.M. The Control microcontroller uses VMODE.C to select the appropriate gate drive
waveform on /GATEPWM and to present that mode's power setting on the LEDs.
If Vmode falls outside of the 0.5V tolerance range, due to S1 being set to an intermediate position or a
component fault, the Control microcontroller will present "--" on the LED display, and activation is
inhibited.
The Monitor microcontroller uses VMODE.M to validate the gate drive and the mode data presented to it
by the Control microcontroller on the PSET bus. If the Monitor microcontroller disagrees with these
Control actions, a fault is declared.

3.3.4.1.2 Power Display

Power settings are presented on the two-digit numeric LED displays, X1 and X2, as Watts deliverable to the
rated load resistance for the selected mode (500 Ω for LO and BI, 1000 Ω for HI). The Control
microcontroller drives the segment data LED1:8 via current limiting resistor pack RN1 to X1 or X2 in
alternating fashion at a 100 Hz scan rate. The active common-cathode LED digit is selected by LED1S and
LED10S which drive Q1 and Q2, the digit drivers. Each digit is driven continuously for 4 msec followed
by a 1 msec blanking period before the other digit is selected.
2000
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