Monopolar Control/Display
Cir
cuit Descriptions
Force 2 Service Manual
5
-
3
REM and RMOTE Indicators
The ICM7218C does not control the REM and RMOTE indicators.
Microcontroller port lines P12 and P16, buffered by U5B and U5A, drive
the REM and RMOTE indicators directly. Pull-up resistors R45 and R47
ensure that the outputs of the open collector driver pull high when its
inputs are low.
An additional circuit in parallel with the REM LED is transistor Q1, which
turns on when the REM indicator illuminates. This transistor shorts out
the volume control potentiometer causing the alarm tone to sound at full
volume.
Two digit drive lines and seven segment drive lines, bused from the
Monopolar Control/Display board to the Bipolar Display board, control
the bipolar display seven segment digits.
Integrated circuit U11C, configured as a single gate oscillator, R22, and
C26 serve as the principal frequency determining elements. R23 and CR8
change the duty cycle of the oscillator and help to fine tune the final audio
output. Port lines of the 89C54, P10 and P11, control the audio enable and
tone frequency respectively. These two control lines activate an on/off
analog switch which gates the audio drive signal to the audio amplifier
stage comprised of U5F and U5G. A second analog switch, when enabled,
increases the net capacitance of the audio oscillator timing elements,
thereby lowering the frequency. A filter consisting of R7 and C4 rolls off
the high frequency components of the audio signal reducing the harshness
of the audio tone. A large R-C filter, R19 and C20, on the power input to
U1, provides decoupling from the 5V supply.
RF Indicators
The display driver does not control the RF indicators. Port lines P24
through P27, buffered by U5D, U5C, and U5E, drive the Cut, Coag, and
Bipolar RF power indicators. Q5 further controls the indicators. For the RF
indicators to illuminate, the presence of either the LMPTST or RF_SENSE
signals must turn on this transistor.
When you turn on the generator, LMPTST performs a display test that
turns on all of the display digits and indicators. RF_SENSE, coming from
the PSRF board, activates whenever the ECON voltage reaches a level to
provide usable output.
The 89C54 communicates directly with the ICM7218C; that is, the display
driver is a device on the CPU's data bus. For the CPU to read from or write
to its peripherals, the system must generate chip selects external to the
CPU. The falling edge of the address latch enable (ALE) line on the CPU
indicates that a valid address is present on the data bus. A 74LS374 octal
D-type latch (U9) latches the external memory address of the selected
peripherals.
Summary of Contents for Force 2-2 PCH
Page 1: ...Service Manual Force 2 Electrosurgical Generator...
Page 10: ...Notes x Force 2 Service Manual...
Page 16: ...Notes 2 4 Force 2 Service Manual...
Page 32: ...Notes 4 10 Force 2 Service Manual...
Page 52: ...Typical Output Waveforms 6 12 Force 2 Service Manual Figure 6 5 Coag 300 Load...
