ConMed sabre 180, Руководство по обслуживанию

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4-15
Check the Base Voltage Generator and Waveform
Generator for proper function before proceeding.
If everything checks this far, enter dI2 (see
Section 4.5.2) and select Pure Cut from the front
panel. Confirm that A4TP9 has approximately 0
to 10V signal swings, and the same shape as
A3TP10.
Turn off the power to the unit and replace the
base fuses. Reenter dI2 and select Pure Cut from
the front panel. Use an oscilloscope on the drain
of A4Q2 to confirm that the power MOSFET is
switching properly.
If the unit has passed all tests to this point, it will
be necessary to replace the collector fuses to trou-
bleshoot further. Proceed with caution!
Observe instructions for heatsink mounted device
replacement in Section 5.2.3.
4.5.7 Continuity Detector Troubleshooting
If the symptom is a HLP -8, stuck control switch,
first ensure that the hand or foot switch was not
accidentally closed by the user during power-up.
Otherwise, isolate the problem by powering up
with those accessories disconnected. If the symp-
toms persist, disconnect A4P5 and P6 to isolate
the trouble to the A4 or A3 PWBs. The most
likely culprit on the A3 PWB is A3U11.
Otherwise, the trouble is in one of the four iden-
tical isolation circuits or one of the ribbon har-
nesses.
If the symptom is Failure to Activate, first verify
that the hand or foot accessory is functional using
a ohmmeter. Contact resistance must be below
about 300 ohms to operate this unit.
Troubleshooting the unit should begin by deter-
mining if all or only one the four isolation circuits
is malfunctioning. This is easily determined while
the unit is still in service by operating both hand
and foot switch cut an coag switches and observ-
ing the unit's response. If the unit's response is
normal, verify RF output.
If only one of the accessory lines exhibits trouble,
and the others are OK, then the problem is likely
to be isolated to its associated circuitry. Fault iso-
lation may proceed most expediently by compar-
ing voltages in the faulty circuit to those in an
operational one.
The open circuit voltage on the switching lines
should be about +2.7Vdc relative to the common
switch line. If all four fail to cause the unit to
respond, or the sense voltage is low, then the
trouble is likely to be in the isolated power sup-
ply, A4U2 and Q10.
Use an oscilloscope to check Q10-D and U2-3
against Figure 3.3. If the waveforms and frequen-
cy appear correct, check for intermittents by mov-
ing the associated components with an insulated
rod. If the Q10-D waveform deviates significantly
from a half-sine, check for C43 open circuited or
a shorted rectifier, D10 or D11, or shorted capac-
itor, C65 or C66. A broken ferrite core on T2
will also show this symptom. If the voltage on
Q10-D is near zero, Q10 may be shorted, which
will also pull the +12V supply down. If the fre-
quency deviates significantly from 90 KHz, check
the values of timing components R30, 31 and
C22; if these appear OK, then replace U2.
If one of the handswitched optoisolators is
replaced, its body should be covered in clear, self-
bonding heatshrink to retain clearances required
by IEC 601.
After repairs, verify that all switch inputs are
functional, and that none of them respond with
switch resistances over 1000 ohms. Verify that the
FRET and H1RF lines remain isolated from
ground.
4.5.8 RF Power Supply Troubleshooting
Turn power off first and remove all base fuses
(F1-F3) and collector fuses (F4-F6). Then dis-
connect P2 and P6 from A4 to isolate the power
supply circuitry from the system. Inspect mains
fuses (A6 F1 & F2) to see if they are blown. Use
a DMM to check the circuit connections and
parts on the board, especially the power FET Q1,
diode CR1, and capacitor C2. Replace bad com-
ponents and fix open and short circuits if neces-
sary.
Turn power on and measure the voltages at
RFSUP (TP15, 68-76V), +17V (U1-15, 16-
19V), +7.5VREF (U1-9, 7.2-7.8V), and
PFCEN (TP14, 5.0-6.0V) with a DMM. With
PFCEN shorted to GROUND, the RFSUP
voltage should be read as follows: