Covidien WarmTouch, Service Manual

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Troubleshooting
6-6 Service Manual
Power Supply
The power supply is located inside the front enclosure ( Figure 10-31 on
page 10-43). It is an internally-fused AC/DC converter delivering 48VDC, 65W
output from an input range of 90-264VAC. It has an input connection from
the AC power inlet, an output connection to the power PCBA, and a ground
connection to the equipotential stud. The 48V output from the power supply
is converted to 12V, 5V, 3.3V, and 2.5V on the power PCBA to drive various
system components.
HEPA Filter
The HEPA filter is located inside the filter enclosure at the back of the unit (see
Figure 5-3 on page 5-6). The fan draws air into the filter through the opening
at the base of the filter enclosure prior to delivering the air across the heating
element.
The filter must be replaced every 2,000 hours of operation or 365 days, which-
ever comes first. Software counters track the number of power-on hours and
calendar days since the previous filter change. These counters rely on the real-
time clock (RTC) located on the UI PCBA.
When the filter needs to be replaced based on either of the counters, the user
is notified at power-on. The counters can be reset using a key code at the
keypad when the filter is replaced.
Heater
The heater is located below the fan assembly inside the rear enclosure (see
Figure 11-40 on page 11-43). The heater consists of a wire-wound element
that generates heat when current (90-264VAC) is passed through it. The
heater connects to the power PCBA and is controlled by the A/D microproces-
sor based on user input and thermistor feedback.
Fan
The fan is located inside the rear enclosure (see Figure 11-30 on page 11-33).
It is powered by 48VDC from the power PCBA. Fan speed is monitored by the
A/D microprocessor and is voltage-controlled via circuitry on the PCBA. If the
speed is too low or too high, the software shuts down the fan and heater and
generates an alarm.