11
If the last two steps are not as stated then
most likely the CPU board is bad and it will
have to be replaced.
-Switch the voltmeter to an "AC Volts" scale
capable of reading 120 Volts.
-Measure the voltage between U1-Pin 4 and
U1-Pin 6. It should be less than 1 VAC.
If it is not, most likely the optoisolator is bad
and the power supply board will have to be
replaced.
-Measure the voltage between TB1-4 (Orange
wire) and TB1-6 (Red wire). It should be line
voltage. 110 VAC to 120 VAC.
If it is not, then most likely the triac is bad.
The power supply board will have to be
replaced.
D) Measure RTD temperature probe resistance
at the connector after unplugging it from plug
J302. The resistance between contacts, at
various temperatures are as follows:
TEMPERATURE
RESISTANCE
0°C
100 OHMS
20°C
108 OHMS
37°C
114 OHMS
50°C
119 OHMS
NOTE
ONLY 2 OF THE 3 CONNECTORS POSITIONS ARE
USED.
4.
Malfunctioning RTD Temperature probe:
The Control Board can detect if the
temperature probe or the connection of the
temperature probe to the circuit board is
"OPEN" or "SHORTED". These two
conditions are shown on the display as
follows:
DISPLAY
CONDITION
OPEN CIRCUIT
SHORT CIRCUIT
Before coming to the conclusion that the probe
is bad when one of these displays appear,
check the connection of the probe to the circuit
board.
5.
RTD Temperature Sensor Probe Location:
The Proper RTD location is important. The
RTD is supported by the stainless steel
bracket attached on the rear wall and near
the top of the chamber. Two tube shaped clips
securely support the RTD probe into place.
The RTD must be inserted fully into its support
bracket.
6. Constantly Experiencing Low temperature
Alarm:
If the incubator is constantly going into low
temperature alarm, then most likely the
setpoint temperature setting is too close to the
low temperature alarm/setpoint setting. The
setpoint temperature setting should be a
minimum of 2° above the low temperature
alarm setting. If the problem persists, then see
Remedy 3.
7.
Constantly experiencing high temperature
alarm:
If the incubator is constantly going into high
temperature alarm, then most likely the
setpoint temperature setting is too close to the
high temperature alarm/setpoint setting. The
setpoint temperature setting should be a
minimum of 2° below the high temperature
alarm setting. If the problem persists, then see
Remedy 3.
NOTE
SOFTWARE VERSION 2.00 HAS A 30-MINUTE
DELAY FOR THE LOW AND HIGH ALARM TO AVOID
NUISANCE ALARMS CAUSED BY DOOR
OPENINGS.
8. Ice buildup on evaporator coils:
Excessive frost buildup is the result of the
introduction of outside moisture. This may be
caused by the evaporation of liquids placed
in the chamber, or it may be the result of
excessive opening of the door during high
humidity conditions. The door gasket should
also be examined for proper seal; if repairs
are necessary, contact Thermo or adjust door
hinges.
