Troubleshooting - Thermo Scientific Precision 280 Installation And Operation Manual

Microprocessor-controlled general purpose water baths
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9.0

TROUBLESHOOTING

WARNING
SERVICE SHOULD BE PERFORMED BY A QUALIFIED
TECHNICIAN.
BEFORE
ELECTRICAL OR MECHANICAL COMPONENTS,
UNPLUG THE LINE CORD. IF ELECTRICAL POWER
IS REQUIRED FOR SERVICE, USE EXTREME CARE.
9.01 Refer to Troubleshooting Procedures Table
(9.03 through 9.06) for troubleshooting
information on the baths. This table provides
the basic information required to repair the
bath.
Problem
9.03 No Heat
REPLACING
ANY
Troubleshooting Procedures
1.
Verify that setpoint temperature is greater than the actual
water temperature.
2.
Check temperature probe.
A. Disconnect unit from electrical supply.
B. Disconnect temperature probe connector J5 from Control
Board.
C. Place 5 volt DC between Pins 1 & 3 on temperature probe
connector.
D. Place a voltmeter between Pins 2 & 3 on temperature
probe connector. Place the temperature probe in a bath
of known temperature. Verify that the output voltage of
the temperature probe approximately corresponds to the
values in the table below.
Degrees Centigrade vs. Output Voltage of Temperature
Probe
Temp °C
0
10
20
30
40
50
9.02 The following is a list of the tools and
instruments required to perform the
procedures outlined in the Troubleshooting
Procedures table.
Suggested Tools:
Phillips Screwdriver
7/16" Socket or adjustable wrench
Ohmmeter
DC Voltmeter
AC Voltmeter
5VDC Power Supply
Nut Driver 11/32"
Vout
Temp °C
320mV
60
500mV
70
680mV
80
860mV
90
1.040V
99.9
1.220V
7
Procedure
Vout
1.400V
1.580V
1.760V
1.940V
2.218V

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