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Model 300E Carbon Monoxide Analyzer
Instruction Manual
TROUBLESHOOTING & REPAIR PROCEDURES
P/N 04288 REV: A
207
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If the unit is set for 230 VAC and is plugged into 115VAC, or 100VAC the
sample pump will not start, and the heaters will not come up to temperature.
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If the unit is set for 115 or 100 VAC and is plugged into a 230 VAC circuit,
the circuit breaker built into the ON/OFF Switch on the Front Panel will trip to
the OFF position immediately after power is switched on.
11.5.2.
DC Power Supply
If you have determined that the analyzer’s AC mains power is working, but the unit
is still not operating properly, there may be a problem with one of the instrument’s
switching power supplies. The supplies can have two faults, namely no DC output,
and noisy output.
To assist tracing DC Power Supply problems, the wiring used to connect the various
printed circuit assemblies and DC Powered components and the associated test
points on the Relay Board (03134) follow a standard color-coding scheme as
defined in Table 11-4.
Table 11-4: DC Power Test Point and Wiring Color Codes
Name
Test Point#
TP and Wire Color
Dgnd 1
Black
+5V 2
Red
Agnd 3
Green
+15V 4
Blue
-15V 5
Yellow
+12V 6
Purple
+12R 7
Orange
A Voltmeter should be used to verify that the DC voltages are correct per the values
in Table 11-5 below, and an oscilloscope, in AC mode, with band limiting turned on,
can be used to evaluate if the supplies are producing excessive noise (> 100 mV p-
p).
Table 11-5: DC Power Supply Acceptable Levels
Check Relay Board Test Points
From Test Point
To Test Point
Power
Supply
Assy
Voltage
Name # Name #
Min V
Max V
PS1 +5 Dgnd 1 +5 2 4.8
5.25
PS1 +15 Agnd 3 +15 4 13.5 16V
PS1 -15 Agnd 3 -15V 5 -14V
-16V
PS1 Agnd Agnd 3 Dgnd 1 -0.05 0.05
PS1 Chassis Dgnd 1 Chassis N/A -0.05 0.05
PS2 +12
+12V
Ret
6 +12V 7 11.75
12.5
PS2 Dgnd +12V
Ret 6 Dgnd 1 -0.05 0.05