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TROUBLESHOOTING & REPAIR PROCEDURES
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 follow a standard color-coding scheme as defined in
Table 11-3.
Table 11-3: DC Power Test Point and Wiring Color Codes
A Voltmeter should be used to verify that the DC voltages are correct per the values
in 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).
Power
Supply
Assy
PS1
PS1
PS1
PS1
PS1
PS2
PS2
258
Name
Test Point#
Dgnd
+5V
Agnd
+15V
-15V
+12V
+12R
Table 11-4: DC Power Supply Acceptable Levels
CHECK Relay Board Test Points
From Test
Voltage
Point
Name
+5
Dgnd
+15
Agnd
-15
Agnd
Agnd
Agnd
Chassis
Dgnd
+12
+12V Ret
Dgnd
+12V Ret
TP and Wire Color
1
Black
2
Red
3
Green
4
Blue
5
Yellow
6
Purple
7
Orange
To Test Point
#
Name
#
1
+5
3
+15
3
-15V
3
Dgnd
1
Chassis
N/A
6
+12V
6
Dgnd
Model 400E Ozone Analyzer
Instruction Manual
Min V
Max V
2
4.8
5.25
4
13.5
16V
5
-14V
-16V
1
-0.05
0.05
-0.05
0.05
7
11.75
12.5
1
-0.05
0.05
P/N 04316 Rev: B
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