Dc Power Supply; I 2 C Bus - Teledyne T300 Operation Manual

Teledyne API – Model T300/T300M CO Analyzer

12.5.2. DC POWER SUPPLY

2
12.5.3. I C BUS
06864B DCN6314
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 the following table.
Table 12-6: DC Power Test Point and Wiring Color Codes
NAME TEST POINT#
Dgnd
+5V
Agnd
+15V
-15V
+12R
+12V
A voltmeter should be used to verify that the DC voltages are correct per the values in
the table 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 12-7: DC Power Supply Acceptable Levels
POWER
SUPPLY VOLTAGE
ASSY
PS1 +5
PS1 +15
PS1 -15
PS1 Agnd
PS1 Chassis
PS2 +12
PS2 Dgnd
2
Operation of the I C bus can be verified by observing the behavior of D1 on the relay
PCA. Assuming that the DC power supplies are operating properly, the I
operating properly if D1 on the relay PCA is flashing.
TP AND WIRE COLOR
1 Black
2 Red
3 Green
4 Blue
5 Yellow
6 Purple
7 Orange
CHECK RELAY BOARD TEST POINTS
FROM TEST POINT
NAME #
Dgnd 1
Agnd 3
Agnd 3
Agnd 3
Dgnd 1
+12V Ret 6
+12V Ret 6
Troubleshooting and Service
TO TEST POINT MIN V
NAME #
+5 2 4.8
+15 4 13.5
-15V 5 -14V
Dgnd 1 -0.05
Chassis N/A -0.05
+12V 7 11.75
Dgnd 1 -0.05
MAX V
5.25
16V
-16V
0.05
0.05
12.5
0.05
2
C bus is
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