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Troubleshooting & Service T400 Ozone Analyzer Operator’s Manual
260
TP1 TP2 TP3 TP4 TP5 TP6 TP7
DGND +5V AGND +15V -15V +12R 12V
Figure 12-4: Location of DC Power Test Points on Relay PCA
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
VOLTAGE
CHECK
RELAY BOARD TEST POINTS
MIN V MAX V
FROM
Test Point
TO
Test Point
POWE
R
SUPPL
Y
NAME # NAME #
PS1 +5 DGND 1 +5 2 +4.80 +5.25
PS1 +15 AGND 3 +15 4 +13.5 +16.0
PS1 -15 AGND 3 -15V 5 -14.0 -16.0
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 +11.8 +12.5
PS2 DGND +12V Ret 6 DGND 1 -0.05 +0.05
12.7.3. I
2
C BUS
Operation of the I
2
C bus can be verified by observing the behavior of D1 on the relay
PCA & D2 on the valve driver PCA in conjunction with the performance of the front
panel display.
Assuming that the DC power supplies are operating properly the I
2
C bus is operating
properly if:
If D1 on the relay PCA and is flashing, or
Pressing a button on the front panel results in a change to the display.
There is a problem with the I
2
C bus if D1 on the relay PCA is ON/OFF constantly and
pressing a button on the touchscreen DOES NOT results in a change to the display.
If the touchscreen interface is working but either the Watchdog LED is not flashing, the
problem may be a wiring issue between the board and the motherboard.
06870C DCN6332