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Model 400E Ozone Analyzer
Instruction Manual
11.5.3. I
2
C Bus
Operation of the I
Relay Board in conjunction with the performance of the front panel display.
Assuming that the DC power supplies are operating properly and the wiring from
the Motherboard to the Keyboard, and the wiring from the keyboard to the Relay
board, is intact, the I
•
D1 on the relay board is flashing, or
•
D1 is not flashing but pressing a key on the front panel results in a change to
the display.
11.5.4. Keyboard/Display Interface
The front panel keyboard, display and Keyboard Display Interface PCA can be
verified by observing the operation of the display when power is applied to the
instrument and when a key is pressed on the front panel. Assuming that there are
no wiring problems and that the DC power supplies are operating properly:
•
The vacuum fluorescent display is good if on power-up a "-" character is visible
on the upper left hand corner of the display.
•
If there is a "-" character on the display at power-up and D1 on the Relay Board
is flashing then the Keyboard/Display Interface PCA is bad.
•
If the analyzer starts operation with a normal display but pressing a key on the
front panel does not change the display, then there are three possible problems.
1. One or more of the keys is bad,
2. The interrupt signal between the Keyboard Display interface and the
motherboard is broken, or
3. The Keyboard Display Interface PCA is bad.
11.5.5. Relay Board
The Relay Board PCA can be most easily checked by observing the condition of the
its status LEDs on the Relay Board, as described in Section 11.1.4.1, and the
associated output when toggled on and off through SIGNAL I/O function in the
DIAG menu, see Section 11.1.3.
•
If the front panel display responds to key presses and D1 on the Relay Board is
NOT flashing then either the wiring between the Keyboard and the Relay Board
is bad, or the Relay Board is bad.
P/N 04316 Rev: B
2
C bus can be verified by observing the behavior of D1 on the
2
C bus is operating properly if:
TROUBLESHOOTING & REPAIR PROCEDURES
259
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