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Troubleshooting & Service Model T101 Instruction Manual
228
9.5.5. I
2
C BUS
Operation of the I
2
C bus can be verified by observing the behavior of the LED labeled
D1 on the 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 as well as from the keyboard to the relay board is intact,
the I
2
C bus is operating properly if:
D1 on the relay board is flashing or;
D1 is not flashing but pressing a button on the touchscreen results in a
change to the display.
If the display is locked up or if the analyzer is not booting up at all, the I
2
C bus may be
the cause. Contact Technical Support if you suspect a problem with the I
2
C bus.
9.5.6. TOUCHSCREEN INTERFACE
Verify the functioning of the touch screen by observing the display when pressing a
touch-screen control button. Assuming that there are no wiring problems and that the
DC power supplies are operating properly, but pressing a control button on the touch
screen does not change the display, any of the following may be the problem:
The touch-screen controller may be malfunctioning
The internal USB bus may be malfunctioning
9.5.7. LCD DISPLAY MODULE
Verify the functioning of the front panel display by observing it when power is applied
to the instrument. Assuming that there are no wiring problems and that the DC power
supplies are operating properly, the display screen should light and show the splash
screen and other indications of its state as the CPU goes through its initialization
process.
9.5.8. RELAY BOARD
The relay board circuit can most easily be checked by observing the condition of its
status LEDs as described in Section 10.4.9, and the associated output when toggled on
and off thro
ugh the SIGNAL I/O function in the DIAG menu, see Section 4.6.1.
If the front
panel display responds to key presses and D1 on the relay board is not
flashing, then either the I2c connection between the motherboard and the relay board is
bad, or the relay board itself is bad.
If D1 on the relay board is flashing, but toggling an output in the Signal I/O function
menu does not toggle the output’s status LED, the there is a circuit problem, or possibly
a blown driver chip, on the relay board.
If D1 on the Relay board is flashing and the status indicator for the output in question
(heater, valve, etc.) toggles properly using the Signal I/O function, but the output device
does not turn on/off, then the associated device (valve or heater) or its control device
(valve driver, heater relay) is malfunctioning.
Several of the control devices are in sockets and can easily be replaced. The table below
lists the control device associated with a particular function:
07266B DCN6485