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Model T101 Instruction Manual Troubleshooting & Service
219
9.1.4.1. Motherboard Status Indicator (Watchdog)
DS5, a red LED on the upper portion of the motherboard, just to the right of the CPU
board, flashes when the CPU is running the main program. After power-up, DS5 should
flash on and off about once per second. If characters are written to the front panel
display but DS5 does not flash then the program files have become corrupted. Contact
Technical Support because it may be possible to recover operation of the analyzer. If, 30
- 60 seconds after a restart, DS5 is not flashing and no characters have been written to
the front panel display, the firmware may be corrupted or the CPU may be defective. If
DS5 is permanently off or permanently on, the CPU board is likely locked up and the
analyzer should not respond (either with locked-up or dark front panel).
Motherboard
CPU Status LED
Figure 9-3. CPU Status Indicator
9.1.4.2. CPU Status Indicator
The CPU board has two red LEDs. LED1 is the upper-most LED and is a +5V power
indicator, so it should always be on. However, both CPU LEDs only indicate if the CPU
is powered up properly and generally working. The lower LED will sometimes be
stable, and sometimes will blink. It can continue to blink even if the CPU or firmware
are locked up, and is not an effective indicator for debugging system problems.
9.1.4.3. Relay Board Status LEDs
The most important status LED on the relay board is the red I
2
C Bus watch-dog LED,
labeled D1 (or W/D), which indicates the health of the I
2
C communications bus. This
LED is located in the upper left-hand corner of the relay board when looking at the
electronic components. If D1 is blinking, then the other LED’s can be used in
conjunction with the DIAG menu I/O functions to test hardware functionality by
switching devices on and off and watching the corresponding LED go on or off. The
LED only indicates that the logic signal for an output has been activated. If the output
driver (i.e. the relay or valve driver IC) is defective, then the LED will light up, but the
attached peripheral device will not turn on.
07266B DCN6485