TELEDYNE API T300M - The Diagnostic Signal I;O Function; Status Leds; Motherboard Status Indicator (Watchdog)

083730300A DCN8101 Maintenance and Service 117
TEST
FUNCTIONS
(AS DISPLAYED)
INDICATED FAILURE(S)
SLOPE
Values outside range indicate
Contamination of the zero air or span gas supply
Instrument is miscalibrated
Blocked gas flow
Contaminated or leaking GFC Wheel (either chamber)
Faulty IR photo-detector
Faulty sample faulty IR photo-detector pressure sensor (P1) or circuitry
Invalid M/R ratio (see above)
Bad/incorrect span gas concentration due.
OFFSET
Values outside range indicate
Contamination of the zero air supply
Contaminated or leaking GFC Wheel (either chamber)
Faulty IR photo-detector
5.7.4 THE DIAGNOSTIC SIGNAL I/O FUNCTION
The signal I/O diagnostic mode allows access to the digital and analog I/O in the
analyzer. Some of the digital signals can be controlled through the touchscreen. These
signals, combined with a thorough understanding of the instrument’s Theory of Operation
(found in Section 6), are useful for troubleshooting in three ways:
• The technician can view the raw, unprocessed signal level of the analyzer’s critical inputs
and outputs.
• Many of the components and functions that are normally under algorithmic control of the
CPU can be manually exercised.
• The technician can directly control the signal level Analog and Digital Output signals.
This allows the technician to observe systematically the effect of directly controlling
these signals on the operation of the analyzer. The following flowchart shows an
example of how to use the Signal I/O menu to view the raw voltage of an input signal or
to control the state of an output voltage or control signal. (See also Section 5.7.15.1).
5.7.5 STATUS LEDS
Several color-coded light-emitting diodes (LEDs) are located inside the instrument to
assist in determining if the analyzer’s CPU, I
2
C bus and relay board, GFC Wheel and the
sync/demodulator board are functioning properly.
5.7.6 MOTHERBOARD STATUS INDICATOR (WATCHDOG)
DS5, a red LED, that is located on upper portion of the motherboard, just to the right of
the CPU board, flashes when the CPU is running the main program loop. After power-
up, approximately 30 to 60 seconds, DS5 should flash on and off. If characters are
written to the front panel display but DS5 does not flash then the program files have
become corrupted. If after 30 – 60 seconds neither the DS5 is flashing or no characters
have been written to the front panel display then the CPU is bad and must be replaced.