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Troubleshooting and Service Teledyne API T801 NDIR CO2 Analyzer Operation Manual
186
11.2. USING THE INTERNAL ELECTRONIC STATUS LEDS
Several LEDs are located inside the instrument to assist in determining if the
analyzer’s CPU, I
2
C bus and relay board are functioning properly.
11.2.1. CPU STATUS INDICATOR
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.
Motherboard
CPU Status LED
Figure 11-3: CPU Status Indicator
11.2.2. RELAY PCA STATUS INDICATORS
There are sixteen status indicator LEDs located on the Relay PCA. Some are not
used on this model.
11.2.2.1. I
2
C BUS WATCHDOG STATUS LEDS
The most important is D1 (which indicates the health of the I
2
C bus).
Table 11-3: Relay PCA Watchdog LED Failure Indications
LED Function Fault Status Indicated Failure(s)
D1
(Red)
I
2
C bus Health
(Watchdog Circuit)
Continuously ON
or
Continuously OFF
Failed/Halted CPU
Faulty Motherboard, Keyboard or Relay PCA
Faulty Connectors/Wiring between Motherboard,
Keyboard or Relay PCA
Failed/Faulty +5 VDC Power Supply (PS1)
If D1 is blinking, then the other LEDs can be used in conjunction with DIAG
Menu Signal I/O to identify hardware failures of the relays and switches on the
Relay PCA.
07274B DCN6418