General Troubleshooting & Service Teledyne API T703/T703U Calibrator Operation Manual
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8.3. USING THE INTERNAL ELECTRONIC STATUS LEDS

Several LEDs are located inside the instrument to assist in determining if the calibrators
CPU, I2C bus and Relay PCA are functioning properly.

8.3.1. 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 – 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, contact Technical Support because it may be possible to recover
operation of the calibrator. If after 30 – 60 seconds neither DS5 is flashing and no
characters have been written to the front panel display then the CPU is bad and must be
replaced.
Motherboard
CPU Status LED
Figure 8-2: CPU Status Indicator

8.3.2. RELAY PCA STATUS LEDS

There are sixteen status LEDs on the Relay PCA. Not all are used on this model.

8.3.2.1. I2C Bus Watchdog Status LEDs

The most important is D1 (see Figure 8-3), which indicates the health of the I2C bus.
Table 8-4: Relay PCA Watchdog LED Failure Indications
LED Function Fault Status Indicated Failure(s)
D1
(Red)
I2C bus Health
(Watchdog Circuit)
Continuously ON
or
Continuously OFF
Failed/Halted CPU
Faulty Motherboard or Relay PCA
Faulty Connectors/Wiring between Motherboard 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.
07223C DCN6572