Nmea I/O Testing - Raytheon ST60 Service Manual

18 ST60 Instruments Service Manual 83142-1
No fail codes are generated since stage 2 is an audio/visual check. The following can,
however, be used as a guide to isolate a problem:
Failure Mode
No illumination
Keypad Illumination failure
(LCD illumination will also be degraded)
Keypad illumination OK
but degraded LCD illumination
No beep when key pressed
LCD segment(s) missing completely
Faint LCD segments
Press Key 1 and Key 2 together momentarily to progress to exit self-test (stages 3
and 4 are not supported on this instrument).

NMEA I/O Testing

Note that there is no self-test for NMEA input/output. As a guidline, if NMEA has
failed, do the following:
1. Ensure that NMEA output has been turned ON in user CAL.
2. Ensure that the instrument is receiving seatalk data for translation to NMEA (e.g.
Heading, Latitude, Longitude etc...)
3. Voltage at NMEA_OUT+ should be approx 11.2v with 12v battery supply.
Current supplied from this pin to BATT- should limit at approx.80mA. If there is
a problem with this supply, check TR18, TR19 and associated components.
4. Connect a dummy load (1K resistor) across NMEA_OUT+ and NMEA_OUT-
and check for pulses at NMEA_OUT- If no pulses are seen, check R18 and TR5.
5. Disconnect dummy load and connect NMEA outputs to corresponding NMEA
inputs. Check for pulses at the junction of R59 and R60 (TP192). If no pulses are
seen, check R55-58, L7 and IC8.
6. Check the final stage output at TR4b (TP116)
Part 1. ST60 Instruments – Chapter 3. Multi
Action
Check TR14, TR13, TR15 and associated components.
Check all LEDs.
Check TR14, TR13, R22 and R23.
Check LED1-6 for open circuit.
Check TR14, TR15, RN3, R24.
Check LED 7 and 8 for open circuit.
Replace keyswitch.
Check LCD solder pins for poor/dry joints.
Check IC3 for unsoldered pins.
Check LCD pins for shorts.
Check IC3 for shorts.