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Model 300E Carbon Monoxide Analyzer
Instruction Manual
TROUBLESHOOTING & REPAIR PROCEDURES
P/N 04288 REV: A
197
11.1.4.3. Relay Board Status LED’s
STATUS LED’s
DC VOLTAGE TEST
POINTS
RELAY PCA
PN 04135
Figure 11-5: Relay Board Status LEDs
There are eight LED’s located on the Relay Board. The most important of which is
D1, which indicates the health of the I
2
C bus.
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 Mother Board, Keyboard or Relay
Board
§
Faulty Connectors/Wiring between Mother
Board, Keyboard or Relay Board
§
Failed/5 VDC Power Supply (PS1)
If D1 is blinking the other faults following LED’s can be used in conjunction with
DIAG
Menu Signal I/O to identify hardware failures of the relays and switches on
the Relay (see Section 7.4.1 and Appendix D).