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THEORY OF OPERATION
Model 300E Carbon Monoxide Analyzer
Instruction Manual
174
P/N 04288 Rev: A
Status LED’s
Eight LED’s are located on the Analyzer’s Relay board to show the current status on
the various control functions performed by the Relay Board (see Figure 6-8). They
are:
Table 10–1: Relay Board Status LED’s
LED
Color
Function
Status When Lit
Status When Unlit
D1
RED
Watchdog Circuit Cycles On/Off Every 3 Seconds under direct control of the
analyzer’s CPU.
D2
YELLOW
Wheel Heater
HEATING
NOT HEATING
D3 YELLOW
Bench
Heater HEATING
NOT
HEATING
D4 YELLOW
Spare
N/A
N/A
D5 GREEN
Sample/Cal
Gas
Valve Option
Valve Open to CAL GAS
FLOW
Valve Open to SAMPLE GAS
FLOW
D6 GREEN
Zero/Span
Gas
Valve Option
Valve Open to SPAN GAS
FLOW
Valve Open to ZERO GAS
FLOW
D7 GREEN
Shutoff
Valve
Option
Valve Open to CAL GAS
FLOW
Valve
CLOSED
to CAL GAS
FLOW
D8
GREEN
IR SOURCE
Source ON
Source OFF
STATUS LED’s
DC VOLTAGE TEST
POINTS
RELAY PCA
PN 04135
Figure 10-13: Location of Relay Board Status LED’s