TELEDYNE API T703U - Heater Control; Relay PCA Status Leds and Watch Dog Circuitry; Figure 9-6: Heater Control Loop Block Diagram; Figure 9-7: Status LED Locations - Relay PCA

Teledyne API T703/T703U Calibrator Operation Manual Principles of Operation
187
Heater Control 9.2.3.2.
The relay PCA controls the DC heaters for the O
3
generator and photometer lamp
housing.
Thermistor(s)
(e.g. photometer sample gas temp.;
photometer UV lamp temp.; O
3
generator
lamp temp.; ect.)
RELAY PCA
DC
Control
Logic
MOTHER BOARD
A/D
Converter
(V/F)
CPU
O
3
Generator
Lamp Heater
PHOTOMETER
Lamp Heater
Figure 9-6: Heater Control Loop Block Diagram.
Relay PCA Status LEDs and Watch Dog Circuitry 9.2.3.3.
Sixteen LEDs are located on the calibrator‟s relay board (Figure 9-7) to indicate
the status of the calibrator‟s heating zones and some of its valves; included is a
general operating watchdog indicator. Table 9-1 shows the states of these LEDs
and their respective functionality. Not all LEDs are used.
D15 (Green) - Photometer Lamp Heater
D16 (Green) – O
3
Generator Lamp Heater
D7 (Green) – Photometer Meas/Ref Valve
D9 (Green) – O
3
Pump
D1 (RED)
Watchdog
Indicator
T703U only:
D10 (Green)
O
3
Divert Valve
T703U only: D11 (Green) – O
3
Generator Valve
D2 (Yellow) – Zero Air Pump Option
D8 (Green) – Zero Air Shutoff Valve Option
Figure 9-7: Status LED Locations – Relay PCA
07223D DCN7107