Valve Control; Heater Control; Relay Pca Status Leds & Watch Dog Circuitry; Figure 10-6: Heater Control Loop Block Diagram - Teledyne T700 Operation Manual

Principles of Operation

10.3.3.1. Valve Control

10.3.3.2. Heater Control

10.3.3.3. Relay PCA Status LEDs & Watch Dog Circuitry
274
NEVER REMOVE THIS SAFETY SHIELD WHILE THE INSTRUMENT IS PLUGGED
IN AND TURNED ON. THE CONTACTS OF THE AC RELAY SOCKETS BENEATH
THE SHIELD CARRY HIGH AC VOLTAGES EVEN WHEN NO RELAYS ARE
The relay PCA also hosts two valve driver chips, each of which can drive up four valves.
In the T700, the relay PCA controls only those valves associated with the O
and photometer options. All valves related to source gas and diluent gas flow are
controlled by a separate valve driver PCA (see Section 10.3.4).
The relay PCA controls the various DC heaters related to the O
photometer options.
Thermistor(s)
(
e.g. photometer sample gas temp.;
photometer UV lamp temp.; O generator
3
lamp temp.; ect.)

Figure 10-6: Heater Control Loop Block Diagram.

Thirteen LEDs are located on the calibrator‟s relay PCA to indicate the status of the
calibrator‟s heating zones and some of its valves as well as a general operating watchdog
indicator. Table 10-1 shows the status of these LEDs and their respective functionality.
Teledyne API – Model T700 Dynamic Dilution Calibrator
WARNING
PRESENT
MOTHERBOARD
RELAY PCA
DC
Control
Logic
O Generator
PHOTOMETER
3
Lamp Heater
Lamp Heater
3
A/D
Converter
(V/F)
CPU
06873E DCN7106
generator
3
generator and