Teledyne Model 300EU Motherboard, Status LED’s, A to D Conversion, Sensor Inputs, Heating, M300EU

THEORY OF OPERATION	M300EU
	Addendum to M300E/EM Manual P/N 04288

10.3.2.3. Status LED’s

This information replaces that found in Sections 10.4.5.5 of the M300E/EM Operators Manual.

•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 10-14 of the M300E/EM Operators Manual).

•They are:

		Table 10-2:	Relay Board Status LED’s
LED	COLOR	FUNCTION	STATUS WHEN LIT		STATUS WHEN DARK
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 Oven Heaters

HEATING

NOT HEATING

D5	GREEN	Sample/Cal Gas	Valve Open to	Valve Open to
		Valve Option	CAL GAS FLOW	SAMPLE GAS FLOW
D6	GREEN	Zero/Span Gas	Valve Open to	Valve Open to
		Valve Option	SPAN GAS FLOW	ZERO GAS FLOW
D7	GREEN	Shutoff Valve	Valve Open to	Valve CLOSED to
		Option	CAL GAS FLOW	CAL GAS FLOW
D8	GREEN	IR SOURCE	Source ON	Source OFF

10.3.3. MOTHERBOARD

The information found in Section 10.4.6 of the M300E/EM Operators Manual (P/N 04288) is applicable to the M300EU with the following additions:

10.3.3.1. A to D Conversion

Because the M300EU has much higher resolution and sensitivity than the M300E/EM, the possibility that temperature-coefficient related drift could occur in the 10.3.3.1. A to D conversion circuitry if there were a significant difference in temperature between the converter and the surrounding airspace. To prevent this, a fan direct heated air directly onto the A to D converter area of the motherboard to ensure that it is as close as possible to the current temperature of the oven area.

10.3.3.2. Sensor Inputs

OVEN TEMPERATURE SENSOR

A thermistor is located in the center of the insulated oven area (see Figure 3-1). It measures the analyzer’s inside temperature. This information is stored by the CPU and can be viewed by the user for troubleshooting purposes via the front panel display by selecting the test function OVEN TEMP or reported via the instruments TEST CHANNEL analog output (A4) by setting the output function also named OVEN TEMP.

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