Teledyne 4060 manual Ignition and/or Flame Guard Circuit Checks

Series 4060 Maintenance

measure resistance between that wire and the remaining undisturbed terminal. Resistance of the thermistor varies with its surrounding temperature. A reading of between 10KOhms and 16Kohms at around 25°C may be measured. (Under very cold conditions, the resistance could be as high as 50KOhms; under hot conditions, just a few thousand ohms.) If the thermistor measures anywhere in this range, it is most likely OK. Otherwise, if the circuit is short or open, check the wires leading to the thermistor,

2.Check the heating element by measuring its resistance. Disconnect one of the heater wires from either terminal 2 or terminal 4 on the temperature control board P/N B30927, heater wires are black, and check the resistance between that wire and the remaining undisturbed terminal. If a reading of approximately 100 Ohms, then the heating element is most likely OK. If an open circuit is found, check the heater wires and a possible connector between the heater and temperature control board. If no problems are found, and the heater circuit is open, then replace the heater element.

Note: If any of the components located inside the isothermal chamber has failed, the instrument must be removed for service. If no problems are found with either the thermistor or the heater circuits, then replace the temperature control board.

5.3 Ignition and/or Flame Guard Circuit Checks

If the flame guard circuit will not hold the flame-out lamp off when the ignition procedure is employed (see section 4.4 Flame Ignition), perform the following procedure to isolate the problem (consult the system schematic for details of the circuit):

1.Disconnect the anode-igniter/flame guard thermistor cable from the socket.

2.Check the flame guard sensing thermistor by measuring the resistance between pins J4-3&4 of PCB part number B74671, disconnect the cable plug. The reading should be about 100 KΩ at room temperature. The actual resistance is not important, since the thermistor experiences radical changes in resistance as the temperature changes. No indication in a sufficiently high range on

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