On 11 Jan 2004 12:03:07 -0800, the renowned jim rozen
wrote:

In article , Blake Loyd says...

... remove the flame sensor, disconnect it from
the controller at the controller, attach meter to lead end disconnected from
controller and base of sensor(ground), heat sensor with a propane torch to
see if it produces the 0.8uA minimum through the lead.
If it doesn't, disconnect the lead from the sensor and test the sensor
again to see if it produces the 0.8uA minimum. If it does the lead is bad.
If it doesn't the sensor is bad.

In this case, is the flame sensor a thermocouple?

These units use a rod sitting out in the open flame. They sense the
rectifying action of a flame, which is very insensitive to soot
contamination or other undesired side effects. Needless to say, a
false positive flame detection would be a very serious matter. Flame
out, gas valve stays open, ssssssssssssssssssssssssssss, mixing with
air, seeping out, searching, until it finds *another* flame, anywhere.

Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com