Finding the right cylinder probe...

fiveoboy01

fiveoboy01

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Dirty B
My airplane has a GEM 610 engine monitor and a tanis preheater.

The probes are dual probe - to heat the cylinder and also for monitoring the CHT.

Today I plugged the tanis in to check its operation and one cylinder is not getting any heat. I think I need to get a new probe, although I do need to check and make sure I have power to it. I am not sure of the voltage at the spade connectors for the heating part of the probe, so I wasn't about to stick a paperclip in there to check for power and I didn't have any other test equipment but I'll make sure to check for that.

Assuming the probe is bad... I'm not sure which one I need as Tanis lists several different types on their website(K type, J type, grounded and ungrounded, etc...).

Is there any easy way to tell which one I need to buy?

About all the info I have on the probes that are in there are they are the screw in type, two blue wires coming out with spades on the end for the heat part, and a single braided jacket that has a red/white wire in it for the CHT.
 
Thanks. That narrows it down.

Looks like there are 4 type J to choose from. male or female connector, and for a grounded or ungrounded engine monitor. Any easy way to figure the grounded/ungrounded thing out? The connector is no issue, as they're deutsch and I will replace the spades on one the other end with whatever matches.
 
fiveoboy01 said:
Thanks. That narrows it down.

Looks like there are 4 type J to choose from. male or female connector, and for a grounded or ungrounded engine monitor. Any easy way to figure the grounded/ungrounded thing out? The connector is no issue, as they're deutsch and I will replace the spades on one the other end with whatever matches.
Click to expand...

Again, I have no knowledge of your specific probes, but in general thermocouple terminology a grounded thermocouple probe has its thermocouple welded to the interior of the metal sheath that encloses the thermocouple, and an ungrounded probe is insulated from the metal sheath by a thermal and electrical insulator (all that I know of use ceramic powder). So you should be able to determine which you have by measuring the electrical continuity between either of the thermocouple wires and the metal sheath. If there is electrical continuity between them, then the probe should be a grounded probe. If there is no continuity between a thermocouple wire and the sheath, then the probe is ungrounded.

This test can give incorrect results in the event that the sheath of an ungrounded probe is bent enough that the thermocouple leads touch the inside of the sheath. They will show electrical continuity due to contact of the thermocouple wire with the sheath at the point of the bend.
 
Thanks for the help. I am skilled in the use of a multi-meter and will do some checking tomorrow. Additionally, a Tanis rep left me a message with a few things to check.

Question in the case of an ungrounded probe "shorting" because the thermocouple wires are touching the metal sheath.. Both wires are insulated where they exit the metal sheath - in the case of making contact internally due to a bend, would the insulation on the wire also need to be broken? I assume the wires are insulated all the way up to the sensor body but I'm not certain.
 
Guys, I feel like a dope.

One of the probes had been replaced and had the part number tag crimped on it.

Sorry for wasting everyone's time:redface:
 
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