rotorman Posted September 27, 2022 Report Posted September 27, 2022 The CHT #4 cylinder was indicating way higher than the other 3. I was reasonably sure the engine was fine. So I got a new CHT probe. During the installation I found that one of the two wires coming from the display was bare, without insulation, right at the connector as though it may have pulled partially out of the connector. I installed the new probe without further trouble shooting and found the new probe displayed no EGT. I'm reasonably sure that the bare wire had lost it's connection completely. The connection for the Insight Gem probe to display is two wires screwed together, one of the two being threaded. Where would I get a connector of this type? Or, could I cut both wires and use another type of connector. I know the probe works on resistance so is it possible to modify this connection without changing the resistance in the system? As you can tell from the question electricity was not my major in college. Quote
carusoam Posted September 27, 2022 Report Posted September 27, 2022 1 hour ago, rotorman said: The CHT #4 cylinder was indicating way higher than the other 3. I was reasonably sure the engine was fine. So I got a new CHT probe. During the installation I found that one of the two wires coming from the display was bare, without insulation, right at the connector as though it may have pulled partially out of the connector. I installed the new probe without further trouble shooting and found the new probe displayed no EGT. I'm reasonably sure that the bare wire had lost it's connection completely. The connection for the Insight Gem probe to display is two wires screwed together, one of the two being threaded. Where would I get a connector of this type? Or, could I cut both wires and use another type of connector. I know the probe works on resistance so is it possible to modify this connection without changing the resistance in the system? As you can tell from the question electricity was not my major in college. How about pics? Chts are mostly measured with thermocouples lately… But a few, are using a thermistor… What you are describing is a thermistor… where the wires are expected to be zero resistance compared to the thermistor… If it was a thermocouple… added tiny amounts of resistance would cause a problem, and variable metal types generate micro volt errors… The most reliable method… would be to visit the insight web site… and see what they have for sale to support their instruments… Best regards, -a- Quote
rotorman Posted September 27, 2022 Author Report Posted September 27, 2022 Here is a pic of the probe and connector. The wire that needs a new connector is the one that goes to the cockpit unit. 1 Quote
carusoam Posted September 27, 2022 Report Posted September 27, 2022 Time to check the details… That appears to be a thermocouple… where wire type and connector materials will be important… a note at a spruce said it was a J-Type TC… TC types are very dependent on using specific type wires… all are color coded to help… JPI typically uses K-type… Best regards, -a- Quote
rotorman Posted September 27, 2022 Author Report Posted September 27, 2022 So, are you saying that a wire coming from the control (display) unit that connects to the probe in the picture could not be cut and new OEM connector attached? Quote
philiplane Posted September 27, 2022 Report Posted September 27, 2022 20 hours ago, rotorman said: The CHT #4 cylinder was indicating way higher than the other 3. I was reasonably sure the engine was fine. So I got a new CHT probe. During the installation I found that one of the two wires coming from the display was bare, without insulation, right at the connector as though it may have pulled partially out of the connector. I installed the new probe without further trouble shooting and found the new probe displayed no EGT. I'm reasonably sure that the bare wire had lost it's connection completely. The connection for the Insight Gem probe to display is two wires screwed together, one of the two being threaded. Where would I get a connector of this type? Or, could I cut both wires and use another type of connector. I know the probe works on resistance so is it possible to modify this connection without changing the resistance in the system? As you can tell from the question electricity was not my major in college. You can cut the wires as needed and use ring terminals, or butt splices. The only requirement is to ensure the new connections are clean, and tight. It is good practice to double over the extension wires due to their small gauge (usually 24 gauge) which will fill the connector better and reduce the chance of breakage. The main concern is that you connect the wires correctly, since the polarity matters. 1 Quote
rotorman Posted September 27, 2022 Author Report Posted September 27, 2022 2 hours ago, philiplane said: You can cut the wires as needed and use ring terminals, or butt splices. The only requirement is to ensure the new connections are clean, and tight. It is good practice to double over the extension wires due to their small gauge (usually 24 gauge) which will fill the connector better and reduce the chance of breakage. The main concern is that you connect the wires correctly, since the polarity matters. I called Insight in Canada and they said exactly the same. Go to an automotive shop and get a ring connector. The system does not care about the length of the wire or the type of the connector. Thanks for the additional information on wiring. Quote
PT20J Posted September 27, 2022 Report Posted September 27, 2022 9 minutes ago, rotorman said: I called Insight in Canada and they said exactly the same. Go to an automotive shop and get a ring connector. The system does not care about the length of the wire or the type of the connector. Thanks for the additional information on wiring. Ugh. That will work, but better to use aircraft quality PIDG ring terminals which have better strain relief. And use a proper crimp tool. https://www.te.com/usa-en/products/brands/pidg.html?tab=pgp-story https://www.aircraftspruce.com/catalog/elpages/insulterms.php?clickkey=9446 1 Quote
rotorman Posted September 27, 2022 Author Report Posted September 27, 2022 Got it. Thx. I have a crimping tool and will get the superior ring connector. 1 Quote
MikeOH Posted September 28, 2022 Report Posted September 28, 2022 Yellow and red is a Type K; make sure that is what is specified for your instrument. Also, do NOT use copper wire to 'extend' the leads. All wire back to the instrument MUST be the proper (matching) thermocouple extension wire. Shouldn't be a problem if you are just connecting the new TC to the existing wiring (as long as it was correct to begin with!) 2 Quote
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