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Discussion Starter #1
My second pyro probe for the Attitude has gone bad, each only lasted about two months. EGT's read low 100's or 60's. They are sending me a new one. Edge never did say if they tested my first probe to see what was wrong with it. I checked continuity on the second bad one. It has continuity between the probe tip and end of the yellow wire, but no continuity between the probe tip and end of the red wire. Does this simply mean that the red wires are shorting out? It seems wierd that I'd have two go bad.



on edit: mods, you can move this to Accessories if needed.


JoshEdited by: GMCSLEHD
 

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Having continuity between the case and the wires depends on the design of the probe. The two wires are welded together at the end. This bead is placed in the case and sealed. If the bead is placed in contact with the case, (non-isolated) the direct connection allows for a faster response. If it is not allowed to make contact, (isolated) the probe is less likely to be interfered with by electrical noise and ground loop problems but will have a slower response. To check a type K thermocouple, (Chromel and Alumel wires) you need a voltmeter that reads millivolts. At 70 degrees F, you will get 0.84 mv between the two wires. At 212 degrees F, this will go up to 4.10 mv and at 1000 degrees, it climbs to 22.26 mv. This voltage can sometimes trick a ohm meter so try reversing the leads and see if you get the same reading both ways. If there is no continuity between the wires, then it is bad. The bead weld may have broken or the plug connection to the wires may be bad. Edited by: case680e
 

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Discussion Starter #3
case680e,


Thanks for the explanation
. I'll try checking it with the DMM at room temp and in some boiling water to see what kind of mv readings i get.


Josh
 

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Case680e.


I know a very minimal amount about thermocouples, but from reading your post above it looks like the Juice/Attitude comes with a Type K thermocouple. There must be a spec/standard on how these devices operate over temperature (as you quoted volts per degree performance). My question, if one were to experience continued poor reliability from an Edge supplied thermocouple (as GMCSLEHD has above), is it possible to substitute another manufactures thermocouple in place of the Edge device (same form factor) as long as it is a Type K device? If so, do you (or does anyone else) know an equivalent substitute from a gauge manufacture that will work with the Juice/Attitude?


Thanks,


Alan
 

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Along that line, is it possible to hook the attitude up to my Autometer thermocouple and have both a gauge and the attitude hooked up at the same time?
 

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I don't have an Attitude and am making an assumption that it has a type K thermocouple. There are other types of thermocouples that use a different combination of wires. I don't know for sure that it is a type K. The EGT gages that I have seen all use a type K so I am assuming that the Attitude is the same. Type K thermocouples usually have a yellow connecter and will have a red and a yellow colored wire. The red wire goes to the negative terminal and the yellow to the positive. The link below takes you to tables of output in MV foe given temperatures for various types of thermocouples. http://www.conaxbuffalo.com/tech/emf.html


Any thermocouple probe of the same type should work as long as there are no isolation problems. I think I heard that the Attitude uses a non-isolated (grounded) type. If so, then either isolated or non-isolated will work. Connections most be made using connectors made of similar materials. The Chromel wire goes on the cromel terminal and the Alumel wire goes on the alumel terminal. No other type of metal can be in the circuit or you will have two areas of dissimilar metals and both will generate signals. This includes wire nuts, crimp connectors and solder. Only use a thermocouple connector for that type of wire.


Can two gages be run off the same probe? Maybe-maybe not. Remember that we are talking about very small voltages. Having two gages may degrade the signal to a point that neither will give a true reading. It all depends on the amplifier that drives the gage. You could try each gage separately and then combine both gage leads in the same plug and see if you get the same answer. If there is enough signal to keep both gages happy, then it could work as long they both use the same thermocouple type and isolation.
 

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Case - Thanks for the reply. I will have to look at the Attitude connection scheme. I am questioning in my mind whether they are as strict about the similar metals, connectors etc as you mention. I have no doubt your correct, just whether Edge followed through with the implementation (I remember the Thermal ME types making measurements on some electronic equipment a number of years ago,,,, they brought their rolls of special interconnect wiring with them.) Learn something everyday here on the "Place".


Regards,


AlanEdited by: OC_DMAX
 

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