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Any junctions with temperature changes across them? Is themocouple wire (and the right type) being used from end to end? Any other readings off?
Westach Tach/Oil/Fuel Tranducers
- Thread starter EchoCharlie1
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EchoCharlie1
New Member
No, yes and no.
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For some reason your CHT probes are not acting like thermocouples.
The 98 degrees is likely the temperature of the EMS module. Thermocouples read temp differences, so we add the thermocouple temp to the EMS temp. If your thermocouple always puts out 0.00V, then we just end up showing the EMS module temp.
Anyway, reasons that could be true:
1) They aren't thermocouples, they are resistors. Resistors hooked to thermocouple inputs always read zero.
2) They are shorted somewhere. Somewhere that isn't very warm.
The best way to check this on SkyView is on the EMS debug page. Scroll to one of the CHT inputs, with the engine at least somewhat warm. Does the voltage there read anything, or is it just zero? This voltage is before we do anything in software in SkyView so it's a great low level place to start.
The 98 degrees is likely the temperature of the EMS module. Thermocouples read temp differences, so we add the thermocouple temp to the EMS temp. If your thermocouple always puts out 0.00V, then we just end up showing the EMS module temp.
Anyway, reasons that could be true:
1) They aren't thermocouples, they are resistors. Resistors hooked to thermocouple inputs always read zero.
2) They are shorted somewhere. Somewhere that isn't very warm.
The best way to check this on SkyView is on the EMS debug page. Scroll to one of the CHT inputs, with the engine at least somewhat warm. Does the voltage there read anything, or is it just zero? This voltage is before we do anything in software in SkyView so it's a great low level place to start.
EchoCharlie1
New Member
First thing this evening, I'll check on that. They worked perfectly fine, the way they were wired, for the previous system (BMA One).
I'm down to that last little issue, besides one with my new Zaon XRX, that I'll address after researching that thread.
I'm down to that last little issue, besides one with my new Zaon XRX, that I'll address after researching that thread.
EchoCharlie1
New Member
Re: Westach Tach/Oil/Fuel Tranducers - UPDATE
Okay, I ordered the Dynon 25-pin wire harness and hooked directly to the CHT thermocouple wires coming through the firewall. After a 20-minute runup, the CHTs were STILL reading only about 84 degrees F.
Which wire of the harness (Red/Yellow/White) is considered positive and which is negative?
Thanks!
Okay, I ordered the Dynon 25-pin wire harness and hooked directly to the CHT thermocouple wires coming through the firewall. After a 20-minute runup, the CHTs were STILL reading only about 84 degrees F.
Which wire of the harness (Red/Yellow/White) is considered positive and which is negative?
Thanks!
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Red is negative for both,
Also:
red/white is CHT
red/yellow is EGT
But, what you're experiencing sounds like you don't have thermocouples at the other end of your harness. Where are your CHTs from? Are they the ones we sell?
Also:
red/white is CHT
red/yellow is EGT
But, what you're experiencing sounds like you don't have thermocouples at the other end of your harness. Where are your CHTs from? Are they the ones we sell?
jakej
Well-Known Member
....ahem DS - looks like I'll have to redo all my past installs with this 'new' clour coding ;D of course you did mean red/yellow = EGT & red/white = CHT ........just checking ;D
jakej
Well-Known Member
Any chance you've mistakenly connected the red/yellow wires to the CHT's 
just asking, sometimes.....anything can happen. It may explain what you are seeing.
Jake J
just asking, sometimes.....anything can happen. It may explain what you are seeing.Jake J
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Good catch Jake. Post above amended to be correct (so that you now appear to be a bit mad in your query)
EchoCharlie1
New Member
Wire harness from Dynon is labeled and installed correctly.
EGTs are hooked up to EGT leads from Dynon harness.
CHTs are hooked up to CHT leads from Dynon harness.
CHTs/EGTs are thermocoupler J-Type/K-type, respectively. Not purchased from Dynon, but were perfectly fine with BMA and was told that they would work with Dynon SV since they are in fact, J-type CHT thermocouplers. CHT leads are braid-shielded, EGT leads are not.
Enough guessing. : I am getting ~1150-1325 deg F on the EGTs, no more than ~110 deg F on the CHTs. I've installed/re-installed connections, bought the harness, reversed polarity and just about everything...I'm spending too much time with my head under the panel and my legs poking out the canopy and not enough time flying.
EGTs are hooked up to EGT leads from Dynon harness.
CHTs are hooked up to CHT leads from Dynon harness.
CHTs/EGTs are thermocoupler J-Type/K-type, respectively. Not purchased from Dynon, but were perfectly fine with BMA and was told that they would work with Dynon SV since they are in fact, J-type CHT thermocouplers. CHT leads are braid-shielded, EGT leads are not.
Enough guessing. :
I am getting ~1150-1325 deg F on the EGTs, no more than ~110 deg F on the CHTs. I've installed/re-installed connections, bought the harness, reversed polarity and just about everything...I'm spending too much time with my head under the panel and my legs poking out the canopy and not enough time flying.- Joined
- Mar 23, 2005
- Messages
- 13,226
BMA used Aerosance CHT probes for a while. These are not thermocouples, they are thermistors (temperature sensitive resistors). Are you 100% sure that you have thermocouple CHT's? A thermistor would act exactly like you describe.
You can check the probe with an ohmmeter. If it's a thermocouple, it will look like a dead short, with just a few ohms of resistance. If it's a thermistor, it will have much, much more resistance. I don't know exactly what to expect at room temp as I couldn't find a table for these probes in the few minutes I looked on-line.
If you want to prove that the thermocouple input is working, you can hook a 1.5V battery to one of the CHT input channels (AAA, AA, etc). This will cause it to rail out, reading 1800 degrees or -99 degrees depending which way you hook it up. At least you'd know the input is reading something.
You can check the probe with an ohmmeter. If it's a thermocouple, it will look like a dead short, with just a few ohms of resistance. If it's a thermistor, it will have much, much more resistance. I don't know exactly what to expect at room temp as I couldn't find a table for these probes in the few minutes I looked on-line.
If you want to prove that the thermocouple input is working, you can hook a 1.5V battery to one of the CHT input channels (AAA, AA, etc). This will cause it to rail out, reading 1800 degrees or -99 degrees depending which way you hook it up. At least you'd know the input is reading something.
EchoCharlie1
New Member
You see...THAT is why you guys get paid the big bucks! AND, that is why I have no problem paying for a good product...GOOD product support!
I'll double/triple/quadriple check the probes. All I know is that I am almost certain that they are J-type thermocouplers, BUT...I'll check and get back to you after running that recommended check with the battery.
Cheers!
I'll double/triple/quadriple check the probes. All I know is that I am almost certain that they are J-type thermocouplers, BUT...I'll check and get back to you after running that recommended check with the battery.
Cheers!