Tom Baker Posted February 20, 2014 Report Share Posted February 20, 2014 Hey guys looking for some thoughts on this. I'm working on a 2006 CTSW, that has some really loud alternator noise coming through the intercom. The noise increases with RPM of the engine. The owner says that it has been that way since he bought the airplane. If I turn the radio off the noise is still there. When I checked the capacitor one wire was broken off by the time I clipped the tywraps and got it out where I could see it. I installed a new capacitor, and the noise was still there. I tried a different rectifier/regulator, and still had noise. Any thoughts on where to look next? The owner seems OK with it, but I'm not. Link to comment Share on other sites More sharing options...
Roger Lee Posted February 20, 2014 Report Share Posted February 20, 2014 I would have sod the capacitor too, but now I would check the ground wire for the comms and the overall ground wires. Maybe install the extra ground wire like I did. I has cured several ills for many people. Link to comment Share on other sites More sharing options...
Tom Baker Posted February 20, 2014 Author Report Share Posted February 20, 2014 The airplane already has the extra ground from the engine to the battery, and the engine to the inside ground connection. Link to comment Share on other sites More sharing options...
Roger Lee Posted February 20, 2014 Report Share Posted February 20, 2014 Have you checked all the wire coonectors on the back of the intercom. Link to comment Share on other sites More sharing options...
Anticept Posted February 20, 2014 Report Share Posted February 20, 2014 Turn off the intercom and see if it is still there. The intercom i have picks up alternator noise easily, and that is probably where the problem is if it is not the capacitor. I soldered the terminal connectors on the capacitor on my CTLS, because the crimping don't seem to have a good enough connection. Link to comment Share on other sites More sharing options...
Tom Baker Posted February 20, 2014 Author Report Share Posted February 20, 2014 Have you checked all the wire coonectors on the back of the intercom. Not yet, but going to do that this afternoon. Link to comment Share on other sites More sharing options...
Tom Baker Posted February 20, 2014 Author Report Share Posted February 20, 2014 Turn off the intercom and see if it is still there. The intercom i have picks up alternator noise easily, and that is probably where the problem is if it is not the capacitor. I soldered the terminal connectors on the capacitor on my CTLS, because the crimping don't seem to have a good enough connection. On the SW all the audio comes through the intercom. With the intercom off you hear nothing in the headsets. Link to comment Share on other sites More sharing options...
Anticept Posted February 20, 2014 Report Share Posted February 20, 2014 On the SW all the audio comes through the intercom. With the intercom off you hear nothing in the headsets.Still doesn't exclude the intercom being the one picking up the noise . Radio systems are pretty spectacular at filtering noise, I've yet to see a radio be the problem when it isn't the wiring or the antennas. Try taking a sizable capacitor (at least as big as the alternator one) and bridging it across the power of the intercom. Dave does it on CTs that don't seem to settle down via normal methods. How you splice them in is up to you. Link to comment Share on other sites More sharing options...
Tom Baker Posted February 20, 2014 Author Report Share Posted February 20, 2014 Still doesn't exclude the intercom being the one picking up the noise . Radio systems are pretty spectacular at filtering noise, I've yet to see a radio be the problem when it isn't the wiring or the antennas. Try taking a sizable capacitor (at least as big as the alternator one) and bridging it across the power of the intercom. Dave does it on CTs that don't seem to settle down via normal methods. How you splice them in is up to you. You said try and turn off the intercom. The point is when the intercom is off there is no audio output to hear any noise. If you meant turn of the radio I have tried that with no change. Turning the altenator switch off makes the problem go away. I didn't find any loose wires in the plug for the intercom, and the path to ground was .3 ohms. Link to comment Share on other sites More sharing options...
Anticept Posted February 20, 2014 Report Share Posted February 20, 2014 You said try and turn off the intercom. The point is when the intercom is off there is no audio output to hear any noise. Gotcha. Put a capacitor in parallel with the intercom and see what happens. If it solves the problem, consider doing a permanent install. Link to comment Share on other sites More sharing options...
FastEddieB Posted February 20, 2014 Report Share Posted February 20, 2014 You said try and turn off the intercom. The point is when the intercom is off there is no audio output to hear any noise. If you meant turn of the radio I have tried that with no change. Does that mean a faulty intercom makes the plane NORDO? Link to comment Share on other sites More sharing options...
Tom Baker Posted February 20, 2014 Author Report Share Posted February 20, 2014 Does that mean a faulty intercom makes the plane NORDO? In the early airplanes the answer is yes, but they changed that somewhere along the line with the LS. Link to comment Share on other sites More sharing options...
Anticept Posted February 20, 2014 Report Share Posted February 20, 2014 In the early airplanes the answer is yes, but they changed that somewhere along the line with the LS. What intercom is installed? Link to comment Share on other sites More sharing options...
FastEddieB Posted February 20, 2014 Report Share Posted February 20, 2014 In the early airplanes the answer is yes, but they changed that somewhere along the line with the LS. Thanks. I asked because that would not be a great design. In a Cirrus if you go to the "Essential" Bus, the audio panel/intercom is not on it, so it powers off. You can still communicate with ATC, but not with each other. And in my Sky Arrow, I just found out a fried intercom, when switched off, still allowed me to hear ATC. Link to comment Share on other sites More sharing options...
Tom Baker Posted February 20, 2014 Author Report Share Posted February 20, 2014 What intercom is installed? PS Engineering 3000. The airplane has the standard Dynon D100/120, Garmin package. Link to comment Share on other sites More sharing options...
Anticept Posted February 20, 2014 Report Share Posted February 20, 2014 PS Engineering 3000. Do you know which part number? I ask because the pilot side is supposed to have a failsafe mode, and I am wondering if this is an old model that isn't in the manual anymore. Of course, they might not have wired it either . Are the leads to the headphone jacks independent shielded wires? Link to comment Share on other sites More sharing options...
Tom Baker Posted February 21, 2014 Author Report Share Posted February 21, 2014 Do you know which part number? I ask because the pilot side is supposed to have a failsafe mode, and I am wondering if this is an old model that isn't in the manual anymore. Of course, they might not have wired it either . Are the leads to the headphone jacks independent shielded wires? I would have to look on the wiring to tell. I will have to also check the PN. I just remember the change being mentioned one year while I was at Sebring. Link to comment Share on other sites More sharing options...
Anticept Posted February 21, 2014 Report Share Posted February 21, 2014 PS engineering says all the wires should be shielded, but sometimes I feel like that's a bit overkill. I am not entirely certain of the wiring configuration for the intercom. I know that the installation manual makes brief mentions of various pin features, one of which is the failsafe mode on unswitched input #1 (pin 17). EDIT: Pilot connection and aircraft radio are connected together if the unit loses power or is turned off. If this is not happening, either wiring is incorrect, or the intercom is defective. Check to see if the COPILOT has inadvertently been wired to the pilot side... Finally, make sure that the intercom has a nice direct path to battery ground. If it has multiple paths to ground, this can lead to interference. Multiple ground paths are normally not a problem in DC circuits, but rotax engines are noisy, so inductance can become great enough to affect the intercom. Again, have another look at that capacitor. N566FD was noisy since the day we first got her (she's had a lot of wiring problems that I have been sorting out), and now the intercom is QUIET because I soldered the capacitor connectors. Link to comment Share on other sites More sharing options...
Doug G. Posted February 21, 2014 Report Share Posted February 21, 2014 Isn't there an old SB on Garmin radios for noise? Link to comment Share on other sites More sharing options...
Tom Baker Posted February 21, 2014 Author Report Share Posted February 21, 2014 PS engineering says all the wires should be shielded, but sometimes I feel like that's a bit overkill. I am not entirely certain of the wiring configuration for the intercom. I know that the installation manual makes brief mentions of various pin features, one of which is the failsafe mode on unswitched input #1 (pin 17). EDIT: Pilot connection and aircraft radio are connected together if the unit loses power or is turned off. If this is not happening, either wiring is incorrect, or the intercom is defective. Check to see if the COPILOT has inadvertently been wired to the pilot side... Finally, make sure that the intercom has a nice direct path to battery ground. If it has multiple paths to ground, this can lead to interference. Multiple ground paths are normally not a problem in DC circuits, but rotax engines are noisy, so inductance can become great enough to affect the intercom. Again, have another look at that capacitor. N566FD was noisy since the day we first got her (she's had a lot of wiring problems that I have been sorting out), and now the intercom is QUIET because I soldered the capacitor connectors. You know maybe I should check the pilot side before I say it doesn't work, but I do remeber some change that had to be made in the 2009-2010 time frame. The leads on the capacitor that I removed were soldered, so they went back that way. Link to comment Share on other sites More sharing options...
Tom Baker Posted February 21, 2014 Author Report Share Posted February 21, 2014 Isn't there an old SB on Garmin radios for noise? Doug, the noise is still there with the radeo turned off. Link to comment Share on other sites More sharing options...
Tom Baker Posted February 21, 2014 Author Report Share Posted February 21, 2014 I did check and you can hear the radio on the pilot side with the intercom off. I'm just so used to being on the right side of the airplane. Link to comment Share on other sites More sharing options...
Anticept Posted February 21, 2014 Report Share Posted February 21, 2014 I did check and you can hear the radio on the pilot side with the intercom off. I'm just so used to being on the right side of the airplane. Alright, now, if you run the airplane and turn off the intercom, the noise should stop completely. If it does, the intercom is receiving too much noise from the power system, and a nice sized capacitor in parallel to it will solve that problem. Or, what you can do is run a wire from the intercom to as close to the battery negative terminal as possible. Link to comment Share on other sites More sharing options...
Tom Baker Posted February 22, 2014 Author Report Share Posted February 22, 2014 I had a chance to run it again. I found that if I turn off the GPS at the circuit breaker the noise goes away. I then pulled the audio plug on the GPS, and the noise went away. I'm going to get a 3.5mm groundloop isolator transformer to put in the audio line from the GPS. I hope that takes care of it. Link to comment Share on other sites More sharing options...
Anticept Posted February 22, 2014 Report Share Posted February 22, 2014 I had a chance to run it again. I found that if I turn off the GPS at the circuit breaker the noise goes away. I then pulled the audio plug on the GPS, and the noise went away. I'm going to get a 3.5mm groundloop isolator transformer to put in the audio line from the GPS. I hope that takes care of it. I'm having the same problem with noise from the GPS. I didn't have time to really look for the issue yet, but you gave me some ideas. Also, you know there are settings in the x96 series for the speaker type? It should be set to headphone. Link to comment Share on other sites More sharing options...
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