anthonydesmet Posted December 30, 2020 Report Share Posted December 30, 2020 Hello Everyone, Went for a short flight yesterday to keep adding up break in hours on new engine and I had a new issue.... info: loud squeal in headset when cockpit com switch put in crew/cabin. You could still here it a little in the background when the switch is in pilot isolate but not as based. Severe safety of flight issue when in crew com position. - noise was negligible on ground but still there. Noise grew in amplitude and volume with increase in prop RPM. Above 1800 RPM is when noise was the worst. Noise also changed amplitude and volume with increase and decrease of prop RPM - When I turned the alternator field switch off (right half of alternator switch) the sound went away. 14V Single alternator system. TSIO-360-MB - with both alternator switches on I showed about 13.1 volts on JPI-730. With field switch off the volts read 13.5 so a slight increase in charge. Background: - aircraft just had an engine overhaul and I flew 10 hours in last two weeks with no issue. Alternator was overhauled also during engine overhaul - after my first post overhaul flight two weeks ago I mentioned to my mechanic that the engine had a rough time turning over due to battery and that I only saw the 13 volts on the JPI but looked like system was charging. - during that post flight check mechanic said I needed a new voltage regulator. New regulator went in last week with 10 hour oil change. Yesterday was first flight with new regulator. mechanic thinks it still might be overhauled alternator. I think I have summarized everything..... thoughts? Quote Link to comment Share on other sites More sharing options...
PT20J Posted December 30, 2020 Report Share Posted December 30, 2020 Might be a bad alternator diode. 1 Quote Link to comment Share on other sites More sharing options...
milotron Posted December 30, 2020 Report Share Posted December 30, 2020 Hi, What is on the other side of the split alternator switch? I have a similar 262 but with dual alternators and that switch has the two fields on it. I would think the alt noise would show up in all comm modes, but you should be seeing 13.7-13.9 if the alternator is charging, and certainly not less with the field off. I had issue with my gear drive alternator causing similar issue that turned out being a nut had fallen into the alt, rattled around and thrashed the windings. Was this the first flight with the new regulator? The noise has only occurred with the new regulator? If the alternator is truly gone, the regulator might be working overtime trying to boost the field into producing anything. Agreed it may be a bad diode or two causing the AC ripple in the system. 1 Quote Link to comment Share on other sites More sharing options...
toto Posted December 30, 2020 Report Share Posted December 30, 2020 What kind of headset is it? As crazy as it sounds, I had a horrible screeching sound in my Bose A20 and I went down every rabbit hole trying to isolate the source of the noise. Turned out that you can’t use lithium batteries in an A20. I replaced with alkaline, and never had the problem again. 1 Quote Link to comment Share on other sites More sharing options...
dzeleski Posted December 30, 2020 Report Share Posted December 30, 2020 12 minutes ago, toto said: What kind of headset is it? As crazy as it sounds, I had a horrible screeching sound in my Bose A20 and I went down every rabbit hole trying to isolate the source of the noise. Turned out that you can’t use lithium batteries in an A20. I replaced with alkaline, and never had the problem again. If you have a sensitive device just charge the batteries more often. The issue is that cheaper rechargeable batteries drop off in voltage differently then a single use battery does. I'd pretty much only recommend using Eneloop Pro batteries and have never had a single issue with them even when the device says not to use rechargeable batteries. Quote Link to comment Share on other sites More sharing options...
anthonydesmet Posted December 30, 2020 Author Report Share Posted December 30, 2020 Definitely not headsets Quote Link to comment Share on other sites More sharing options...
toto Posted December 30, 2020 Report Share Posted December 30, 2020 44 minutes ago, dzeleski said: If you have a sensitive device just charge the batteries more often. The issue is that cheaper rechargeable batteries drop off in voltage differently then a single use battery does. I'd pretty much only recommend using Eneloop Pro batteries and have never had a single issue with them even when the device says not to use rechargeable batteries. I’m only dealing with single-use batteries.. I’ve never tried rechargeables in a headset. Bose says that only alkaline batteries may be used (but I didn’t know this when I spent months chasing down the source of the ear-splitting noise). The screeching from lithium batteries was really awful. Quote Link to comment Share on other sites More sharing options...
toto Posted December 30, 2020 Report Share Posted December 30, 2020 Just now, toto said: I’m only dealing with single-use batteries.. I’ve never tried rechargeables in a headset. Bose says that only alkaline batteries may be used (but I didn’t know this when I spent months chasing down the source of the ear-splitting noise). The screeching from lithium batteries was really awful. Fwiw... here’s the quote from the Bose manual: ”Warning: Replace batteries with alkaline batteries only. Do not use any other battery chemistries.” Quote Link to comment Share on other sites More sharing options...
PT20J Posted December 31, 2020 Report Share Posted December 31, 2020 4 hours ago, toto said: Fwiw... here’s the quote from the Bose manual: ”Warning: Replace batteries with alkaline batteries only. Do not use any other battery chemistries.” Yeah, Lightspeed says that also. But I’ve successfully used rechargeable (NiMH) batteries in each headset. Also successfully used Energizer Lithium AA non-rechargables. I used the rechargeables when I was flying part 135, 6 hrs/day and the alkalines started getting expensive. Since NiMH batteries don’t have memory, you can recharge them often and then you never have to worry about changing them in flight. Skip Quote Link to comment Share on other sites More sharing options...
toto Posted December 31, 2020 Report Share Posted December 31, 2020 15 minutes ago, PT20J said: Yeah, Lightspeed says that also. But I’ve successfully used rechargeable (NiMH) batteries in each headset. Also successfully used Energizer Lithium AA non-rechargables. I used the rechargeables when I was flying part 135, 6 hrs/day and the alkalines started getting expensive. Since NiMH batteries don’t have memory, you can recharge them often and then you never have to worry about changing them in flight. Skip Yeah, dunno. I never had the problem with headsets from other manufacturers, and never had a problem with Bose before the A20. But I would have sworn up and down that the A20 issue was something coming from the aircraft and not from the headset - until I finally exhausted other options and tried the alkaline thing. Quote Link to comment Share on other sites More sharing options...
GeeBee Posted December 31, 2020 Report Share Posted December 31, 2020 It sounds weird, but when I had the same problem in the SuperCub, I cleaned up the battery ground on the advice of others on the SuperCub.org forum and it worked. Headset went crystal clear. I've experience it on other aircraft as well and cleaning up the battery ground, both the terminal on the battery and the cable to the airframe has worked. Do not forget the engine to airframe ground as well. 2 Quote Link to comment Share on other sites More sharing options...
PT20J Posted December 31, 2020 Report Share Posted December 31, 2020 16 minutes ago, GeeBee said: It sounds weird, but when I had the same problem in the SuperCub, I cleaned up the battery ground on the advice of others on the SuperCub.org forum and it worked. Headset went crystal clear. I've experience it on other aircraft as well and cleaning up the battery ground, both the terminal on the battery and the cable to the airframe has worked. Do not forget the engine to airframe ground as well. Always a good idea to try the simple stuff first 1 Quote Link to comment Share on other sites More sharing options...
amillet Posted December 31, 2020 Report Share Posted December 31, 2020 Our aircraft came with standard/panel powered plugs. I bought Lightspeeds headsets with the six pin round connectors. No more batteries. The batteries always seemed to die at high workload moments when I couldn’t change them Quote Link to comment Share on other sites More sharing options...
anthonydesmet Posted December 31, 2020 Author Report Share Posted December 31, 2020 11 hours ago, GeeBee said: It sounds weird, but when I had the same problem in the SuperCub, I cleaned up the battery ground on the advice of others on the SuperCub.org forum and it worked. Headset went crystal clear. I've experience it on other aircraft as well and cleaning up the battery ground, both the terminal on the battery and the cable to the airframe has worked. Do not forget the engine to airframe ground as well. I like this idea. Easy to check and will let you know Quote Link to comment Share on other sites More sharing options...
skykrawler Posted December 31, 2020 Report Share Posted December 31, 2020 Your description make it difficult to troubleshoot. What kind of audio panel? It sounds like your system is not charging correctly based on the JPI indicating 13.1volts. The system can't charge with the field switch off and you say the voltage went up with the field off. It might do that with engine not running. With the engine running the system should be making a more like 13.8 volts. What did your voltage run before the engine was overhauled? Diode is definite possibility. Your mechanic doesn't know how to troubleshoot alternator systems - make sure you keep the old regulator as it is likely still good. The alternator should still be under warranty. 1 Quote Link to comment Share on other sites More sharing options...
anthonydesmet Posted January 2, 2021 Author Report Share Posted January 2, 2021 On 12/30/2020 at 1:44 PM, milotron said: Hi, What is on the other side of the split alternator switch? I have a similar 262 but with dual alternators and that switch has the two fields on it. I would think the alt noise would show up in all comm modes, but you should be seeing 13.7-13.9 if the alternator is charging, and certainly not less with the field off. I had issue with my gear drive alternator causing similar issue that turned out being a nut had fallen into the alt, rattled around and thrashed the windings. Was this the first flight with the new regulator? The noise has only occurred with the new regulator? If the alternator is truly gone, the regulator might be working overtime trying to boost the field into producing anything. Agreed it may be a bad diode or two causing the AC ripple in the system. I think @milotronmight be the winner but will know more Monday. Cleaned and reset all ground connections for battery and engine but no change. Also swapped out intercom boxes with hanger neighbor and no change but as milotron stated I should have the noise in all comm switch settings but do not. We have isolated that to separate issue in how my comms are wired. However belt driven alternator produces nothing and with right half of switch on we suspect voltage regulator is working overtime. Turn belt drive alternator off and no noise issue. also engine driven alternator has been adjusted to push 13.8 volts now. more to follow this week Quote Link to comment Share on other sites More sharing options...
Vno Posted January 6, 2021 Report Share Posted January 6, 2021 Just had this same issue. Bad connector on the Alternator field wire to the Alternator. Replaced and it is much better. Brian Quote Link to comment Share on other sites More sharing options...
carusoam Posted January 6, 2021 Report Share Posted January 6, 2021 Ant, Read the advice from PMC above, twice.... He has a ton of experience in the headset, sound, and grounds arena... PP thoughts only, -a- Quote Link to comment Share on other sites More sharing options...
anthonydesmet Posted January 7, 2021 Author Report Share Posted January 7, 2021 @milotronand @PT20Jare both the winners. Lost a diode in the belt drive alternator and when turning field switch off resulted in voltage regulator over compensation. All good now! 3 Quote Link to comment Share on other sites More sharing options...
carusoam Posted January 7, 2021 Report Share Posted January 7, 2021 Great follow-up and score keeping! -a- Quote Link to comment Share on other sites More sharing options...
milotron Posted January 7, 2021 Report Share Posted January 7, 2021 Great to hear. The belt drive unit is easy to service. The other one requires tipping the engine forward. 1 Quote Link to comment Share on other sites More sharing options...
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