Alternator Noise

[jetdriven]

On June 5, 2016 at 3:29 PM, jetdriven said:

the PP unit has a 6mm output post. I am guessing it is this one, and I think Im gonna order one to see. http://www.aspwholesale.com/rectifier-nd-p1359.html

 

To do a dynamic functional test of the rectifier assembly, put a digital volt-omh-meter on the outpost when the engine is running. Ground the other lead.  Set the DVOM to AC volts and and you are looking for no more than 1 volt AC, preferrably less than .5 or .2 but I have a feeling these units are fairly on the noisy side for aircraft so maybe < 1 VAC is all you'll get.  You can also check the individual diodes with the ohm meter.  continuity in one direction, open circuit in the other.

 

my problem is  constant whine which increases in volume with higher load on the alternator, the pitch seems constant. with enough load, such as all lights on, the stormscope WX-1000 inhibits. pulling the alternaotr field breaker kills the whine and immediately brings back the sotrmscope.  SO I think its AC in the skin, freaking the Stormscope out.  Reading these articles, makes me think its the regulator, however,  because the pitch doesnt change with RPM..  I have the original OECO or electrodelta mechanical voltage regulators.   http://www.eham.net/articles/15113      http://www.avweb.com/news/maint/182896-1.html

 

I did clean the battery terminals, no corrosion and no improvement.  I also have an Aera 500 wiht the flying lead cable plugged into the audio panel, perhaps its a ground loop whine but that doesnt explaint the SS acting up.

 

 

This rectifier fits in the AL12-P70 alternator. 40$ shipped is a whole lot better than 600$..

 

the INR720P.

http://www.aspwholesale.com/rectifier-nd-p1359.html

 

bad news, nothing changed, still the noise int he headset and the stormscope inhibit. 

Edited July 8, 2016 by jetdriven

[bhardeman]

Sorry to bring back an old thread.  Did you ever figure this out?  I'm having a similar issue with my stormscope after installing a brand new plane power alternator.

[carusoam]

Welcome aboard bhard...

Going on the posts near the end...

They are discussing replacing the rectifier...

The rectifier is made up of a bridge of diodes...

Diodes don’t last forever...

Finding failed diodes is pretty easy... replacing them probably requires a mechanic...

PP thoughts only, not a mechanic...

Best regards,

-a-

[bhardeman]

Thanks.  I followed the diode theory, but the end of jetdriven's last post said "bad news, nothing changed, still the noise in the headset and the stormscope inhibit" -- so I was curious if there was more to the story beyond trying the diodes.  Hopefully he still frequents this board and might remember...

[carusoam]

11 hours ago, bhardeman said:

Thanks.  I followed the diode theory, but the end of jetdriven's last post said "bad news, nothing changed, still the noise in the headset and the stormscope inhibit" -- so I was curious if there was more to the story beyond trying the diodes.  Hopefully he still frequents this board and might remember...

In that case... let’s invite Byron to stop by... @jetdriven.

Byron has a shop where he is working lots of hours... maintaining his excellent mechanic skills...  

Best regards,

-a-

[jetdriven]

5 minutes ago, carusoam said:

In that case... let’s invite Byron to stop by... @jetdriven.

Byron has a shop where he is working lots of hours... maintaining his excellent mechanic skills...  

Best regards,

-a-

Yesterday we pulled the lifters out of a TSIO360MB for a pre-buy. MB stands for Mo Betta.  It is a life-changingly better design. Everything a turbo six banger should be . Anyways you guys oughta consider an engine dehydrator because every lifter had corrosion on the  side and pitting on the face. This guy was lucky, it’s gonna roll on. But not all are lucky. 
 

So back to audio noise. I do not know if it’s the PMA8000BT audio panel, or the area  660 feeding into that is the problem. But here’s the thing, the newest gtn750 update has terrain advisory callous,  so you do not need an audio input from the aera 660 to the audio panel. So cutting that should Eliminate the ground loop noise perhaps. It’s noticeable, but very subtle. But it’s not gone.

[carusoam]

@bhardeman message came in from Byron for you...

-a-

[bhardeman]

@jetdriven Thanks.  I know this is an old thread, but I was wondering specifically about the stormscope inhibit issue.  Reading through the thread, you suspected that alternator noise was affecting the stormscope (since it stopped when turning off the alternator field) and tried to replace the diodes to fix.  But, the final post after the diode replacement was that nothing had changed.  Do you recall if the stormscope issue was ever figured out?

I just put on a brand new plane power alternator, and right after started getting stormscope inhibit errors.  It had worked fine for years before the new alternator.  Just looking for things to troubleshoot.  We have already tried cleaning and tightening all grounds.

With some extra searching, I did just find a post over on the beech forum from Aug 2016 by a Mooney owner.  Looks like that may have been from you also.  I will quote it below just to give some closure to this thread.  Let me know if you have anything else to add.  Maybe some Plane Power alternators are just noisier than average.

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My WX-1000 recently started giving an error 45, which is likely interference. Pulling the alternator field circuit breaker instantly restores it. So did turning some stuff off and lowering the electrical demand. I was able to duplicate it. I grounded the Stormscope processor to the negative battery cable, no change. Neither was changing the 2400uF noise capacitor on the main alternator power wire. I even swapped out the Plane Power alternator rectifier. Still have the original OECO voltage regulator. No change, still error 45 above ~30 amps of alternator load. This noise is above the audible range. Note I do not have an alternator filter capacitor mounted on the alternator, but the intercom is relatively free from electrical noise (strobes, landing gear an flap motors, etc).

So i did find a loose ground on the engine where it grounds to the firewall. I cleaned and tightened that up, and then I also ran the stormscope processor power and ground leads through a noise filter. That fixed it. I'm not sure which mod fixed it, but

It was high frequency AC noise from the alternator, in my case. it gets into the power buses and the airframe, and can freak the processor out.

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Edited February 6, 2021 by bhardeman

[jetdriven]

I still occasionally get error 45 storm scope inhibit. But since converting to LED Nav and strobes an LED Beacon, it lowers the the total amp draw, now it  basically stays below 30 amps which is what triggers this.

Edited February 6, 2021 by jetdriven