PlanePower shops?

[Raptor05121]

Starting a new thread seperate of my main one-

I've started to get static in my radios. Varying with engine speed. Small crackle at 2000rpm. 2500 is almost bearable. At 2700RPM its like white noise. On both radios. Engage PTT and it disappears- transmissions are clear. I've pulled the output post on the alternator and ran it up again- noise is gone.

I am not sure if its the brushes wearing out or a blown diode. Is there a shop I can send my alternator in for service? I've heard some auto shops can bench test it, would they be able to differentiate what the cause is versus "good" or "bad"?

[carusoam]

So far you got it down to the alternator....

Finding where they hide the diodes Is next...  the alternator manufacturer has the docs that show where they are...on board or in a separate box...

Burnt diodes sometimes look bad from the outside...

Testing their continuity isn’t too difficult either...

Getting them swapped out is a few cents for the diode...

And maybe some time for an electronics tech / AP.... solder and log....
 

Find out what diode part number is in there...

PP thoughts only, Got the experience form my plane’s tug.... /lawn tractor...
 

Best regards,

-a-

[N201MKTurbo]

I called them the other day to get a part number. Their tech support is very friendly and supportive. Don’t be afraid to call.

[Raptor05121]

23 hours ago, N201MKTurbo said:

I called them the other day to get a part number. Their tech support is very friendly and supportive. Don’t be afraid to call.

I e-mailed their service dept and got a reply back this morning from "Hartzell":

Hi Alex,

No we do not [have any repair shops] as there are no repairs approved except as recommended by ICA. You can check for diode failure by measuring AC voltage on the bus with a volt-ohmmeter. Brushes can be check per the online instructions under the Support/Installation heading. 

Regards,

Tim

Hartzell Engine Technologies

-------------------------------------

I don't quite understand their answer- they don't have any shops because no repairs are approved. But if I find the problem,  how do I get it repaired? I'd really like to not have to buy a new unit. I'm taking it to an auto shop in the morning and see if they can toss it on an oscilloscope.

[carusoam]

They're saying it isn’t hard to fix, and your mechanic is capable of doing it...  

Finding the bad diode(s) uses a ohm measuring device... measuring resistance....

My private pilot interpretation... not a mechanic...

Got a multimeter?

Best regards,

-a-

[Raptor05121]

Normally wouldn't be the case back home. I'm based at a large commercial/TSA airport where the only mechanic is an on-call mechanic for the airlines, and he charges A LOT. Trying to utilize him as little as possible, hence trying to send it out.

[J0nathan225]

2 minutes ago, Raptor05121 said:

Normally wouldn't be the case back home. I'm based at a large commercial/TSA airport where the only mechanic is an on-call mechanic for the airlines, and he charges A LOT. Trying to utilize him as little as possible, hence trying to send it out.

Interested if there is anything that can repair them, I may open it up myself. I have a bad diode plane power alt in my hanger, I would love to turn it into working bench stock. 

[jetdriven]

This is the rectifier for an AL12P70 plane power alternator.  Easy to swap. https://www.maniacelectricmotors.com/100mm-alternator-rectifier-denso-60-80-amp-8mm-post-inr720xhd.html

[Yetti]

Do you have a big noise filter on your firewall?

[carusoam]

There is a video included in Byron’s link... 

1) Use the video to identify all the parts... is it the same as your alternator?

2) For an A&P, not a really hard Job...

3) If you were back home you would be writing the story about how you got this signed off...   

+1 for The Yetti recommendation... checking the noise filter. Is it there, is it still connected properly.... and any other health checks possible for a giant capacitor...

Check if this is an airworthiness thing... it may be possible to fly it out from wherever you are to get it to a better place to have The work done...

A diode in an alternator is a typical failure that isn’t terrible... There are a few legs that will still be providing power... (Less power)... it just gets noisier (electronically) before it goes silent...

Ask your mechanic... or an MS mechanic... or your MS mechanic.... 

PP thoughts only, not a mechanic...

Best regards,

-a-

[jetdriven]

They are being very sneaky about their repairs.  They want to sell you a new one every time. The rectifier thing, it works. One thing I learned the hard way, is that a bad diode, the AC current ruins the battery. Then you have to buy new Concorde battery after 18 months. 

[EricJ]

The bit about checking with an ac voltmeter is to see whether a diode has failed.   If a diode fails one of the three phases won't contribute to the output and it'll make a big, periodic, divot in the output voltage.   That will show up as an ac component on the output.   If you put the meter in ac mode and sense a significant voltage, that's probably what's wrong.   If it is entirely DC, as it should be if everything is okay, the AC component will be zero or very small.

It's most obvious with an oscilloscope, but most people don't carry those around.

 

[RLCarter]

@Raptor05121 get with some of the locals and see who they are using for an A&P, check with the local EAA chapter as well, our piss ant chapter has several several A&P’s and an IA. 

[FloridaMan]

Also, slightly related. If your wiring is old, replace all of it, ideally to the battery, but at least everything in front of the firewall. You will have to do it eventually and it will likely ground you at some point when it’s inconvenient. It will cost you less to do it on your schedule and not when it fails completely. I had three alternator “failures” due to wires failing — two to the regulator and the other being the output wire. All three grounded me, and one of them resulted in a post maintenance engine failure that landed me in a field due to FOD. 

[Raptor05121]

Update- went to an auto stop, guy put it on a oscilloscope and says the rectifier is fine. I've found a local A&P, going to have him open it up and check the brushes.

No noise filter on the unit- although someone suggested I get one. I'd rather fix the cause than cover it with a bandaid.

[Raptor05121]

Brushes were fine. Got super frustrated so we reinstalled it. Cleaned some connections and BOOM. Problem gone. Go figure! Thanks for coming to my Ted Talk

[Skydancer2992]

30 minutes ago, Raptor05121 said:

Brushes were fine. Got super frustrated so we reinstalled it. Cleaned some connections and BOOM. Problem gone. Go figure! Thanks for coming to my Ted Talk

 

MInor Repair And CLEaning otherwise known as MIRACLE.

It only took a MIRACLE to eliminate the problem.

[carusoam]

Alex...

Where is your Ted talk..?

Got a link?

Best regards,

-a-

[tmo]

I thought this was his TED Talk...