VansAirForceForums  
Home > VansAirForceForums

-POSTING RULES
-Advertise in here!
- Today's Posts | Insert Pics

Keep VAF Going
Donate methods

Point your
camera app here
to donate fast.


Go Back   VAF Forums > Avionics / Interiors / Fiberglass > Electrical Systems
Register FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
  #41  
Old 03-09-2021, 06:01 AM
carlrai's Avatar
carlrai carlrai is offline
 
Join Date: May 2005
Posts: 513
Default Had similar experience

[quote=Noah;1508603]Thanks Bill. Some good thoughts there.

I removed my diode pack and flipped it over. Here's what it looked like. Thoughts? The stator field wires all seemed intact, none broken there.



Similar experience with the diode stack on my PP. Replaced with this - Restored and working fine.

Replacement Diode Stack
__________________
Carl Raichle
Lutz, FL
RV-9A N194CR
RV-14A Under construction
Based at KZPH
AA4SR
Reply With Quote
  #42  
Old 03-09-2021, 06:44 AM
DanH's Avatar
DanH DanH is offline
 
Join Date: Oct 2005
Location: 08A
Posts: 9,934
Default

Quote:
Originally Posted by Noah View Post
I removed my diode pack and flipped it over. Here's what it looked like. Thoughts?
Seems like the B-lead post has been subject to vibration. Too much hanging wire?
__________________
Dan Horton
RV-8 SS
Barrett IO-390
Reply With Quote
  #43  
Old 03-09-2021, 09:44 AM
Noah's Avatar
Noah Noah is offline
 
Join Date: Jun 2007
Location: Rhode Island
Posts: 947
Default

Quote:
Originally Posted by DanH View Post
Seems like the B-lead post has been subject to vibration. Too much hanging wire?
Yes, it sure does look like it from the cracks in the rectifier, doesn't it? Curious, since my B-Lead was secured to the cover with a large zip tie about 2-3 inches from the B-Terminal so any vibration would be limited to a direction along the axis of the B-Lead.

Quote:
Originally Posted by carlrai View Post
Similar experience with the diode stack on my PP. Replaced with this - Restored and working fine. Replacement Diode Stack
Thanks!

My engine monitor records all parameters once per second but never recorded a voltage spike, yet my field breaker tripped. If there are voltage spikes, are they likely to be incredibly short duration events, so that the engine monitor is unlikely to catch them even at its fastest recording rate of 1/s? Or are there other VR failure modes (unrelated to overvoltage) that would cause the field breaker to trip? Would a cracked/intermittent rectifier lead to overvoltage & crowbar shutdown via field breaker trip?

Is there any documentation available regarding bench test procedures for these alternators? I couldn't find one on PP's website. I brought this to an auto parts store to test but they couldn't do it since their test setup requires a vehicle make & model, and the regulator is modified by PP so the electrical connections are altered. Maybe going to a real alternator shop instead of a parts store is the key?

My tension arm bracket is also cracked so I'm looking for one of those if anyone has one available...
__________________
Highest Regards,

Noah F, RV-7A

All men dream, but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find that it was vanity: but the dreamers of the day are dangerous men, for they may act their dream with open eyes, to make it possible. -T.E. Lawrence
Reply With Quote
  #44  
Old 03-09-2021, 12:14 PM
bjdecker's Avatar
bjdecker bjdecker is offline
 
Join Date: Jun 2005
Location: Georgetown, TX
Posts: 603
Default Cracks...

Maybe not the "B" lead flopping around but an out of balance pulley, rotor or both - you can spin it up to a few thousand RPM and feel the vibration if that's the case.
__________________
Brian Decker
Retired Firmware Guy and Airplane Builder

2020 RV-14 QB -- Under construction - Tailcone & Empennage Complete.
2018 RV-7 QB -- Built, Flying
2007 RV-7 QB -- Built, Drowned, Resurrected and flying
1998 RV-8 QB -- Started, Sold
1986 Mooney 205SE
1980 Mooney 231

Aided and abetted building a number of other RV's.
Reply With Quote
  #45  
Old 03-09-2021, 01:42 PM
BillL BillL is online now
 
Join Date: Sep 2007
Location: Central IL
Posts: 5,873
Default

Quote:
Originally Posted by Noah View Post
Thanks Bill. Some good thoughts there.



Where did you find a test procedure for this alternator? I could not find one.
Can you post a picture of the bearing on the slip ring end of the rotor? This could be critical to your ability to complete the rebuild. This end bearing is a whole new subject in itself.

I tested a PP with a fried diode and the voltage was low and drawing high amps from the field to try and reach output voltage.

Look at the circuit diagram on page 6. Note that the rotor has one leg attached to the B lead (+12v). The PP has that connection as external i.e field wire. Now, Locate F and note that you can ground it to give the field full raw 12DCV power. That would drive up the voltage and let you know that the alternator can make power. The regulator controls the output voltage vis the ground side.

A moot point on the diode bridge now, as you really need one.

Here is the test procedure. Click and save as . . .

Click image for larger version

Name:	Toyota Alternator testing.pdf
Views:	67
Size:	849.6 KB
ID:	9193
__________________
Bill

RV-7
Lord Kelvin:
I often say that when you can measure what you are speaking about,
and express it in numbers, you know something about it; but when you
cannot measure it, when you cannot express it in numbers, your knowledge
is of a meager and unsatisfactory kind.
Reply With Quote
  #46  
Old 03-10-2021, 08:49 PM
Noah's Avatar
Noah Noah is offline
 
Join Date: Jun 2007
Location: Rhode Island
Posts: 947
Default

Thanks for the test procedure and diagnostic info Bill, very helpful! I also found this video for troubleshooting and bench testing one of these alternators:
https://youtu.be/at_R7sENE0s

Incidentally testing my cracked rectifier showed that all diodes were good but since my problem is intermittent that shouldn't be too surprising that it seems fine. I'm hoping that replacing it will correct my issue.

Quote:
Originally Posted by BillL View Post
Can you post a picture of the bearing on the slip ring end of the rotor?
I have not opened up the case to get a look at the bearings since mine feel fine but I'll snap a photo if I do.
__________________
Highest Regards,

Noah F, RV-7A

All men dream, but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find that it was vanity: but the dreamers of the day are dangerous men, for they may act their dream with open eyes, to make it possible. -T.E. Lawrence
Reply With Quote
  #47  
Old 03-11-2021, 04:35 PM
jdeas's Avatar
jdeas jdeas is offline
 
Join Date: Mar 2006
Location: SoCal
Posts: 633
Default 2nd

Quote:
Originally Posted by lr172 View Post
It seems the common failure for these alternators is broken wires on the stator. May want to give a look inside before modifying the VR. Several posts on the subject.

Larry

Replaced a regulator board once when one of the three stator windings broke. Didn't fix it and didn't see the real problem until the 2nd wire broke as well killing all output
__________________
JD
----------------------
RV-7 N314SY (KWHP)
IO-360-B1B
A&P


CANbus based trim/flaps and electrical
Reply With Quote
  #48  
Old 03-21-2021, 07:27 PM
Noah's Avatar
Noah Noah is offline
 
Join Date: Jun 2007
Location: Rhode Island
Posts: 947
Default

New rectifier assembly seems to have fixed my popping field breaker issue. Test flight today and all is well.
__________________
Highest Regards,

Noah F, RV-7A

All men dream, but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find that it was vanity: but the dreamers of the day are dangerous men, for they may act their dream with open eyes, to make it possible. -T.E. Lawrence
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 04:13 PM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.