Generators and Motors
[Home] - [HELP] - [Forums] - [Library] - [Photo Gallery] - [Groups] - [Classified Ads] - [Subscribe] - [Links] - [Books] - [Sponsors] -

Go Back   SmokStak > SmokStak® Vintage Electrical Equipment > Generators & Electric Motors General Discussion > Onan Generators
Forgot Password? Join Us!

Notices

Onan Generators Restoring, operating and maintaining vintage Onan generators.

Onan Generators

Rotating Diodes Checking


this thread has 32 replies and has been viewed 860 times

Reply
 
Thread Tools Display Modes
  #1  
Old 11-09-2017, 09:23:08 PM
EnginePat EnginePat is offline
Subscriber
 
Join Date: Aug 2011
Location: Connecticut
Posts: 458
Thanks: 232
Thanked 117 Times in 79 Posts
Smile Magniciter Diodes Checking

I was looking at a onan 12mdjc that the owner claims the rotating diodes are bad in it , he said a friend checked them and that's what's wrong with the machine. Could I please get schooled on the proper checking procedure.
Thanks

MODEL 12MDJC-3R/2268R
SPEC 0968061905
120/240 1 PHASE 50 AMP
06SX1N3B
12JC33N4C
__________________
Pat
5GO 3/RA
djc 4 cy done
jc 2 cyl runs

Last edited by EnginePat; 11-10-2017 at 12:34:36 AM. Reason: Wrong title
Reply With Quote
Sponsored Links
  #2  
Old 11-09-2017, 09:45:02 PM
Jim McIntyre's Avatar
Jim McIntyre Jim McIntyre is offline
Subscriber
 
Join Date: Nov 2004
Location: Mooresville, Indiana, USA
Posts: 3,869
Thanks: 632
Thanked 2,064 Times in 1,207 Posts
Default Re: Rotating diodes checking

This is a magniciter set, right? No rotating diodes in it.
Reply With Quote
The Following User Says Thank You to Jim McIntyre For This Post:
  #3  
Old 11-09-2017, 10:07:13 PM
BigBlockChev's Avatar
BigBlockChev BigBlockChev is offline
Subscriber
 
Join Date: Jan 2007
Location: Coquitlam, BC, Canada
Posts: 1,828
Thanks: 312
Thanked 1,350 Times in 794 Posts
Default Re: Rotating diodes checking

If that is the set in your post then I'm with Jim, if it is a different one let us know. Rotating diodes are a bit of a pain to check. They are covered in the YD gen end manual, but a certain amount of disassembly is required. Cheers Dan
__________________
It's always something simple.
One test is worth a thousand guesses.
If some is good and more is better then too much is just enough
Reply With Quote
The Following User Says Thank You to BigBlockChev For This Post:
  #4  
Old 11-09-2017, 10:11:30 PM
EnginePat EnginePat is offline
Subscriber
 
Join Date: Aug 2011
Location: Connecticut
Posts: 458
Thanks: 232
Thanked 117 Times in 79 Posts
Default Re: Rotating diodes checking (magniciter )

The Owner of the set said the diodes that were under the cover of the bell end were bad. I asumed they were the rotating diodes. Are there diodes in a magniciter end?
This is the set they may be in.
__________________
Pat
5GO 3/RA
djc 4 cy done
jc 2 cyl runs

Last edited by EnginePat; 11-10-2017 at 12:35:51 AM. Reason: Wrong title
Reply With Quote
  #5  
Old 11-09-2017, 10:48:33 PM
BigBlockChev's Avatar
BigBlockChev BigBlockChev is offline
Subscriber
 
Join Date: Jan 2007
Location: Coquitlam, BC, Canada
Posts: 1,828
Thanks: 312
Thanked 1,350 Times in 794 Posts
Default Re: Rotating diodes checking

Yes there are diodes under the endbell on a magneciter set, they are not rotating diodes , they can go and are not hard to replace , nor are they very expensive. There is a good thread in the stickys on magneciter theory and troubleshooting. It is long but enlightening. Cheers Dan

https://www.smokstak.com/forum/showthread.php?t=45741
__________________
It's always something simple.
One test is worth a thousand guesses.
If some is good and more is better then too much is just enough
Reply With Quote
The Following 3 Users Say Thank You to BigBlockChev For This Post:
  #6  
Old 11-09-2017, 10:50:12 PM
EnginePat EnginePat is offline
Subscriber
 
Join Date: Aug 2011
Location: Connecticut
Posts: 458
Thanks: 232
Thanked 117 Times in 79 Posts
Default diodes checking (magniciter )

Thanks Dan!
__________________
Pat
5GO 3/RA
djc 4 cy done
jc 2 cyl runs

Last edited by EnginePat; 11-10-2017 at 12:36:45 AM. Reason: Wrong title
Reply With Quote
  #7  
Old 11-09-2017, 10:57:03 PM
Vanman Vanman is offline
Subscriber
 
Join Date: Aug 2011
Location: Mission Viejo, California
Posts: 3,266
Thanks: 4,020
Thanked 1,351 Times in 907 Posts
Default Re: Rotating diodes checking

And make sure that you take a good look at those saturable reactors. Make sure they're a nice tan color and not burned. Seller could be trying to pass off bad reactors as bad diodes.
Reply With Quote
The Following User Says Thank You to Vanman For This Post:
  #8  
Old 11-09-2017, 10:59:45 PM
EnginePat EnginePat is offline
Subscriber
 
Join Date: Aug 2011
Location: Connecticut
Posts: 458
Thanks: 232
Thanked 117 Times in 79 Posts
Default Re: diodes checking (magniciter )

Right tan color good! Black ng!
__________________
Pat
5GO 3/RA
djc 4 cy done
jc 2 cyl runs

Last edited by EnginePat; 11-10-2017 at 12:37:44 AM. Reason: Wrong title
Reply With Quote
  #9  
Old 11-10-2017, 01:12:34 AM
pegasuspinto pegasuspinto is offline
Registered-III
 
Join Date: Oct 2006
Location: Floyd, AR, USA
Posts: 2,527
Thanks: 319
Thanked 1,160 Times in 763 Posts
Default Re: Rotating Diodes Checking

REALLY REALLY simple to toss the magnecitor regulator and pop in a Power-Tronics unit. Works quite well. Assuming the rest of the set is OK I wouldn't worry much about the magnecitor being bad.
Reply With Quote
The Following User Says Thank You to pegasuspinto For This Post:
  #10  
Old 11-10-2017, 02:27:22 AM
Vanman Vanman is offline
Subscriber
 
Join Date: Aug 2011
Location: Mission Viejo, California
Posts: 3,266
Thanks: 4,020
Thanked 1,351 Times in 907 Posts
Default Re: Rotating Diodes Checking

You could do that, but you would be replacing a few rugged possible points of failure with what, hundreds? thousands? Of delicate points of failure. Better to just buy a YD generator equipped set in the first place, and keep a few spare regulators on hand.
Reply With Quote
The Following User Says Thank You to Vanman For This Post:
  #11  
Old 11-10-2017, 08:57:37 AM
EnginePat EnginePat is offline
Subscriber
 
Join Date: Aug 2011
Location: Connecticut
Posts: 458
Thanks: 232
Thanked 117 Times in 79 Posts
Default Re:diodes checking (magniciter )

I know where I can get used magniciters, but I would have to make sure the numbers are the same. They swap all the onans that come in to power-tronics.
__________________
Pat
5GO 3/RA
djc 4 cy done
jc 2 cyl runs

Last edited by EnginePat; 11-10-2017 at 01:54:22 PM.
Reply With Quote
  #12  
Old 11-10-2017, 12:26:40 PM
turtmaster turtmaster is offline
Registered-I
 
Join Date: Jun 2015
Location: Hortonville, Wisconsin
Posts: 244
Thanks: 172
Thanked 69 Times in 43 Posts
Default Re: diodes checking (magniciter )

any particular reason that they swap them over?
Reply With Quote
  #13  
Old 11-10-2017, 12:44:29 PM
Jim McIntyre's Avatar
Jim McIntyre Jim McIntyre is offline
Subscriber
 
Join Date: Nov 2004
Location: Mooresville, Indiana, USA
Posts: 3,869
Thanks: 632
Thanked 2,064 Times in 1,207 Posts
Default Re: Rotating Diodes Checking

^ the magniciters lost their magic smoke?
Reply With Quote
  #14  
Old 11-10-2017, 01:20:36 PM
Kevin K Kevin K is offline
Registered-III
 
Join Date: Jan 2005
Location: upstate New York USA
Posts: 3,521
Thanks: 3,156
Thanked 3,506 Times in 1,904 Posts
Default Re: Rotating Diodes Checking

^ No one in the shop understands Magneciters, so it's easier to swap in a Power-tronics regulator?
Reply With Quote
  #15  
Old 11-10-2017, 01:56:01 PM
EnginePat EnginePat is offline
Subscriber
 
Join Date: Aug 2011
Location: Connecticut
Posts: 458
Thanks: 232
Thanked 117 Times in 79 Posts
Default Re: diodes checking (magniciter )

The shop that has the used ones told me they just change all of them that come in, they said they scrap them all.
__________________
Pat
5GO 3/RA
djc 4 cy done
jc 2 cyl runs
Reply With Quote
  #16  
Old 11-10-2017, 02:02:58 PM
pegasuspinto pegasuspinto is offline
Registered-III
 
Join Date: Oct 2006
Location: Floyd, AR, USA
Posts: 2,527
Thanks: 319
Thanked 1,160 Times in 763 Posts
Default Re: Rotating Diodes Checking

They are old, obsolete, failure prone, expensive as hell, hard to understand for a lot of people?

Besides, who would describe a power-tronics unit as fragile?
Reply With Quote
  #17  
Old 11-10-2017, 02:22:16 PM
len k len k is online now
Registered-III
 
Join Date: Jun 2012
Location: Manchester, New Hampshire
Posts: 14,720
Thanks: 389
Thanked 5,321 Times in 3,874 Posts
Default Re: Rotating Diodes Checking

Quote:
Originally Posted by Kevin K View Post
^ No one in the shop understands Magneciters, so it's easier to swap in a Power-tronics regulator?
The dumbing down of America, pull good reliable equipment and replace with China junk. We're doomed.....
Reply With Quote
The Following 2 Users Say Thank You to len k For This Post:
  #18  
Old 11-10-2017, 02:32:21 PM
EnginePat EnginePat is offline
Subscriber
 
Join Date: Aug 2011
Location: Connecticut
Posts: 458
Thanks: 232
Thanked 117 Times in 79 Posts
Default Re: Rotating Diodes Checking

Power tronics parts are not free, xr8 vr, $396. And sem250a $237.
__________________
Pat
5GO 3/RA
djc 4 cy done
jc 2 cyl runs
Reply With Quote
  #19  
Old 11-10-2017, 02:57:48 PM
Birken Vogt Birken Vogt is offline
Email NOT Working
 
Join Date: Sep 2009
Location: Penn Valley, California, USA
Posts: 1,480
Thanks: 2
Thanked 463 Times in 329 Posts
Default Re: Rotating Diodes Checking

Any unit with a magenciter is far too old to consider reliable power for anything. All the other components are old and rotten waiting to break, even the windings and varnish and such.

Sure they are fun as a hobby but this stuff has a finite lifespan until it becomes just too old.

The mistake people make is buying new junk to replace old quality. New quality is what they should have gotten.
Reply With Quote
The Following User Says Thank You to Birken Vogt For This Post:
  #20  
Old 11-10-2017, 04:06:48 PM
Vanman Vanman is offline
Subscriber
 
Join Date: Aug 2011
Location: Mission Viejo, California
Posts: 3,266
Thanks: 4,020
Thanked 1,351 Times in 907 Posts
Default Re: diodes checking (magniciter )

Quote:
Originally Posted by EnginePat View Post
The shop that has the used ones told me they just change all of them that come in, they said they scrap them all.
Typical moron mentality. Even though superior elegant simplicity is staring them right in the face, they destroy it in favor of crap because it's easier than actually learning about what they're working on. Not technicians, parts swappers.

I do not entirely agree that old alone qualifies something as unreliable. More like the number of operating hours. But even that alone does not quantify the life of such things as electrical insulating varnish. Seems that the majority of generators spend most of their operating hours at well below rated load. As insulation temperature decreases, insulation life approaches infinity.
Reply With Quote
The Following User Says Thank You to Vanman For This Post:
Reply


Thread Tools
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

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

F o r u m Jump

Similar Threads Chosen at Random
Thread Thread Starter F o r u m Replies Last Post
What happens if you have a blown rotating diode BigBlockChev Onan Generators 6 07-19-2015 08:36:59 PM
Rotating Throttle Repair? GreasyIron Steam Stationary Engines, Traction Engines, Steam Boats 22 09-23-2014 11:27:59 AM
Wisconsin VF4 rotating assembly ? GrumpyBobby Wisconsin Engines 4 05-03-2013 09:26:30 AM
MEP-16A Rotating Diode? K D Redd Military MEP and Aircraft Gen-Sets 3 08-19-2008 12:19:28 AM


Use "Ctrl" mouse wheel to change screen size.
All times are GMT -4. The time now is 05:01:22 PM.

Smokstak and Enginads site search!


All use is subject to our TERMS OF SERVICE
SMOKSTAK® is a Registered Trade Mark - A Community of Antique Engine Enthusiasts
Copyright © 2000 - 2016 by Harry Matthews P.O. Box 5612 - Sarasota, FL 34277