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Onan Bridge Rectifier replacement - wiring help [message #193429]

Thu, 20 December 2012 10:51

75realsteel

Messages: 26
Registered: December 2012
Location: Chicago

Karma: 0

Junior Member

Hi All -
I'm new to the forum after having purchased a 75 EleganzaII a few months back. Thanks to all for creating a great repository of helpful information!

I'm in the process of getting my Onan 6K up and running. After replacing the control board, she fired up and ran just fine. I was getting AC at the outlets for a short time before it cut out, so I decided to first change the Bridge Rectifier. While trying to get the old BR out, one of the wires which connect to the "AC" plug on the BR came loose from the Onan and I'm not exactly sure where it came loose from. I'd rather get some feedback from folks who know before causing further problems Smile

The wire in question is shown here - it's the shorter white "AC" wire:
http://www.gmcmhphotos.com/photos/onan/p46845-bridge-rectifier-holder-removed.html

I'm guessing it attaches to one of the bottom brush leads shown here:
http://www.gmcmhphotos.com/photos/onan/p46846-bottom-brush.html

The other "AC" lead is a longer black wire - it's shown here for completeness:
http://www.gmcmhphotos.com/photos/onan/p46847-bridge-rectifier-removed.html

thanks for any help -
Kevin

'77 Kingsley 26 - Chicago, IL

[Updated on: Thu, 20 December 2012 10:52]

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Re: [GMCnet] Onan Bridge Rectifier replacement - wiring help [message #193438 is a reply to message #193429]

Thu, 20 December 2012 12:21

emerystora

Messages: 4442
Registered: January 2004

Karma: 13

Senior Member

On Dec 20, 2012, at 9:51 AM, Kevin wrote:

>
>
> Hi All -
> I'm new to the forum after having purchased a 75 EleganzaII a few months back. Thanks to all for creating a great repository of helpful information!
>
> I'm in the process of getting my Onan 6K up and running. After replacing the control board, she fired up and ran just fine. I was getting AC at the outlets for a short time before it cut out, so I decided to first change the Bridge Rectifier. While trying to get the old BR out, one of the wires which connect to the "AC" plug on the BR came loose from the Onan and I'm not exactly sure where it came loose from. I'd rather get some feedback from folks who know before causing further problems :)
>
> The wire in question is shown here - it's the shorter white "AC" wire:
>
>
> I'm guessing it attaches to one of the bottom brush leads shown here:
>
>
> The other "AC" lead is a longer black wire - it's shown here for completeness:
>
>

Kevin

I don't see any pictures but I know where the wires go. Look for a plastic tube and you'll find the other end of the connector in it. It doesn't go to the brushes but rather it goes to the field windings.

There are two male/female spade connectors going from the field windings to the + and -
terminals of the rectifier. Each set is in its own approximately 2"
plastic insulating tube. The connectors are made of brass and often is loose and has s very poor contact as the brass female connector loses
its tension. I once attempted to squeeze it with some needle nose pliers
and it immediately cracked. I then soldered in a new steel female
connector, coated it with dielectric grease and plugged it back in to
the male connector in the tube. I checked the other connector and
found that it also was making very poor connection and was also loose
in the tube. I replaced that connector as well.

Emery Stora
77 Kingsley
Frederick, CO
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Re: [GMCnet] Onan Bridge Rectifier replacement - wiring help [message #193440 is a reply to message #193429]

Thu, 20 December 2012 13:05

Mr ERFisher

Messages: 7117
Registered: August 2005

Karma: 2

Senior Member

this might help

http://www.gmcmhphotos.com/photos/onan-bridge-rectifier-replacement/p3472.html
and
http://gmcmotorhome.info/generator.html#bridge
and
http://www.bdub.net/manuals/onanmanual.pdf
page 30

good luck
gene

On Thu, Dec 20, 2012 at 8:51 AM, Kevin <75realsteel@gmail.com> wrote:

>
>
> Hi All -
> I'm new to the forum after having purchased a 75 EleganzaII a few months
> back. Thanks to all for creating a great repository of helpful information!
>
> I'm in the process of getting my Onan 6K up and running. After replacing
> the control board, she fired up and ran just fine. I was getting AC at the
> outlets for a short time before it cut out, so I decided to first change
> the Bridge Rectifier. While trying to get the old BR out, one of the wires
> which connect to the "AC" plug on the BR came loose from the Onan and I'm
> not exactly sure where it came loose from. I'd rather get some feedback
> from folks who know before causing further problems :)
>
> The wire in question is shown here - it's the shorter white "AC" wire:
>
>
> I'm guessing it attaches to one of the bottom brush leads shown here:
>
>
> The other "AC" lead is a longer black wire - it's shown here for
> completeness:
>
>
> thanks for any help -
> Kevin
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>

--
Gene Fisher -- 74-23,77PB/ore/ca
�Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
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Re: [GMCnet] Onan Bridge Rectifier replacement - wiring help [message #193480 is a reply to message #193429]

Thu, 20 December 2012 19:49

powerjon

Messages: 2446
Registered: January 2004

Karma: 5

Senior Member

Kevin,
If you post pictures on the forum they do not get transferred to the GMC Net. Most use the GMC photo site and post pictures there.

http://www.gmcmhphotos.com/photos/help.html

JR Wright
78 Buskirk Stretch
Michigan

On Dec 20, 2012, at 11:51 AM, Kevin <75realsteel@gmail.com> wrote:

>
>
> Hi All -
> I'm new to the forum after having purchased a 75 EleganzaII a few months back. Thanks to all for creating a great repository of helpful information!
>
> I'm in the process of getting my Onan 6K up and running. After replacing the control board, she fired up and ran just fine. I was getting AC at the outlets for a short time before it cut out, so I decided to first change the Bridge Rectifier. While trying to get the old BR out, one of the wires which connect to the "AC" plug on the BR came loose from the Onan and I'm not exactly sure where it came loose from. I'd rather get some feedback from folks who know before causing further problems :)
>
> The wire in question is shown here - it's the shorter white "AC" wire:
>
>
> I'm guessing it attaches to one of the bottom brush leads shown here:
>
>
> The other "AC" lead is a longer black wire - it's shown here for completeness:
>
>
> thanks for any help -
> Kevin
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J.R. Wright
GMC GreatLaker
GMC Eastern States
GMCMI
78 30' Buskirk Stretch
75 Avion Under Reconstruction
Michigan

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Re: [GMCnet] Onan Bridge Rectifier replacement - wiring help [message #193492 is a reply to message #193429]

Thu, 20 December 2012 21:06

Billy Massey

Messages: 916
Registered: January 2004
Location: Central Texas

Karma: 1

Senior Member

Ref:
http://www.gmcmhphotos.com/photos/g6257-onan.html

-----Original Message-----
From: On Behalf Of Kevin
Sent: Thursday, December 20, 2012 10:52 AM

I'm in the process of getting my Onan 6K up and running. After replacing
the control board, she fired up and ran just fine. I was getting AC at the
outlets for a short time before it cut out, so I decided to first change the
Bridge Rectifier. While trying to get the old BR out, one of the wires
which connect to the "AC" plug on the BR came loose from the Onan and I'm
not exactly sure where it came loose from. I'd rather get some feedback
from folks who know before causing further problems :)

The wire in question is shown here - it's the shorter white "AC" wire:

I'm guessing it attaches to one of the bottom brush leads shown here:

The other "AC" lead is a longer black wire - it's shown here for
completeness:

thanks for any help -
Kevin

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bdub
bdub.net

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Re: [GMCnet] Onan Bridge Rectifier replacement - wiring help [message #194330 is a reply to message #193492]

Sat, 29 December 2012 13:02

75realsteel

Messages: 26
Registered: December 2012
Location: Chicago

Karma: 0

Junior Member

Hi, thanks for the replies. I think I fixed my first post to include the images properly, please advise if I am still uploading pictures incorrectly, though.

I uploaded a picture of the remaining wires for clarity:
http://www.gmcmhphotos.com/photos/onan/p46892-bridge-rectifier-remaining-wires.html

The wire that is not connected is the short white one that goes to one of the "AC" terminals as shown here:
http://www.gmcmhphotos.com/photos/onan/p46845-bridge-rectifier-holder-removed.html

The "+" and "-" wires Emory referred to are still properly attached inside the plastic tubes.

If anyone has any clue where this 4th wire goes, I'd very much appreciate it. I believe it goes to one of the connectors I've marked on this image - perhaps all of these connectors are essentially the same (I suppose I could verify that with an ohm-meter).
http://www.gmcmhphotos.com/photos/onan/p46846-bottom-brush.html

thanks for any help,
Hope the pictures are now viewable.
Kevin

'77 Kingsley 26 - Chicago, IL

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Re: Onan Bridge Rectifier replacement - wiring help [message #194350 is a reply to message #193429]

Sat, 29 December 2012 20:15

mike miller

Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon

Karma: 0

Senior Member

75realsteel wrote on Thu, 20 December 2012 08:51

Kevin,

I think you'll need to trace some wires.

If you look at figure 57 in the Onan NH (6k) Service Manual (you can find it on the DVD or bdub's site) you'll see that one of the rectifier AC inputs comes from the thyrector (a bead like object in the harness near the transformer in the upper corner on the Bell.

http://www.gmcmhphotos.com/photos/data/3694/694_p16880.jpg

That transformer is fed power from one set of brushes and outputs power to the circuit breaker.

For your lost connection, you are looking for the OTHER set of brushes. That set of brushes is the other side of the AC fed to the AC load and the second AC input to your rectifier.

Happy Onan'N! Smile

Mike Miller -- Hillsboro, OR -- on the Black list
(#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
More Sidekicks than GMC's and a late model Malibu called 'Boo' http://m000035.blogspot.com

[Updated on: Sat, 29 December 2012 20:19]

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