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Home » Public Forums » GMCnet » 4K Onan Bridge Rectifier (Can you get to it without removing the generator?)
4K Onan Bridge Rectifier [message #307130] Wed, 14 September 2016 14:35 Go to next message
timthenomad   United States
Messages: 63
Registered: June 2015
Location: Austin, TX
Karma: 5
Member
Hi All,

The 4K Onan in my Birchaven stopped producing AC current recently. After reading a lot of old posts, it seems there's a good chance it is the bridge rectifier. So I ordered up one of the newer "twist the pins" replacements. I have downloaded the manual and the schematics show where is relatively, but don't seem to offer much in terms of how one is to get at it.

Can I do the R&R with the generator still in the coach?

Thanks

Tim


Tim Taylor
Austin TX
Philadelphia PA
76 Birchaven (SB)
76 Triumph TR6
Re: [GMCnet] 4K Onan Bridge Rectifier [message #307132 is a reply to message #307130] Wed, 14 September 2016 14:53 Go to previous messageGo to next message
jimk is currently offline  jimk   United States
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
Senior Member
Just pop off the plastic grill.
Call me and I'll walk you through.

On Wed, Sep 14, 2016 at 12:35 PM, Tim Taylor wrote:

> Hi All,
>
> The 4K Onan in my Birchaven stopped producing AC current recently. After
> reading a lot of old posts, it seems there's a good chance it is the bridge
> rectifier. So I ordered up one of the newer "twist the pins"
> replacements. I have downloaded the manual and the schematics show where
> is relatively,
> but don't seem to offer much in terms of how one is to get at it.
>
> Can I do the R&R with the generator still in the coach?
>
> Thanks
>
> Tim
> --
> Tim Taylor
> Austin TX
> 76 Birchaven (SB)
> 76 Triumph TR6
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>



--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
Re: [GMCnet] 4K Onan Bridge Rectifier [message #307133 is a reply to message #307132] Wed, 14 September 2016 15:58 Go to previous messageGo to next message
Mr ERFisher is currently offline  Mr ERFisher   United States
Messages: 7117
Registered: August 2005
Karma: 2
Senior Member
Read here
http://gmcmotorhome.info/generator.html#bridge



On Wednesday, September 14, 2016, Jim Kanomata
wrote:

> Just pop off the plastic grill.
> Call me and I'll walk you through.
>
> On Wed, Sep 14, 2016 at 12:35 PM, Tim Taylor > wrote:
>
>> Hi All,
>>
>> The 4K Onan in my Birchaven stopped producing AC current recently. After
>> reading a lot of old posts, it seems there's a good chance it is the
> bridge
>> rectifier. So I ordered up one of the newer "twist the pins"
>> replacements. I have downloaded the manual and the schematics show where
>> is relatively,
>> but don't seem to offer much in terms of how one is to get at it.
>>
>> Can I do the R&R with the generator still in the coach?
>>
>> Thanks
>>
>> Tim
>> --
>> Tim Taylor
>> Austin TX
>> 76 Birchaven (SB)
>> 76 Triumph TR6
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
>
>
>
> --
> Jim Kanomata
> Applied/GMC, Fremont,CA
> jimk@appliedairfilters.com
> http://www.appliedgmc.com
> 1-800-752-7502
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>


--
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: 4K Onan Bridge Rectifier [message #307140 is a reply to message #307130] Wed, 14 September 2016 18:08 Go to previous messageGo to next message
Matt Colie is currently offline  Matt Colie   United States
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
Senior Member
Tim,

In spite of what has been posted, do not be surprised if you can not get at it. It may be different in later BFs, but in my 73 - 23 it can not be done. I also have a real struggle to get the cover off the control board.

I suggest that you get the older manual that covers the BF (4.0) X7425. It can be downloaded. Removal of a BF is different than a NH(6.0) and if you try to do it that way, you will end up in a bind.

You do not need to fully disconnect the unit, just the supporting mounts need be set loose so you can pull the BF clear of the coach and make access to the bridge simple.

Matt



timthenomad wrote on Wed, 14 September 2016 15:35
Hi All,

The 4K Onan in my Birchaven stopped producing AC current recently. After reading a lot of old posts, it seems there's a good chance it is the bridge rectifier. So I ordered up one of the newer "twist the pins" replacements. I have downloaded the manual and the schematics show where is relatively, but don't seem to offer much in terms of how one is to get at it.

Can I do the R&R with the generator still in the coach?

Thanks

Tim



Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
Re: 4K Onan Bridge Rectifier [message #307147 is a reply to message #307140] Wed, 14 September 2016 18:34 Go to previous messageGo to next message
Dennis S is currently offline  Dennis S   United States
Messages: 3046
Registered: November 2005
Karma: 2
Senior Member
The early coaches varied a lot - my 73, 23 ft is earlier production than Matt's but I had no real problem removing the rectifier for testing.
Just be aware of debris falling into eyes/face.

Dennis

Matt Colie wrote on Wed, 14 September 2016 18:08
Tim,

In spite of what has been posted, do not be surprised if you can not get at it. It may be different in later BFs, but in my 73 - 23 it can not be done. I also have a real struggle to get the cover off the control board.

I suggest that you get the older manual that covers the BF (4.0) X7425. It can be downloaded. Removal of a BF is different than a NH(6.0) and if you try to do it that way, you will end up in a bind.

You do not need to fully disconnect the unit, just the supporting mounts need be set loose so you can pull the BF clear of the coach and make access to the bridge simple.

Matt



timthenomad wrote on Wed, 14 September 2016 15:35
Hi All,

The 4K Onan in my Birchaven stopped producing AC current recently. After reading a lot of old posts, it seems there's a good chance it is the bridge rectifier. So I ordered up one of the newer "twist the pins" replacements. I have downloaded the manual and the schematics show where is relatively, but don't seem to offer much in terms of how one is to get at it.

Can I do the R&R with the generator still in the coach?

Thanks

Tim




Dennis S
73 Painted Desert 230
Memphis TN Metro
Re: 4K Onan Bridge Rectifier [message #307149 is a reply to message #307130] Wed, 14 September 2016 18:53 Go to previous messageGo to next message
rjw   United States
Messages: 697
Registered: September 2005
Karma: 4
Senior Member
timthenomad wrote on Wed, 14 September 2016 15:35
Hi All,

The 4K Onan in my Birchaven stopped producing AC current recently. After reading a lot of old posts, it seems there's a good chance it is the bridge rectifier. So I ordered up one of the newer "twist the pins" replacements. I have downloaded the manual and the schematics show where is relatively, but don't seem to offer much in terms of how one is to get at it.

Can I do the R&R with the generator still in the coach?

Thanks

Tim

I just did the bridge rectifier in my 6KW Onan and it is a tight fit, but doable. We did my neighbors 4KW a few years ago and that was also a tight fit but doable. You need to make sure and mark the + and - wires and where they go as well as both AC wires and where they go. The new bridge rectifiers are a different pin configuration from what came from the factory. I modified and kept the plastic holder.

I was happy that the cause of my losing AC power to run my roof air during the Woodward Dream Cruise was the bridge and not something other then the failure of the 41 year old rectifier.



Richard
76 Palm Beach
SE Michigan
www.PalmBeachGMC.com

Roller Cam 455, TBI+EBL, 3.42 FD, 4 Bag, Macerator, Lenzi (brakes, vacuum system, front end stuff), Manny Tranny, vacuum step, Tankless + OEM water heaters.
Re: [GMCnet] 4K Onan Bridge Rectifier [message #307154 is a reply to message #307140] Wed, 14 September 2016 19:04 Go to previous messageGo to next message
Mike Kilroy is currently offline  Mike Kilroy   United States
Messages: 80
Registered: July 2006
Location: Farmersville, OH (near D...
Karma: 0
Member
I replaced mine in the coach ok. 73 model too.

----- Original Message -----
From: "Matt Colie"
To: gmclist@list.gmcnet.org
Sent: Wednesday, September 14, 2016 7:08:51 PM
Subject: Re: [GMCnet] 4K Onan Bridge Rectifier

Tim,

In spite of what has been posted, do not be surprised if you can not get at it. It may be different in later BFs, but in my 73 - 23 it can not be
done. I also have a real struggle to get the cover off the control board.

I suggest that you get the older manual that covers the BF (4.0) X7425. It can be downloaded. Removal of a BF is different than a NH(6.0) and if you
try to do it that way, you will end up in a bind.

You do not need to fully disconnect the unit, just the supporting mounts need be set loose so you can pull the BF clear of the coach and make access
to the bridge simple.

Matt



timthenomad wrote on Wed, 14 September 2016 15:35
> Hi All,
>
> The 4K Onan in my Birchaven stopped producing AC current recently. After reading a lot of old posts, it seems there's a good chance it is the
> bridge rectifier. So I ordered up one of the newer "twist the pins" replacements. I have downloaded the manual and the schematics show where is
> relatively, but don't seem to offer much in terms of how one is to get at it.
>
> Can I do the R&R with the generator still in the coach?
>
> Thanks
>
> Tim


--
Matt & Mary Colie - Members GMCMI, GMCGL, GMCES
'73 Glacier 23 - Still Loving OE Rear Drum Brake with Applied Control Arms
Now with both true Keyless and remote entry
SE Michigan - Twixt A2 and Detroit

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Mike (AC8V) & Vickie Kilroy
'73 Canyon Land 26' sidebath
455/ceramic filled crossovers
Re: [GMCnet] 4K Onan Bridge Rectifier [message #307170 is a reply to message #307154] Wed, 14 September 2016 22:24 Go to previous messageGo to next message
jimk is currently offline  jimk   United States
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
Senior Member
We have done the 4k and 6k the same way.
Never need to dismount the unit.

On Wed, Sep 14, 2016 at 5:04 PM, Mike Kilroy wrote:

> I replaced mine in the coach ok. 73 model too.
>
> ----- Original Message -----
> From: "Matt Colie"
> To: gmclist@list.gmcnet.org
> Sent: Wednesday, September 14, 2016 7:08:51 PM
> Subject: Re: [GMCnet] 4K Onan Bridge Rectifier
>
> Tim,
>
> In spite of what has been posted, do not be surprised if you can not get
> at it. It may be different in later BFs, but in my 73 - 23 it can not be
> done. I also have a real struggle to get the cover off the control board.
>
> I suggest that you get the older manual that covers the BF (4.0) X7425.
> It can be downloaded. Removal of a BF is different than a NH(6.0) and if
> you
> try to do it that way, you will end up in a bind.
>
> You do not need to fully disconnect the unit, just the supporting mounts
> need be set loose so you can pull the BF clear of the coach and make access
> to the bridge simple.
>
> Matt
>
>
>
> timthenomad wrote on Wed, 14 September 2016 15:35
>> Hi All,
>>
>> The 4K Onan in my Birchaven stopped producing AC current recently.
> After reading a lot of old posts, it seems there's a good chance it is the
>> bridge rectifier. So I ordered up one of the newer "twist the pins"
> replacements. I have downloaded the manual and the schematics show where is
>> relatively, but don't seem to offer much in terms of how one is to get
> at it.
>>
>> Can I do the R&R with the generator still in the coach?
>>
>> Thanks
>>
>> Tim
>
>
> --
> Matt & Mary Colie - Members GMCMI, GMCGL, GMCES
> '73 Glacier 23 - Still Loving OE Rear Drum Brake with Applied Control Arms
> Now with both true Keyless and remote entry
> SE Michigan - Twixt A2 and Detroit
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>



--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
Re: 4K Onan Bridge Rectifier [message #307172 is a reply to message #307140] Thu, 15 September 2016 03:19 Go to previous message
rjw   United States
Messages: 697
Registered: September 2005
Karma: 4
Senior Member
Matt Colie wrote on Wed, 14 September 2016 19:08
Tim,

In spite of what has been posted, do not be surprised if you can not get at it. It may be different in later BFs, but in my 73 - 23 it can not be done. I also have a real struggle to get the cover off the control board.

I suggest that you get the older manual that covers the BF (4.0) X7425. It can be downloaded. Removal of a BF is different than a NH(6.0) and if you try to do it that way, you will end up in a bind.

You do not need to fully disconnect the unit, just the supporting mounts need be set loose so you can pull the BF clear of the coach and make access to the bridge simple.

Matt


Apparently there were lots of variations in the way the older coaches were configured. As I recall we had no difficultly accessing the rectifier when I helped diagnose a no AC output problem with my former neighbors '73 23' Canyon Lands. As it turned out someone else had replaced the rectifier. Here is a photo of his bridge rectifier. The plastic socket had been discarded.

http://www.palmbeachgmc.com/images/onan0167.jpg

http://www.palmbeachgmc.com/images/onan0167.jpg




Richard
76 Palm Beach
SE Michigan
www.PalmBeachGMC.com

Roller Cam 455, TBI+EBL, 3.42 FD, 4 Bag, Macerator, Lenzi (brakes, vacuum system, front end stuff), Manny Tranny, vacuum step, Tankless + OEM water heaters.
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