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[GMCnet] Aux Battery Doesn't charge when plugged in [message #121079] Wed, 06 April 2011 13:25 Go to next message
Peter Brodeski is currently offline  Peter Brodeski   United States
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Registered: March 2011
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Hello, I've noticed that my aux battery doesn't charge when I plug into the 120.  I thought maybe it was a bad battery so I just got a brand new one and I'm still having the same problem.  The only way to charge my battery is to start the engine and let it run for a while or run the generator for awhile, which is kind of annoying when you're camping for a few nights. I'm still a newbie to my GMC and not sure where to start to figure out how to fix this without going to a mechanic. Any help would be appreciated!

Thanks,

Pete Brodeski
1976 Palm Beach
Rockford, IL
 
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Re: [GMCnet] Aux Battery Doesn't charge when plugged in [message #121088 is a reply to message #121079] Wed, 06 April 2011 14:39 Go to previous messageGo to next message
idrob is currently offline  idrob   United States
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Registered: January 2005
Location: Central Idaho
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Peter Brodeski wrote on Wed, 06 April 2011 11:25

Hello, I've noticed that my aux battery doesn't charge when I plug into the 120.  I thought maybe it was a bad battery so I just got a brand new one and I'm still having the same problem.  The only way to charge my battery is to start the engine and let it run for a while or run the generator for awhile, which is kind of annoying when you're camping for a few nights. I'm still a newbie to my GMC and not sure where to start to figure out how to fix this without going to a mechanic. Any help would be appreciated!

Thanks,

Pete Brodeski
1976 Palm Beach
Rockford, IL
 




Sounds like something is wrong with your converter/charger. If it is the original (which we fondly call the Buzz Box) because of the sound it makes, it might have just been turned off or unplugged by the PO (previous owner), Check in the cabinet where the circuit breaker box is for a gray box, about 6"x6" x 12" and with the power on, listen. If it is humming, at least you have power to it. If not, look for the power plug and make sure that it is plugged in and that the circuit is live.

Report back to us on that much. We can go from there. This is only a starting place if you are not very familiar with the GMC.


Rob Allen
former owner of '76 x-PB
Re: [GMCnet] Aux Battery Doesn't charge when plugged in [message #121090 is a reply to message #121079] Wed, 06 April 2011 14:47 Go to previous messageGo to next message
Bob de Kruyff   United States
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
Senior Member
Peter Brodeski wrote on Wed, 06 April 2011 12:25

Hello, I've noticed that my aux battery doesn't charge when I plug into the 120.  I thought maybe it was a bad battery so I just got a brand new one and I'm still having the same problem.  The only way to charge my battery is to start the engine and let it run for a while or run the generator for awhile, which is kind of annoying when you're camping for a few nights. I'm still a newbie to my GMC and not sure where to start to figure out how to fix this without going to a mechanic. Any help would be appreciated!

Thanks,

Pete Brodeski
1976 Palm Beach
Rockford, IL
 
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What's confusing is that the battery charges while running the Onan--normally the convertor wouldn't know the difference between shore power or the Onan.


Bob de Kruyff
78 Eleganza
Chandler, AZ
Re: [GMCnet] Aux Battery Doesn't charge when plugged in [message #121091 is a reply to message #121088] Wed, 06 April 2011 14:42 Go to previous messageGo to next message
Ray Erspamer is currently offline  Ray Erspamer   United States
Messages: 1707
Registered: May 2007
Location: Milwaukee Wisconsin
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Senior Member
But he said it charges when the generator is on, the generator just supplies
110v power to the converter just like the land line chord does.....or am I
missing something ???

Ray


Ray & Lisa Erspamer
78 Royale Center Kitchen
TZE368V101144
Wauwatosa, Wisconsin 53226
Email: 78GMC-Royale@att.net
414-745-3188
Web Site: http://ray-lisa.page.tl/




________________________________
From: Rob Allen <profmail@wildblue.net>
To: gmclist@temp.gmcnet.org
Sent: Wed, April 6, 2011 2:39:50 PM
Subject: Re: [GMCnet] Aux Battery Doesn't charge when plugged in



Peter Brodeski wrote on Wed, 06 April 2011 11:25
> Hello, I've noticed that my aux battery doesn't charge when I plug into the
>120. I thought maybe it was a bad battery so I just got a brand new one and I'm
>still having the same problem. The only way to charge my battery is to start
>the engine and let it run for a while or run the generator for awhile, which is
>kind of annoying when you're camping for a few nights. I'm still a newbie to my
>GMC and not sure where to start to figure out how to fix this without going to a
>mechanic. Any help would be appreciated!
>
> Thanks,
>
> Pete Brodeski
> 1976 Palm Beach
> Rockford, IL
>


Sounds like something is wrong with your converter/charger. If it is the
original (which we fondly call the Buzz Box) because of the sound it makes, it
might have just been turned off or unplugged by the PO (previous owner), Check
in the cabinet where the circuit breaker box is for a gray box, about 6"x6" x
12" and with the power on, listen. If it is humming, at least you have power to
it. If not, look for the power plug and make sure that it is plugged in and
that the circuit is live.

Report back to us on that much. We can go from there. This is only a starting
place if you are not very familiar with the GMC.
--
Rob Allen
former owner of '76 x-PB
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Ray Erspamer 78 GMC Royale Center Kitchen 403, 3.70 Final Drive Holley Sniper Quadrajet EFI System, Holley Hyperspark Ignition System 414-484-9431
Re: [GMCnet] Aux Battery Doesn't charge when plugged in [message #121096 is a reply to message #121090] Wed, 06 April 2011 15:10 Go to previous messageGo to next message
Mr ERFisher is currently offline  Mr ERFisher   United States
Messages: 7117
Registered: August 2005
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Senior Member
sounds like the says only charges from the gmc engine

gene'


On Wed, Apr 6, 2011 at 12:47 PM, Bob de Kruyff <NEXT2POOL@aol.com> wrote:

>
>
> Peter Brodeski wrote on Wed, 06 April 2011 12:25
> > Hello, I've noticed that my aux battery doesn't charge when I plug into
> the 120. I thought maybe it was a bad battery so I just got a brand new one
> and I'm still having the same problem. The only way to charge my battery is
> to start the engine and let it run for a while or run the generator for
> awhile, which is kind of annoying when you're camping for a few nights. I'm
> still a newbie to my GMC and not sure where to start to figure out how to
> fix this without going to a mechanic. Any help would be appreciated!
> >
> > Thanks,
> >
> > Pete Brodeski
> > 1976 Palm Beach
> > Rockford, IL
> >
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
> What's confusing is that the battery charges while running the
> Onan--normally the convertor wouldn't know the difference between shore
> power or the Onan.
> --
> Bob de Kruyff
> 78 Eleganza
> Chandler, AZ
> _______________________________________________
> 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] Aux Battery Doesn't charge when plugged in [message #121112 is a reply to message #121079] Wed, 06 April 2011 17:20 Go to previous messageGo to next message
RF_Burns is currently offline  RF_Burns   Canada
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Location: S. Ontario, Canada
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Senior Member
From my reading, it will charge while on the Onan. I wonder if the PO had connected the battery charger (alternator) built into the Onan to charge the battery after the converter failed?

Do the 12v house lights brighten when the 120V is plugged in? Or disconnect one terminal of the house battery and see if you have any house lights when plugged into 120Vac, if not then the converter if faulty.


Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
Re: [GMCnet] Aux Battery Doesn't charge when plugged in [message #121113 is a reply to message #121079] Wed, 06 April 2011 17:36 Go to previous messageGo to next message
LARRY L CALHOUN is currently offline  LARRY L CALHOUN   United States
Messages: 33
Registered: March 2004
Location: COEUR D ALENE ID.
Karma: 0
Member
Pete, a 76 should not have one but check and see if there is a transfur switch on your curcit breaker box.

Larry Calhoun GMC Cascader 76 Glenbrook COEUR D ALENE ID.
Re: [GMCnet] Aux Battery Doesn't charge when plugged in [message #121128 is a reply to message #121079] Wed, 06 April 2011 19:12 Go to previous messageGo to next message
roy1 is currently offline  roy1   United States
Messages: 2126
Registered: July 2004
Location: Minden nevada
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Senior Member
If it isn't a simple fix like a tripped circuit breaker or plug not plugged in. This would be a good excuse to replace the old buzz box with a nice smart converter. The onan does have a small battery charger in it that most folks disconnect this only puts out a few amps charge and possibly what is charging when the generator is running.
Roy


Roy Keen Minden,NV 76 X Glenbrook
Re: [GMCnet] Aux Battery Doesn't charge when plugged in [message #121142 is a reply to message #121112] Wed, 06 April 2011 20:08 Go to previous messageGo to next message
emerystora is currently offline  emerystora   United States
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Registered: January 2004
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Senior Member

On Apr 6, 2011, at 4:20 PM, Bruce Hislop wrote:

>
>
> From my reading, it will charge while on the Onan. I wonder if the PO had connected the battery charger (alternator) built into the Onan to charge the battery after the converter failed?
>
> Do the 12v house lights brighten when the 120V is plugged in? Or disconnect one terminal of the house battery and see if you have any house lights when plugged into 120Vac, if not then the converter if faulty.
> --
> Bruce Hislop,
> S
Bruce
Probably not the prior owner. The Onan battery charger would charge the battery even when the original converter was hooked up. In the case of my 1977 when I changed out the originlal buzz box and put on a Statpower Xantrex Tru Charge I had to unhook the changer on the Onan because the Statpower detected it and would not put out any charge if there was another charging source. So, I know that both were hooked up originally.

Emery Stora
77 Kingsley
Santa Fe, NM


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Re: [GMCnet] Aux Battery Doesn't charge when plugged in [message #121157 is a reply to message #121096] Wed, 06 April 2011 21:54 Go to previous messageGo to next message
Bob de Kruyff   United States
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
Senior Member
Mr ERFisher wrote on Wed, 06 April 2011 14:10

sounds like the says only charges from the gmc engine

gene'


On Wed, Apr 6, 2011 at 12:47 PM, Bob de Kruyff <NEXT2POOL@aol.com> wrote:

>
>
> Peter Brodeski wrote on Wed, 06 April 2011 12:25
> > Hello, I've noticed that my aux battery doesn't charge when I plug into
> the 120. I thought maybe it was a bad battery so I just got a brand new one
> and I'm still having the same problem. The only way to charge my battery is
> to start the engine and let it run for a while or run the generator for
> awhile, which is kind of annoying when you're camping for a few nights. I'm
> still a newbie to my GMC and not sure where to start to figure out how to
> fix this without going to a mechanic. Any help would be appreciated!
> >
> > Thanks,
> >
> > Pete Brodeski
> > 1976 Palm Beach
> > Rockford, IL
> >
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
> What's confusing is that the battery charges while running the
> Onan--normally the convertor wouldn't know the difference between shore
> power or the Onan.
> --
> Bob de Kruyff
> 78 Eleganza
> Chandler, AZ
> _______________________________________________
> 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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Certainly not the way I read it.
sent from my cricket in the toilet at work


Bob de Kruyff
78 Eleganza
Chandler, AZ
Re: [GMCnet] Aux Battery Doesn't charge when plugged in [message #121182 is a reply to message #121079] Thu, 07 April 2011 07:40 Go to previous messageGo to next message
Richard Denney is currently offline  Richard Denney   United States
Messages: 920
Registered: April 2010
Karma: 9
Senior Member
On Wed, Apr 6, 2011 at 2:25 PM, pbrodeski <pbrodeski@me.com> wrote:

> Hello, I've noticed that my aux battery doesn't charge when I plug into the
> 120. I thought maybe it was a bad battery so I just got a brand new one and
> I'm still having the same problem. The only way to charge my battery is to
> start the engine and let it run for a while or run the generator for awhile,
> which is kind of annoying when you're camping for a few nights. I'm still a
> newbie to my GMC and not sure where to start to figure out how to fix this
> without going to a mechanic. Any help would be appreciated!
>

I'll write this for people reading this in the toilet at work:

"The only way to charge my battery is to

1. Start the engine and let it run for a while, or

2. Run the generator for a while."

The generators included a small 12-volt power supply that was used to charge
a separate generator starting battery. Your '76 is late enough not to have
the separate generator starting battery, but it might still have that
on-board battery charger.

Thus, it sounds to me as though the converter is dead or not putting out
full voltage.

If you don't have a digital voltmeter, go buy one. It is worth what it costs
for any RV owner. Measure the voltage at the battery terminals in three
conditions: With the 455 running, with the Onan running, and when plugged
into shore power (turn on some house lights and let it sit for a half hour
or so under shore power--that will bleed off any surface charge on the
battery). My bet is that you'll see something in the 14-volt range in the
first case, 13.something volts in the second case, and 12.6 volts in the
third case.

Then, disconnect the house battery. Plug the coach back into shore power.
Measure the voltage on the output bus of the converter. If the converter is
working, it should read 13.6 or 13.8 volts. If it reads zero (likely) or
under 13 volts, it needs to be replaced. If it reads 13.6 volts, reattach
the battery and measure it again. If it still reads 13.6 volts, but less
than that at the battery, then you have a problem with the battery charging
wire from the converter output to the house battery and you'll need to trace
that wire to find the problem. Start with the connections, of course.
Battery terminals for the house battery get even dirtier than on the engine
battery.

Part of the problem is that this aspect of coaches is first in line for
owner modifications, and it's hard to know how things are really wired. When
I bought my coach, the house and engine batteries were hard-wired in
parallel through an improperly wired Perko switch. I had to strip all that
out and start over.

This will give you a procedure to follow, and if you get stuck, more precise
data when you come back to the group for more help.

Rick "who recommends Progressive Dynamic Intellipower converter/chargers if
your buzzbox is bad (or even if it isn't)" Denney

--
'73 230 "Jaws"
Northern Virginia
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Re: [GMCnet] Aux Battery Doesn't charge when plugged in [message #121184 is a reply to message #121079] Thu, 07 April 2011 08:19 Go to previous messageGo to next message
John Ruff is currently offline  John Ruff   United States
Messages: 213
Registered: July 2007
Location: Chandler, AZ
Karma: 0
Senior Member

Try plugging something (a lightbulb) into the same outlet that the battery charger is plugged in to and see if it lights up when the motorhome is plugged into shore power.

That will tell you if the charger is getting voltage in shore power mode.

If the outlet gets power then it could be that the charger is either dead or not connected to your battery bank.

John

Peter Brodeski wrote on Wed, 06 April 2011 11:25

Hello, I've noticed that my aux battery doesn't charge when I plug into the 120.  I thought maybe it was a bad battery so I just got a brand new one and I'm still having the same problem.  The only way to charge my battery is to start the engine and let it run for a while or run the generator for awhile, which is kind of annoying when you're camping for a few nights.




John Ruff
Chandler, AZ
1975 Eleganza
WA3RIG

If I use ZDDP in a new car - will the tappets go flat?
Re: [GMCnet] Aux Battery Doesn't charge when plugged in [message #121188 is a reply to message #121079] Thu, 07 April 2011 10:13 Go to previous messageGo to next message
Peter Brodeski is currently offline  Peter Brodeski   United States
Messages: 8
Registered: March 2011
Karma: 0
Junior Member

On Apr 6, 2011, at 2:42 PM, gmclist-request@temp.gmcnet.org wrote:

> Peter Brodeski wrote on Wed, 06 April 2011 11:25
>> Hello, I've noticed that my aux battery doesn't charge when I plug into the 120. ?I thought maybe it was a bad battery so I just got a brand new one and I'm still having the same problem. ?The only way to charge my battery is to start the engine and let it run for a while or run the generator for awhile, which is kind of annoying when you're camping for a few nights. I'm still a newbie to my GMC and not sure where to start to figure out how to fix this without going to a mechanic. Any help would be appreciated!
>>
>> Thanks,
>>
>> Pete Brodeski
>> 1976 Palm Beach
>> Rockford, IL
>> ?
>
>
> Sounds like something is wrong with your converter/charger. If it is the original (which we fondly call the Buzz Box) because of the sound it makes, it might have just been turned off or unplugged by the PO (previous owner), Check in the cabinet where the circuit breaker box is for a gray box, about 6"x6" x 12" and with the power on, listen. If it is humming, at least you have power to it. If not, look for the power plug and make sure that it is plugged in and that the circuit is live.
>
> Report back to us on that much. We can go from there. This is only a starting place if you are not very familiar with the GMC.
> --
> Rob Allen
> former owner of '76 x-PB

Rob, I plugged in to 120 and checked the "buzz box" it was humming so I think there's power going to it. All my fuses on the fuse panel right next to it look ok. The only plug that I see in the cabinet was plugged in. It was right next to the water heater switch that was turned off (water heater doesn't work). All my plugs inside the cabin work when plugged in the 120 but my 12V cabin lights slowly dimmed out to nothing as I was working on it last night. I have a feeling that it's either a a back breaker or the "Buzz Box" is bad.

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Re: [GMCnet] Aux Battery Doesn't charge when plugged in [message #121191 is a reply to message #121079] Thu, 07 April 2011 10:26 Go to previous messageGo to next message
Peter Brodeski is currently offline  Peter Brodeski   United States
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Registered: March 2011
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Junior Member
The lights do not brighten when it's plugged into 120, they slowly die out.

I think it might be a bad converter if it's not the 50amp breaker. Does anyone have any recommendations for a new replacement "buzz box"?

Also, I'd like to say that I'm a new GMC owner and this email list is awesome. There's no way I would have figured out 90% of the stuff I have already learned by following this list and reading up on all the resources available online for the GMC.

Pete Brodeski
1976 Palm Beach
Rockford, IL


On Apr 6, 2011, at 5:18 PM, gmclist-request@temp.gmcnet.org wrote:

>>
>> From my reading, it will charge while on the Onan. I wonder if the PO had connected the battery charger (alternator) built into the Onan to charge the battery after the converter failed?
>
> Do the 12v house lights brighten when the 120V is plugged in? Or disconnect one terminal of the house battery and see if you have any house lights when plugged into 120Vac, if not then the converter if faulty.
> --
> Bruce Hislop,

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Re: [GMCnet] Aux Battery Doesn't charge when plugged in [message #121192 is a reply to message #121188] Thu, 07 April 2011 10:42 Go to previous messageGo to next message
mike miller   United States
Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon
Karma: 0
Senior Member
Peter Brodeski wrote on Thu, 07 April 2011 08:13

...
> I'm still a newbie to my GMC and not sure where to
> start to figure out how to fix this without going to a
> mechanic. Any help would be appreciated!

<< snipped a bunch >>

I have a feeling that it's either a a back breaker or the "Buzz Box" is bad.


Peter,

I suspect you are correct that the buzz box is bad. Even if it isn't bad, it really should be replaced anyway. The tech is old and it is to easy to kill batteries with one. Even a "good" buzz box is a bad converter. (But it makes a good 12 volt power supply.)

While it might not help with your current problem, it would be good to find a local GMC'er to go over your coach with you. You shouldn't have problems getting someone, most GMC'ers love to look at and talk GMC's.... getting them to STOP is more of a problem! This will really cut down on the learning curve. (Read save you money!) Check the local clubs and the black list for someone close.


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
Re: [GMCnet] Aux Battery Doesn't charge when plugged in [message #121227 is a reply to message #121079] Thu, 07 April 2011 14:01 Go to previous messageGo to next message
Richard Brown is currently offline  Richard Brown   United States
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Registered: May 2009
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Senior Member
Sounds like the switching relay in the buzz box may be bad. It's buzzing, so at least the transformer is at least partially OK. Here's a link to an article I found on repairing it: http://www.hayseed.net/~jpk5lad/RV%20Information/MagnaTek%20Pwr%20Converter/rv%20power%20converter.html  Even if I get a new converter, I'll keep the old one as an ace-in-the-hole.
The new converters are great for charging, but if you can't afford one right now, maybe this will help. I bought a timer that I plugged mine into so that it only runs for 4 hours max for the time being. I plan on getting a new one, but there are too many more important repairs needed at this time, like making it where it will go farther than a couple of miles without quitting on me. I need to replace the mufflers & install the block-off plates in the intake first.
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Richard & Carol Brown 1974 Eleganza SE 1174 Hickory Hills Dr. Murchison, TX. 75778
Re: [GMCnet] Aux Battery Doesn't charge when plugged in [message #121233 is a reply to message #121227] Thu, 07 April 2011 15:14 Go to previous messageGo to next message
Mr ERFisher is currently offline  Mr ERFisher   United States
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Registered: August 2005
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Senior Member
Here are some reasons to replace the buzz box

http://www.gmcmhphotos.com/photos/showphoto.php?photo=17531&cat=4507
or
http://goo.gl/xhv7v

gene



On Thu, Apr 7, 2011 at 12:01 PM, Richard Brown
<wings77sporty@sbcglobal.net>wrote:

> Sounds like the switching relay in the buzz box may be bad. It's buzzing,
> so at least the transformer is at least partially OK. Here's a link to an
> article I found on repairing it:
> http://www.hayseed.net/~jpk5lad/RV%20Information/MagnaTek%20Pwr%20Converter/rv%20power%20converter.html<http://www.hayseed.net/%7Ejpk5lad/RV%20Information/MagnaTek%20Pwr%20Converter/rv%20power%20converter.html>
> Even if I get a new converter, I'll keep the old one as an ace-in-the-hole.
> The new converters are great for charging, but if you can't afford one
> right now, maybe this will help. I bought a timer that I plugged mine into
> so that it only runs for 4 hours max for the time being. I plan on getting a
> new one, but there are too many more important repairs needed at this time,
> like making it where it will go farther than a couple of miles without
> quitting on me. I need to replace the mufflers & install the block-off
> plates in the intake first.
> _______________________________________________
> 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] Aux Battery Doesn't charge when plugged in [message #121274 is a reply to message #121079] Thu, 07 April 2011 21:02 Go to previous messageGo to next message
Hardie Johnson is currently offline  Hardie Johnson   United States
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Peter Brodeski wrote on Wed, 06 April 2011 14:25

Hello, I've noticed that my aux battery doesn't charge when I plug into the 120.  I thought maybe it was a bad battery so I just got a brand new one and I'm still having the same problem.<>

I'm thinking the problem is with the isolator diode bridge - that funny blue finned thing under the hood that sort of links the house and chassis battery circuits. I am sure someone can tell you how to test it. Me, I just threw it away and replaced it with a Yandina combiner, to go with the new modern charger from Progressive Dynamics.
"See also: Rick Denny"


Hardie Johnson "Crashj"
1973 26 foot Glacier, White Thing
Raleigh NC
Re: [GMCnet] Aux Battery Doesn't charge when plugged in [message #121285 is a reply to message #121274] Thu, 07 April 2011 22:28 Go to previous messageGo to next message
Ken Burton is currently offline  Ken Burton   United States
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Hardie Johnson wrote on Thu, 07 April 2011 21:02

Peter Brodeski wrote on Wed, 06 April 2011 14:25

Hello, I've noticed that my aux battery doesn't charge when I plug into the 120.  I thought maybe it was a bad battery so I just got a brand new one and I'm still having the same problem.<>

I'm thinking the problem is with the isolator diode bridge - that funny blue finned thing under the hood that sort of links the house and chassis battery circuits. I am sure someone can tell you how to test it. Me, I just threw it away and replaced it with a Yandina combiner, to go with the new modern charger from Progressive Dynamics.
"See also: Rick Denny"


The isolator does not enter the picture and has nothing to do with charging the house battery(s) from the converter or with supplying power to the 12 volt house circuits when the vehicle is parked and running on 120 volts.


Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
Re: [GMCnet] Aux Battery Doesn't charge when plugged in [message #121290 is a reply to message #121188] Fri, 08 April 2011 00:09 Go to previous messageGo to previous message
idrob is currently offline  idrob   United States
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Peter Brodeski wrote on Thu, 07 April 2011 08:13



> Sounds like something is wrong with your converter/charger. If it is the original (which we fondly call the Buzz Box) because of the sound it makes, it might have just been turned off or unplugged by the PO (previous owner), Check in the cabinet where the circuit breaker box is for a gray box, about 6"x6" x 12" and with the power on, listen. If it is humming, at least you have power to it. If not, look for the power plug and make sure that it is plugged in and that the circuit is live.
>
> Report back to us on that much. We can go from there. This is only a starting place if you are not very familiar with the GMC.
> --
> Rob Allen
> former owner of '76 x-PB

Rob, I plugged in to 120 and checked the "buzz box" it was humming so I think there's power going to it. All my fuses on the fuse panel right next to it look ok. The only plug that I see in the cabinet was plugged in. It was right next to the water heater switch that was turned off (water heater doesn't work). All my plugs inside the cabin work when plugged in the 120 but my 12V cabin lights slowly dimmed out to nothing as I was working on it last night. I have a feeling that it's either a a back breaker or the "Buzz Box" is bad.




It does sound like you need a new converter/charger. Just be sure your current unit does have 120 volts going to it. Most suggested replacement would be a Progressive Dynamics PD 9245 with charge wizzard. I used a slightly different one when I did mine, but here is a photo shoot of my job.

http://www.gmcmhphotos.com/photos/showgallery.php?cat=3953


Rob Allen
former owner of '76 x-PB
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