Big 12v Fuse in 78 Royale House fuse panel

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Totality

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We were camping last weekend and all of a sudden there was a pop, all 12v (other than the fridge) went out and there was a smell of burning.
on investigation the buzz box was very hot and the big fuse in the 12v panel had blown.

I've ordered a new PD 9245C (iirc) power convertor which should arrive tomorrow.

however I forgot to pull the blown fuse so I could get replacement...and coach is not very close by...so question is what is the correct type and
rating for this fuse?

hopefully the buzz box didnt toast my house batteries, fingers crossed.

thanks in advance

Pete
--
Cary, NC

1978 Center Kitchen Royale.
 
You better check that house battery, Pete. That's what toasted my buzz box a few years ago. Had to replace both battery and converter.
--
Terry Kelpien

ASE Master Technician

73 Glacier 260

Smithfield, Va.
 
First of all. Keep all the pieces before they go to the dumpster. Just replacing one piece in a system of pieces without doing the troubleshooting is just throwing money away.

I would suggest that replacing the original buzzbox with newer technology is a good insurance policy to extend the life of the coach batteries. So do that anyway.

Fuses are sized to protect the wire from melting.

You need to spend a little bit of time to determine what was happening at the time the fuse blew.

Sit down somewhere very quiet, nice fresh cup of coffee, pencil, and a nice clean sheet of quad paper.
Write down as much information that you can recall as to what was running just before the failure. Ask others as well. The less technical the person, the more likely they will have the 'critical' question.

Make a list of what the fuse protected. Then go digging into circuit, and keep digging until you find something that could cause the failure. If you don't find it the first time, you will have the same event again.
A common 'fix' is to substitute a larger fuse. Don't do it! If you do, the wire is no longer protected and it is possible the wire can heat up, melting insulation and worse.

>
>
> We were camping last weekend and all of a sudden there was a pop, all 12v (other than the fridge) went out and there was a smell of burning.
> on investigation the buzz box was very hot and the big fuse in the 12v panel had blown.
>
> I've ordered a new PD 9245C (iirc) power convertor which should arrive tomorrow.
>
> however I forgot to pull the blown fuse so I could get replacement...and coach is not very close by...so question is what is the correct type and
> rating for this fuse?
>
> hopefully the buzz box didnt toast my house batteries, fingers crossed.
>
>
> thanks in advance
>
>
> Pete
> --
> Cary, NC
>
> 1978 Center Kitchen Royale.
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
I only had inside 12v lighting on, the fridge was on AC (so only the electronics taking 12v) and possibly the gas water heater (again low current for
the electronics in it)

I suspect the Buzz box primarily and /or the house batteries as buzz box was HOT.

Is the connection from buzz box to the house batteries through that fuse? Seems like it should be.(rats, all my manuals are in the coach too).

I have two 12v house batteries in parallel.
--
Cary, NC

1978 Center Kitchen Royale.
 
Pete
We're out camping now. If you need, I can take a couple of pictures of my breaker panel and send them to you if that helps. Only problem would be
pulling out the supplies to get to the panel(our rear lounge was converted to a permanent bed, so it's all storage under the bed).
Call me if I can help
Scott 858-212-8760
--
Scott Nutter
1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21 final drive, Quad bags, tankless water heater, everything Lenzi. Alex Ferrera
installed MSD Atomic EFI
Houston, Texas
 
It is possible that the big fuse if for the buzzbox to battery connection. If the batteries were low on water they will take a lot of current from the buzzbox. Look further. Take your time.

>
>
> I only had inside 12v lighting on, the fridge was on AC (so only the electronics taking 12v) and possibly the gas water heater (again low current for
> the electronics in it)
>
> I suspect the Buzz box primarily and /or the house batteries as buzz box was HOT.
>
> Is the connection from buzz box to the house batteries through that fuse? Seems like it should be.(rats, all my manuals are in the coach too).
>
> I have two 12v house batteries in parallel.
> --
> Cary, NC
>
> 1978 Center Kitchen Royale.
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
> Pete
> We're out camping now. If you need, I can take a couple of pictures of my breaker panel and send them to you if that helps. Only problem would be
> pulling out the supplies to get to the panel(our rear lounge was converted to a permanent bed, so it's all storage under the bed).
> Call me if I can help
> Scott 858-212-8760

Thanks, I really just need to know fuse type and rating. I'm an engineer and can work out the problems safely.

Pete.

--
Cary, NC

1978 Center Kitchen Royale.
 
Hey guys,

I have two things to add here and either may be significant.

First:
The buzzboxes that I still use as DC bench supplies both run kind of warm even when unloaded.
So don't use box temperature as a diagnostic there.

Second:
If you have two 12 jars in parallel, Watch Out!!
When I still did a lot of boat work, I used to like paralleled 12V banks as they provided a regular income. When one jar stumbles, the other can
provide the needed power to make it explode. I still have the canned letter to insurance companies about how it was not as bad as expected, we saved
the boat.....
The typical bill for the cleanup was three hours. That does not include repairs and new jars.

I also still have the baking soda shaker in the coach that says,
For Acid Spills and Emergency Baking."
Mary doesn't see the humor....

Matt - on the way to Erie PA for the night and Rochester NY tomorrow (no Walmart ONP there)
--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit
 
Matt, thanks for the comments.

The buzz box was HOT, as in too hot to touch, way beyond whats good for electronics (or being in a tinderbox RV)....even 70s electronics. yes it
might still work and may not have directly been the cause..... but its coming out anyway and getting replaced with smarter modern one.

And I'm going to go down to a single 12v House battery for now. We don't really boon dock, and have good Onan genny in any case.

when I retire in a couple more years and start touring seriously, I'll get the two 6v batteries (in series) recommended, but for now, one 12v will be
fine.

Pete

> Hey guys,
>
> I have two things to add here and either may be significant.
>
> First:
> The buzzboxes that I still use as DC bench supplies both run kind of warm even when unloaded.
> So don't use box temperature as a diagnostic there.
>
> Second:
> If you have two 12 jars in parallel, Watch Out!!
> When I still did a lot of boat work, I used to like paralleled 12V banks as they provided a regular income. When one jar stumbles, the other can
> provide the needed power to make it explode. I still have the canned letter to insurance companies about how it was not as bad as expected, we
> saved the boat.....
> The typical bill for the cleanup was three hours. That does not include repairs and new jars.
>
> I also still have the baking soda shaker in the coach that says,
> For Acid Spills and Emergency Baking."
> Mary doesn't see the humor....
>
> Matt - on the way to Erie PA for the night and Rochester NY tomorrow (no Walmart ONP there)

--
Cary, NC

1978 Center Kitchen Royale.
 
Got out to the coach after work. Fuse is 50A a little longer longer and twice the diameter of the normal glass fuses. I found replacement easily
in local autozone.

The new converter has arrived too...
--
Cary, NC

1978 Center Kitchen Royale.
 
If you had a 50A fuse fail, there is something VERY serious in the electrical system. Do NOT replace the fuse and hope for the best. You are looking for something major. A shorted coach battery comes to mind. Until you fing the problem, do not leave that fuse in the circuit when you are not at the coach.

>
>
> Got out to the coach after work. Fuse is 50A a little longer longer and twice the diameter of the normal glass fuses. I found replacement easily
> in local autozone.
>
> The new converter has arrived too...
> --
> Cary, NC
>
> 1978 Center Kitchen Royale.
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
Rich, yes I suspect the house batteries too.........im taking both out and checking them first.....And only putting one, possibly new, one back.
I'll also check with meter to see if there is a short between the fused side and earth.

Pete
--
Cary, NC

1978 Center Kitchen Royale.
 
Pete,
I'm my 78 center kitchen I don't have any 50 amp glass fuses by the breaker box. Is yours in the aft area of your coach? All I can see is a breaker
box on mine. It all appears to be original. I don't think the previous owners changed out anything original. Being that the Royals were upfitted by
coachman they are not all the same?
Scott.
--
Scott Nutter
1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21 final drive, Quad bags, tankless water heater, everything Lenzi. Alex Ferrera
installed MSD Atomic EFI
Houston, Texas
 
Something that causes a 50A fuse to blow is big. 50A capacity wire is #6 or larger. The auto parts store can be a big help with testing the bits and pieces. Please let me know what the results are.

>
>
> Rich, yes I suspect the house batteries too.........im taking both out and checking them first.....And only putting one, possibly new, one back.
> I'll also check with meter to see if there is a short between the fused side and earth.
>
>
> Pete
> --
> Cary, NC
>
> 1978 Center Kitchen Royale.
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
The AC breakers, 12v fuses and buzz box are all in a box right at the very back of the coach between the two rear bench seats. There is one 50A glass
fuse and 6 or so smaller fuses alien one panel. Looks original but who knows.

Pete

> Pete,
> I'm my 78 center kitchen I don't have any 50 amp glass fuses by the breaker box. Is yours in the aft area of your coach? All I can see is a
> breaker box on mine. It all appears to be original. I don't think the previous owners changed out anything original. Being that the Royals were
> upfitted by coachman they are not all the same?
> Scott.

--
Cary, NC

1978 Center Kitchen Royale.
 
The AC breakers, 12v fuses and buzz box are all in a box right at the very back of the coach between the two rear bench seats. There is one 50A glass
fuse and 6 or so smaller fuses alien one panel. Looks original but who knows.

Pete

> Pete,
> I'm my 78 center kitchen I don't have any 50 amp glass fuses by the breaker box. Is yours in the aft area of your coach? All I can see is a
> breaker box on mine. It all appears to be original. I don't think the previous owners changed out anything original. Being that the Royals were
> upfitted by coachman they are not all the same?
> Scott.

--
Cary, NC

1978 Center Kitchen Royale.
 
Sounds like a low impedance house battery. Just one of the several different fail modes batteries experience, especially as they age out.
--
John Lebetski
Woodstock, IL
77 Eleganza II
 
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