Low voltage fuse box melt down

[Jim Shunkwiler]

Joel do you think water in the battery compartment could've caused my problem?

[Joel Ashley]

I wouldn't think water in your battery compartment to have caused this specific issue.  Is the green lamp still on at the bottom left of the Multiplex Control Master?  Or is it red for "Fault".

I'm no electrician but I'd consider pinching the sides of the 2 white connectors on the Multiplex Control Master and removing them.  I would expect this to turn off your switch backlights that are stuck on, and may protect anything in the Multiplex system yet in jeopardy.  Taking the cover off the black inset House Fuse Box and pulling the fuse to the Multiplex Control Master is also an option;  I think that is fuse number 9, Multiplex CPU.

Of course if you haven't already lost some or all of your 12 volt lighting from either or both A and B dimmer modules, this will disable them.  The fans may still be operative via their on-board switches, I'm not sure, but unfortunately the water pump likely won't come on if Module B is out of commission.

As Ed suggested, a call to BCS in Bend may glean experienced input regarding Multiplex and maybe insight into the overheated J2 connector with no blown fuses.

Be sure to print copies of the diagrams for your service tech.  When the cause is determined next week, please advise us.

Joel

[Jim Shunkwiler]

My multiplex control is completely burned and melted. I could email you pictures but I've been unable to post them from my iPad. So the fact that my backlights are on and there is no control unit hooked up tell you anything.

[Joel Ashley]

I thought the damage was just to the connector and board at module A.  The CPU master control (IPX on the diagram) is fried too?

The schematic and CPU box markings indicate the red/white stripe wire from the 3-wire white connector supplies power to the switch backlights.  Disconnecting it and/or yanking the CPU fuse should shut down the backlights.

Joel

[Jim Shunkwiler]

The upper left  corner of the controller module A with a 2 wire connector was burned the most. It appears those two wires caused module A to melt then burn. It's just  module A that's toast.

[Edward Buker]

Jim,

That multiplex controller contains a lot of electrical components and by design it should have probably had better protection for some circuitry breakdown that has occurred. Evidently it was not adequately engineered to be fuse protected for the internal short that was created. Water in the battery compartment (we are not talking under water here) should be of no issue. You have not had a low voltage situation that has affected multiple electronics in the coach and no alarms for your charging system I assume from what you have said.

I would try and read who the manufacturer is from the good board. If they are in business I would call them and tell them you have had a board burn up that luckily did not result in a fire. I would ask if they have seen the problem, and if there is a redesign? Say that you would like to find a source for a new unit and do they have a recommended source with the redesigned parts. If there is no redesign then ask if they would like your board for failure analysis given it could have burned down your coach. Monaco or BCS may have parts but you may learn more if the manufacturer is available and willing to work with you. It is not unheard of for a concerned manufacturer to provide you with a new one to get yours back if a possible fire was involved.

I did not see how badly this unit burned and if you feel there was a real danger of fire, it sounds like maybe it was. One option to consider is getting an aluminum box bent up that would contain these Multiplex units with some kind of open metal grill cover for heat dissipation and a cut out for the wire plug entries. From what I can tell in Joel's photos that would be an option to provide better protection from fire. That is sometimes done with electrical components that handle power and produce heat like these units. This does not have to be done as part of this repair and getting the lighting back on line, just something to consider a bit later for piece of mind.

I would also ask if anyone else on the forum has had a multiplex unit "smoke" to please let us know. If this is a completely isolated incident then you may feel better about it, if this has happened before then I would be wary, even once is too much when it comes to a possible fire.

Later Ed

[Edward Buker]

Jim,

I just read your latest post and it may have been a loose plug in connector creating the heat. Again only you can see the burn origin and result. If it was a connector then I would replace that along with the board.

Later Ed

[Jim Shunkwiler]

Ok thank you sir for your help.

[Joel Ashley]

I just tried posting a photo here off my iPad and it worked fine, Jim.  In fact it was easier than using my PC.  The only problem is images taken with the iPad itself, especially from poorly lit subjects, are not very highly resolved.

The reason you may not successfully post here is that it won't work if there isn't already some text in the message field.  Many people don't realize that.  Plus, you must use the "More Post Options" in Quick Reply, or you can't add pix.  Otherwise just use the field associated with the "newreply" button.  

 Add text in the message field, then click Choose File, then either "Choose Existing" or "Take Photo or Video".

From "Choose Existing" click the album and then the photo you want to post, then click "Attach (and add more)".

Or from "Take Photo or Video" take an iPad photo and hit "use" at the bottom;  then click "Attach (and add more)".

The iPad-taken photos probably have low enough resolution as to not exceed the 1MB size limit for posting here.  Other camera produced images need to be resized smaller as per Steve's post here, or the system won't accept them.  The simplest way I use regularly, on a PC anyway, is to open a photo in the Paint program.  Choose the "Image" menu tab and then "Stretch/Skew", change both size parameters from 100 down to about 25-30 percent, then save the result.  That image should be sized well within the website's guidelines.

Joel

[Jim Shunkwiler]

My choose file Doesn't allow me to select it even with txt in Message area. I'll have to figure something else out. Must be my iPad 1.

[Glenn Perkins]

Thanks so much for the help. Another interesting result after the incident is all the light switches are lit up and stay on.I wish I was near Bend but  I'm in Houston and will be taking coach to  local shop Monday. Do you think water in the  the battery compartment could've caused this problem.

Hopefully no to the RV Shack in Livingston!  If so, be careful, very careful ... see my cooling unit posting of earlier today for details ... as these folks IMHO are competant to work on travel trailers (maybe) but NOT high end coaches.