Follow Up On RV What Happens When...

Steve@Advance

Well-known Member
Posted about a week ago about the RV that got
connected to 220v...

Got the new 12v converter Friday, installed it
today. I went with the $106 Power Max. Modified
the case to mount it in place of the more
expensive Paralax replacement part.

Apparently there was no further damage to
anything 12v powered.

The refrigerator appears to be working, at least
the "auto" light was on, couldn't tell if it was
getting cold, it was already cold from the
weather.

The water heater was drawing amps, so it was
working. It would have fired on LP if there were
any, at least it went through the ignition
procedure.

AC seems OK, but so cold I couldn't tell if it
was cooling.

The water pump worked and tank level indicators
were saying something, assume they were right.

Looks like the only other casualty was the
microwave. I didn't find a fuse, but there was
power to the control board and the LED was blank,
so afraid it's dead. The owner said she'd find
another one, not to worry about it.

Thanks for the help and the offers, they're ready
to move in now. Mom will be glad to get them out
of her house... Again!
 


Grandma used to say......
Company is like fish... After three days, they both start to stink..

Mom said... Glad to see them come. Really glad to see them go!.
 
Before you give up on the microwave, try this simple test. Verify that the 120 Volt receptacle its plugged into actually has power. Plug the microwave in. WAIT at least 5 minutes. See if the display now comes back to life.

My hunting buddy's camper suffered a short in the main distribution box. After we troubleshot the problem and repaired it, we went through all the appliances and the specialty RV microwave appeared to be dead just as you described in your post. No display, no response to controls, seemingly a write-off.

I told him to leave it plugged in while we had lunch. Lo-and-behold, the display came back to life, the controls worked, food would cook, and it has worked fine ever since.

We conjectured that the microcontroller inside it has some sort of protective feature in it that keeps it shut down for a period of time after a total power loss.
 
Steve,


Microwaves have a fuse inside the cabinet near the main power entrance . They are the old glass auto types , but especially made for microwaves and are called ceramic fuses .Size ( amps ) of fuses depends on the size ( power ) of the microwave . Open the cabinet up and locate where the power supply ( 120vac , assuming that it's a 120 vac ) . It should be located in the vicinity where the power comes in . Useally , you will need a Phillips screwdriver ( medium size ) as well as a set of security bits and a driver for them . Always let the high voltage capictors discharge before opening the case !!!

Whizkid
a178471.jpg
 
(quoted from post at 04:01:26 01/06/15) Steve,


Microwaves have a fuse inside the cabinet near the main power entrance . They are the old glass auto types , but especially made for microwaves and are called ceramic fuses .Size ( amps ) of fuses depends on the size ( power ) of the microwave . Open the cabinet up and locate where the power supply ( 120vac , assuming that it's a 120 vac ) . It should be located in the vicinity where the power comes in . Useally , you will need a Phillips screwdriver ( medium size ) as well as a set of security bits and a driver for them . Always let the high voltage capictors discharge before opening the case !!!

Whizkid
a178471.jpg

Whizkid
Just thinking about what may have melted in the microwave.
Being that he had a 120 volt microwave that was subjected to 240 volt I don't see how a condition to blow a fuse was created.
Doubling the voltage should have cut the amp draw in half.
A piece of fuse wire does not care what the voltage is as long as the amps going through are below it's rating.
If 240 volt went through the transformer and if it's insulation was good the voltage would have come out at twice what it was supposed to be then the fun and welding starts.
 
Determined ,

Yes something could have melted , but depending on the maximum rating for the fuse it could have shot it . Think about it - what happens when you send to much power into something ? Something will be overloaded , fried , shot or something and the best that you can home for is the fuse shot and you got lucky !!!! If something is rated 12 volts and you send 24 volts into it for example or 220 into a 120 device . While, I'll agree that most fuses are rated 120 / 240 there are some that are voltage rated as well as amps !!
It was worth a shot to check it anyways !!!!


Whizkid
 
Doubling the voltage cuts the amp in half for the same power, but if you double the voltage and don't double the resistance the amperage will also double.
 

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