Practical troubleshooting your RV, 101 #1

[GARY MINKER]

I am sure someone answered you already but you lost the neutral. thank goodness for surge arrestors or the damage would be much worse. This makes a case for inspecting your cordage and panels once a year. Gary --- On Sun, 12/28/08, Bob Lawrence wrote: From: Bob Lawrence Subject: [WanderlodgeForum] Re: Practical troubleshooting your RV, 101 #1 To: WanderlodgeForum@yahoogroups.com Date: Sunday, December 28, 2008, 7:39 PM Hi Ralph, On our trip here to South Padre Island, we stopped at a campground in Rockport. I was working outside with my Dremel plugged in and it bogged down. I heard a pop and I lost all the grounds in the bus and blew 6 surge protectors. Where do I look? Could the ground have melted off at the bus 50 amp inlet? Bob Lawrence 84 PT36 South Padre Island, Texas > Hello everyone; > > Electrical systems in any venue, to many, is confusing and it does not have > to be. With just a few simple rules, one can do a systems check no matter > if it is a 12vdc/24vdc or an 110vac system. > > The words, what? where?, how? and why? come to mind as the very basic start > to finding a problem with systematic troubleshooting. > > What? equates to, What is the real problem? (does not mean what the problem > appears to be.) > Where? equates to the physical location of items along a "path" in a given > system. > How? equates to how does it or is supposed to work? > Why? (remember when Dad used to say "there is no such word as why." The why > equates to why did it happen in the first place. > > It is important to try to learn how a system is designed to work or the > right way to say this is "know the sequence of operation." If you know how > it is supposed to work then you are ready to start trying to; "recognize" > "localize" and "isolate" a problem. > > Ok lets pick a simple system; 12vdc fan. Problem, fan does not run. Ok so > now we know it is a fan not coming on, so the problem is "recognized. " So > what do we really know about "where it is." A switch on a dash, the fan is > located behind a panel near the co pilots feet, but is there more in that > system besides a switch and fan motor? Could there be a "relay" in line > between the switch and fan? Could there be a circuit breaker or fuse, > between the switch and fan motor? All are valid questions and can be > answered with a "sequence" of operation. > > "Sequence" of operation for the system above; 1.it is a 12vdc system so > from the system circuit breaker, 12vdc is supplied to a switch and from the > switch to the coil of a 12vdc relay then 12vdc passes through the contacts > of the relay to the fan motor and the fan motor runs. > > Now we know the "how" it works, we can start to "localize" the problem. > Starting at the circuit break we are going to check for 12vdc to be sure > the switch is in fact getting power. Yes voltage is present. Then go to the > switch and check for 12vdc, yes voltage is present on one side, then switch > the switch to the run position and check for voltage. It is found that > 12vdc is present on the out put side of the switch. Next stop is the relay > coil, check for 12vdc at the coil of the relay, yes 12vdc is resent, then > check the out put side of the relay, no voltage found, hmmm, interesting, > now it is time to find out how the relay works, 12vdc goes to the coil of > the relay then passes through the coil to ground and the relay energizes > and the contacts are changed in state for open to closed, but the 12vdc > power source is from some where else going to the 12vdc fan motor and not > the switch on the dash. Now one must check the voltage patch the flow > through the relay to the 12vdc fan motor, and find the "why" it is not > present. So we have isolated the part of the 12vdc circuit that is not > working to turn on the fan with the switch. Checking the "source" circuit > breaker, it is found not to have 12vdc present. So the circuit breaker is > the bad part, it must be replaced. Now switch on the dash switch and the > fan motor runs. Great! you have fixed the problem, or have you? Did we look > into the "why" the circuit breaker went bad? This part of trouble shooting > is not always well defined and in fact may not be found. So that brings up > the question, what must happen to make a circuit breaker fail? Lose > connections are a cause. Bad ground is a cause, age of the part will > contribute to the cause of failure. > > As you can see there can be several steps and items in a system even one as > simple as this one. Trouble shooting can be VERY time consuming, but it has > to be done to make a system work. Once you have been through a few > troubleshooting procedures like this, you learn some short cuts here and > there that helps to "cut" the time factor down a bit. > > Also a thing to remember. Nothing is set in concrete when trying to find > out and repair what does not work. What I am trying to do here is show a > process that is practical, saves time and effort and cuts the cost of a repair. > > Let's not throw money at something in hopes that is will make it run. You > can sure go through allot of money doing that and still not find the > problem let alone fix it. So with a few trouble shooting steps we have > spent $3.00 on a part to make the system run, instead of spending $225.00 > in parts like new switch? new fan motor, new relay and so forth. Yes it has > cost the time to troubleshoot the system but is still cheaper on a repair > bill than throwing money at some thing. > > Will stop here for this first post and wait a few days and answer any > questions anyone may have. > > Ues I know it is a VERY simple system noted above, but there are a large > percentage of people that do not have any idea what or how. Please keep > that in mind when posting on this first post. > > Safe travels, > > Ralph and Charolette Fullenwider > 84FC35 "Ruff Diamond" > Duncan, Oklahoma >