Electrical Systems 101.1

[B~C]

Ok, here it goes, I'll keep pecking away at this project but for maximum impact you really need to attend one of the required labs. To provide that proper school like atmosphere I crafted up a syllabus (Brock! spit that gum out)

[B~C]

COURSE NAME: BASIC ELECTRICAL SYSTEMS 101.1
Instructor: Professor Bernt Phuse
Meeting times: to be arranged
Meeting Location: Jerrell Cove, Cathalmete
Credits: .02
Required tools: Auto ranging, 10 amp fused Digital Multi Meter (DMM )

COURSE DESCRIPTION;
This course will cover the basic principles of electricity and DMM use. Upon completion of this course the student will;
* have an understanding of the relationship between amperes, Ohms and volts
* be able to measure voltage, amps, ohms and continuity using a DMM
* understand the concept of voltage drops and be able to measure them
* be able to troubleshoot a basic electrical circuit
* perform basic troubleshooting procedures of batteries, starting and charging systems using a DMM

GRADING;
Grades to be assigned impartially based solely on the quanity and quality of adult beverages provided

[B~C]

Digital Multi Meters- you need one, you may just not know it yet, these things are your eyes into the electrical circuit.

Back in the old days, folks used analog meters (those rascals with the needles that read wrong if you looked at them crooked) to measure volts, amps and ohms with each quantitiy requiring a different meter, but, alas, with today's new technology, they've wrapped all three meters up into one with a digital display, thus the term digital multi meter. Analog meters still have their place and are great for some applications but they are not as accurate and are more intrusive in the circuit being tested. More intrusive in the circuit? What the hell are you talking about? The analog meter requires a bigger taste of what's happining in the circuit in order to take it's reading, in a computer circuit that's dealing in Milli amps, this can be fatal to the computer. A decent DMM just needs a small taste and doesn't disturb the circuit as much, therefor is not only healthier for the computer, but, is also more accurate.

DMM's range in price from $10 to over $400, a real cheap model is just that, cheap junk. On the other end of the cost spectrum are models with more functions than the normal human will ever figure out or need. A good DMM can purchased for $40-60, the Sears Craftsman model 82040 is a fine unit at a reasonable price, Radio Shack also has some good values on DMM's. When shopping for a DMM, make sure it has the ability to measure amps through an internally fused circuit (most have 10 amp fused capability), dont forget to buy extra fuses for the durn thing. Most meters are auto-rangeing, meaning the meter will fing the correct scale for the display. This is a good thing BUT you must make note of the units being displayed when you take your reading

[Captains Cat]

Ken, it's a little far fromthe right coast for us Easties but I'd like to follow by internet. That's how I got all my degrees! (just kidding) This will sure beat the lick, touch, YOUCH!! method...

[Anita Marie]

I have a couple of digital multimeters, one with a clamp on amp meter. I will bring them along so you can use them in your lab on the Blue C.

[Da Nag]

Another good resource for DMM's - eBay. Picked up a nice, new in box Fluke for about half off last year.

Here's a question for you, Science Guy - why aren't there any of those nifty and cheap voltage detectors for DC like there are for AC? You know - the little ones shaped like a pen, that when activated in the vicinity of a hot wire, beep or light up...

[B~C]

Cvinroot, it just so happens that "distance Ed" is the latest buzz

PS_Rick, take a gander at the amp clamp, many of them are only good for AC circuits

Bill, E-Bay, Fluke, GOOD stuff...when I worked at the Cat dealer there was a program where if you passed their electrical test you could buy a Fluke 87 for 1/3 the cost...awsome meter

To answer your question regarding cheap voltage detectors; An AC current is constantlly changing from + to - voltage, the magnetic field surrounding the conductor is also building and collapsing. The cheap voltage detectors and amp clamps sense that magnetic field. The DC current has a steady voltage so the magnetic field is stable...cost much more to make a tool that can make sense of the steady magnetic field.

twas a crazy day today, tune in tomorrow for more serious stuff

[Wheeler Dealer]

Ken,

I need help in understanding the electrical connections on my 16'. I mounted my transducer for the depth finder and ran in up through the gunnel. Got the nice little cable holders to make it nice, neat and proper. I also installed a cigarette lighter receptacle for all of those cool 12 volt boat tools and toys. Here is the neophyte part of my existence. Okay, I am now going to expose my soft white underbelly. I know that electricity was put on this earth just to scare the hell out of me. There I said it and I feel better . I carefully looked over my manual but am still unsure where to attach the common. If I'm right the hot goes to the middle post on the switch side of the buss. Where does the common go? I have learned household electrical over the years and want to know enough to be able to do simple installs like this.

If you can get me through this, I promise not to be brain washed by Mike to throw rocks at Catlameth . Jon

[Pat Anderson]

So, I read this a couple of days AFTER buying my DMM (on the trip home from Squalicum after returning from Sucia last Sunday) - a $19.95 Radio Shack jobbie. It doesn't seem to be cheap junk - it is not auto-ranging, nor is it internally fused. Still, compared to the analog Murata that I have had in my home kit for umpteen years, it is LIGHTYEARS ahead. I played with it a little bit Sunday afternoon, and it would have been invaluable on Sucia...On the boat, I will just keep the DC meter on the 20 volt setting, and it should do me fine, no? Or do I NEED to go buy the next RS model up, which as I recall, was something like $69.95...

[B~C]

WD Jon, not quite sure what you're wireing...there should be another buss bar for ground connections amongst the wiring mess behind the helm.
Pat, that meter should be fine for what you're doing.
gotta go, relative invasion in progress

[True Story]

HEY BCK. Geez....an opportunity to pull my head out of the sand. Hmmm....... pretty tempting. Nah. Ignorance is bliss ya know. Tell you what, if we are able to attend either of the functions, I will be there with the amper ohmer volter DMM meter thingy in one hand and a six pack of animal beer in the other. It's nice of you to offer this help.

Last summer in Port Angeles, I spent well over three hours trying to figure out why my bilge pump quit working. Running new wires, thinking about running up to the marine store to buy a new pump, head scratching, cussing and all of that kind of stuff until it dawned on me that the durned thing must have a fuse somewhere. I finally found the fuse in the starboard lazerette in one of those "water tight" black holders with the orange gasket. I popped the top off and wondered what all the green stuff was about. Well, as you likely figured out about four sentences ago, the fuse had broken. Cleaned up the gunk, put in a new fuse (still can't beleive I had a spare), reconnected the wires, apologized to the wife profusely and we were in business. I did end up changing the fuse holder when we got home.

I've been thinking about what I could offer the group next time we're at a get together. Kind of like what you are offering and I figured it out. Reclining Basics Primer. In the chair, on the couch, the floor, at work, at the movies, shopping with the wifey, on the boat, fishing. Just about anywhere you might be or anything you might be doing, I've got it figured out. Not sure I need any form of compensation though cause all any one needs to do is to watch and observe. Thanks again for being willing to share some of your mechanekin skills.

[stevej]

Good job Ken, troubleshooting the 12V systems on our CD's can be relatively simple with a few tools. One feature I like on my Sears DMM (still want to call em a VOM) is the audible connentunity indicator. Saves a lot of looking back and forth as you trace circuits.

If you don't mind a couple of suggestions that would be quick to cover in class
Tools - couple of good gauge specific wire strippers, a high quality crimper as well as a selection of heatshrink tubing and tie wraps are a must. Check out http://www.jensentools.com/

Crimped VS soldered/crimp connections - Be happy to give a demo on correct soldering techniques. There are pros and cons for both approaches.

General discussion on CD wiring and lessons learned

Don't know about the newer CD's but on Shearwater the factory wiring was marginal at best. Confusing to work on, difficult to expand and done with low quality componets. Believe I spent about $500 dollars for parts and almost 100 hours labor (I'm slow but do good work) on the rework of the system.
Looking forward to class

stevej

[Rock-C]

Stevej
Last summer i viewed your photo album of Shearwater. The photos of your electrical system was the inspiration I needed to tackle the rats nest in Rock-C. I have before and during pics but I need to take a photo of the completed job. It is not as neat as yours but it's a big improvement. The best part of the project is I now have a better understanding of whats going on down under. That should make troubleshooting future problems a lot easier.
Thanks.

[Jon - CLou]

Sorry teacher for being late for class, I was out fishing. Same excuse I used 30 years ago.

Ken, my tachometer has been acting real goofy lately. It's only about a year old and works correctly 95% of the time. Here's the problem: sometimes when initially starting up the motor, the tach will show really high readings (example: when high idle should be around 3000 rpm's, the gauge reads 5000 to 7000 rpm's.) I thought it might be a bad ground, so I relocated the ground(different post on the bus bar) and it worked for a while. Now it's back at it again. What do you think?

[B~C]

Good ideas Steve...soldering and crimping are a lesson themselves and tools..so many tools so little time. If anybody feels the desire to jump in here and crank out a lesson or two, feel free, It was my hope to have a thread chocked full of electrical learnin so a person with no electrical background could read up and be able to chase those electrical gremlins around their boat ( or at least chase them over to Mike's boat). I'm all for team teaching, it'll make this a better learning center.
Jon, about all I can offer up on the Tach is to check the hot side and the ground side, if all is well then either the sender or the head is kaput.
Check the Ohm value of the sender (whenever a person checks the ohms in a component it must be removed from the circuit and the power off) most speed sensors have a ohm reading of between 500 to 4,000 ohms
Check the adjustment of the sensor, it should be almost touching the tone ring.
Check the output of the sensor, disconnect the sensor and connect your DMM in the ACV mode to the sensor wires, you should see the AC voltage increase with speed. you could also remove the sensor & with meter attached, pass an iron object in front of the pickup, voltage should vary with regards to how fast (and close) you wiz by with the chunk of metal......Being that this is an intermitten problem you best test everything when it's on the fritz. If the sensor and wires are a good then that leaves the tach itself and then you're into some solid state voodo electrical grief with the only cure being cash.

tune in next week, hope to crank out some material on volts, amps, ohms, watts and my favorite, voltage drops. Voltage drops are the best method of finding bad connections and intemitten problems