Electrical test equipment

Mon Nov 17, 2008 11:07 am

Having been an electronics technician for 40+ years I have quite a bit of electrical digital, test equipment, including analog, digital, and precision digital voltmeters. I also load testers for batteries, clamp on ac and dc amp meters that allow testing current flow without interrupting circuits, even a frequency counter (real handy for adjusting AC power generators). Below, are the items I grab most commonly for trouble shooting cub electrical problems. One is a 6/12 volt test light, the other is a spark tester. The tester has a ground clip for attaching to the ground on machine, and the other end accepts a spark plug wire. The gap is adjustable by turning the ground lead, and allows you to check for spark length. An spare spark plug wire allows it to be connected directly to the coil tower for testing there. Not only are these the items I grab most often, but they are the cheapest ones I own. The light is about $8 and spark tester is around $6 at most any auto parts store.

Image

Re: Electrical test equipment

Mon Nov 17, 2008 11:21 am

Throwing in one more cheap piece of test equipment. Multimeter.

The cheap ones sell for less than $15-, usually under $10-. The cheap ones work well until you make a mistake and switch the dial under load. Then it's time to buy a new one.

Looks to me like there should be a thread in the "How to" section of this board on test equipment, applications, and how to use them.

Re: Electrical test equipment

Mon Nov 17, 2008 12:12 pm

Hey... I have seen that spark tester before! Used that very one (or one that looks exactly like it!) to troubleshoot ol' Merlin last fall!!

I second John's opinion that these are some GREAT and CHEAP tools to troubleshoot a cub!

Mike in La Crosse, WI

Re: Electrical test equipment

Mon Nov 17, 2008 3:09 pm

Yup, when is the how to class? Could be a good one for DocFest. :D

Re: Electrical test equipment

Mon Nov 17, 2008 3:48 pm

Eugene wrote:Throwing in one more cheap piece of test equipment. Multimeter.
Agreed, and I have both cheap ones and good ones I use. The 2 items I showed though will handle around 75 to 90 percent of electrical problems encountered on old tractors or old trucks and cars. charging problems will frequently require the use of an analog voltmeter though.

NAPA online shows a part number of BK 7002015 and price of $16.99 for the tester. your local store may have it cheaper though. I bought mine at Autozone for around half that.

Re: Electrical test equipment

Mon Nov 17, 2008 4:21 pm

Use of both items is pretty simple, which is why I like them being simple minded.

To use the light, simply connect the alligator clip to a good ground, and touch a terminal, fuse, etc in question. Example, lights not working: First touch test lead to hot side of battery to make sure your ground clip is making a good connection. Then with light switch on touch to screw on back of light housing. Light comes on, problem is inside head light. No test light, problem is toward light switch. Next move to light switch and touch to headlight wire terminal there. Light, probably broken wire between there and head light. No light, touch to lug the terminal attaches to. if light, clean connection, no light move to fuse. Touch both ends of fuse. if light on one end, replace fuse and clean holder clips. If light at both ends test again on clip instead of fuse. light on one end and not other, clean clips. Light on both ends, switch is probably bad. No light at either end of fuse, check wiring coming to light switch.

To check for power to ignition, touch to switch side of coil (switch on), which is normally the - side on 6 volts, and + side on 12 volts. No light, move toward ignition switch (checking both ends of dropping resister if you have one), keep moving toward battery until light comes on. When it lights you have passed the problem, whether it is broken wire, bad switch, etc.. If light on hot terminal, move to distributor side of coil. light should go on and off 2 times per revolution when cranking engine, preferably by hand so it is easier to see. Light should be on when points open, and off when points close. Light off all the time, disconnect wire to distributor. If light comes on them, you have a short in distributor, maybe condenser, or points stuck shut, or rarely a shorted insulator where wire enters distributor. If light does not come on, coil is bad. If light is on all the time, check for broken wire between coil and distributor, points burned or dirty so they do not make contact, etc.

For the spark tester, connect it to the tower on distributor coil or mag coil using an extra spark plug wire. Set gap of tester between 1/4 and 3/8 inch. Turn ignition on and crank tractor. Should get spark 2 times per revolution for 4 cylinder engines. if no spark, trouble shoot coil. points, wiring, etc. If proper spark, reconnect coil and connect tester to distributor cap either using the spare wire, or plug one of the spark plug wires into the tester. You should see a spark every other round. If no spark, check cap, rotor, and spark plug wires. If spark, check spark plug. If you get a spark there, check carb. and fuel supply. :(

Re: Electrical test equipment

Mon Nov 17, 2008 4:50 pm

If Ralph or Russ Leggitt are around you don't need the spark tester........ :wink: :wink: :wink: :wink: :wink: :lol: :lol: :lol: :lol: :lol:

Re: Electrical test equipment

Mon Nov 17, 2008 5:00 pm

Cub-Bud is pretty good at load testing too. :tears:

Re: Electrical test equipment

Mon Nov 17, 2008 6:11 pm

This proves that anyone can be a helpful member. Even Old Man Puckett is a valuable asset on this board. Seriously, I and the rest of us mechanically and electrically challenged Cubsters appreciate posts like this. This sort of stuff is what we ask those stupid questions about and this helps us out while not making our shortcomings so visible. We need more posts like this. Thanks again to all you folks, like EJP and Bigdog, who patiently answer questions every day for us dummies.

Re: Electrical test equipment

Mon Nov 17, 2008 8:06 pm

Rudi, this looks like a 'Tip of the week.'

Bill

Re: Electrical test equipment

Tue Nov 18, 2008 12:08 am

Eugene:
Eugene wrote:Looks to me like there should be a thread in the "How to" section of this board on test equipment, applications, and how to use them.


Excellent suggestion. It would make sense to me that our Forum Electrical Guru's get together and write up a bunch of these How To Use Electrical Test Equipment to Diagnose Electrical Problems on Your Cub! Beginning with EJ's last post.

Sounds like the beginnings of a whole chapter. :idea: :idea:

EJ: could you elaborate with pics etc... remember KISS for us challenged types ok?

Bill: Yup tip of the week but far better in the CBoK in the How To Forum and in the On-line reference Library above.

Re: Electrical test equipment

Tue Nov 18, 2008 12:38 am

Sorry Rudi, but I understood it all... :) EJP even laid out a good troubleshooting path for the whole ignition system in a short space.

I tend to use a little digital meter, but a test light is easier to work with and cheaper.

Thanks EJP!

Re: Electrical test equipment

Tue Nov 18, 2008 7:22 am

Lary:

I understood all of it as well... mostly because I have learned this the hard and long way... but that is beside the point. So many of us are visual learners and need to see where and how to conduct the test. So to make it not just a good teaching aid, but a superior one, pictures should always be part of the lesson.

Re: Electrical test equipment

Tue Nov 18, 2008 7:27 am

When testing a mag :lol:
It depends on how high ya jump off the floor :wink:
If it is a foot or more then the Mag is HOT :{_}: :{_}:

Re: Electrical test equipment

Tue Nov 18, 2008 8:19 am

I was just busting your chops Rudi... Back when I was helping folks troubleshoot machines over the phone the technology (photos etc) today would have been a huge help. The visual help is part of why I find the parts manual so indespensible when working on a Cub...