How to properly use a multimeter on a TR?

[tdskip]

Nice fat slow pitch down the middle plate for a couple of you guys... Any good write ups? Any tasks where you immediately reach for one?

 

[poolboy]

I use the simple 12 test lamp a whole lot more than a meter. I guess that so far I've just been concerned with whether or not I actually had a circuit. The one exception was when I installed a Pertronix Ignitor.
It is functional when voltage is between 7 and 14 volts. I used the meter to determine the voltage supply in the ballast resistor wire.
I know there are plenty of other uses where simply knowing whether or not there is a circuit is adequate, so I'm not discounting the use of a VOM, so please don't get me wrong.

 

[TR3driver]

If you can, get ahold of Dan Masters' electrical book for the TR6. It has a whole section on troubleshooting that applies almost as well to TR2-4 as it does to TR250-6. He said he was going to publish a TR2-4 version, but AFAIK that never happened.

On the road, I only carry a DMM ("shirt pocket" model from HF plus a couple of clip leads) so I do reach for it whenever there is an electrical problem. The voltmeter tells you if voltage is getting to your device (same as test lamp, just a little harder to read plus one caveat). Ohmmeter is great for testing fuses (I've had fuses that look fine but won't carry current), bulbs (ditto), etc. It won't directly measure enough current to be useful, but there are lots of ways to get some indication of current out of it.

The one caveat is that modern digital meters are very sensitive on the voltage range. If there is no load on the circuit, they will frequently indicate the presence of voltage even with the switch turned off, fuse blown, bad connection, etc. So the trick is to have the load connected when you check the voltage getting to it. One of the nice things about the old incandescent test lamp is that it is enough of a load itself to usually not have this problem.

 

[Geo Hahn]

The other companion piece I would recommend is the "Lucas SERVICE MANUAL FAULT DIAGNOSIS". It will walk you thru using the multimeter to test & adjust all the various electrical components on the TR. Do not know if it has been scanned & put on the web. Copies may still be available from some of the usual sources.

Harbor Freight currently has a multimeter on sale for $1.99 -- at that price I get several -- for workbench, each car and yes even the shirt pocket.