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Join Date: Feb 2001
Location: Bend, OR, USA
Posts: 761
Will Someone Teach me to Read Ohm meter

A lot of talk on various 914 sites lately about multi meters and trouble shooting FI. I need to use one on my L-jet system. Occurs to me I use my meter for voltage sometimes but mostly for continuity checks, so I never actually "read" the K Ohm scale.
First, does it read Ohms X 1000? People talk of measuring 28 to 32 Ohms resistance. Does that really mean 28000 to 32000? If not, it would be almost impossible to distiguish between 28 and 32 on my meter. My meter's scale runs form 0 to infinity and center is about 2.5. Is center 2500 Ohms? I need a teacher!
Old 03-23-2002, 12:19 PM
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most multimeters have a number of resistance settings,Rx1 Rx10 Rx1K the devise will adjust for the different scales. practice with a single element light bulb(tail light,dome light what ever) check the readings at different settings, and always save the little manuals for further reference.before you start taking resistance readings always "zero " your multimeter with the ohms adjust feature. touch the leads together and make the indicator or l.e.d read "0" on the ohms scale.

meter set to Rx1 what you read is the number of ohms 25 is 25.Rx10 multiply by10 so if you read 25 on this setting,25x10=250 ohms,if you're set on Rx100 then the number of ohms is 2500.

Last edited by Kevin Powers; 03-23-2002 at 02:05 PM..
Old 03-23-2002, 01:54 PM
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Thanks Kevin. Unfortunately I have a simple (read cheap) Radio Shack non-digital meter. Reads only volts and ohms. I can zero the needle with the adjuster wheel and leads touching. One lead plug is labled Ohms and the other is labeled K Ohms. Scale is labeled K Ohms. What is resistance when needle is centered at 2.5?
Old 03-23-2002, 02:25 PM
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Harbor Freight tools sells a digital muli-meter for around $5 on sale that reads several different scales of resistance, as well as most other functions. I tested it against a fluke meter at work, and it was pretty accurate. for that price you can throw it away and buy a new one when the battery goes dead.
Old 03-23-2002, 02:37 PM
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jim, does your multimeter have a knob that you turn to perform dif functions? when you turn it to the ohms feature is there only a Rx1k (1000) setting? look closely. mine is a analog r.s. model too. on mine the ohms scale is in green onthe top of the display area. the dc volts is in black and 2.5 volts is in the the middle of the scale. i think that is what you are looking at. if your mm has a number of lead plugins make sure one of your leads are in the one with the ohms symbol, sort of an upside down u.
Old 03-23-2002, 03:21 PM
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Junk the rat shack meter. Get a good digital meter from Fluke or
Triplett. You cannot beat the accuracy of a good digital meter.
You can get them to check resistance, capacitance, diodes, temperature, transistors and not to mention voltage, current and
continuity. All of this is helpful in troubleshooting automotive electrical systems.
Old 03-24-2002, 07:21 AM
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Jim,
Sounds like that Radio Shack ohmmeter you have is a vintage one. Here's one more reason to donate it to a museum and buy a digital one. Aside from the digital ones being quite inexpensive these days, there is a difference in performance between the old analog meters and the newer digital ones, something called input impedance. What this refers to is that the meter is effectively a resistor itself, and if it's resistance (input impedance) is low enough to be close in value to the resistance it's measuring, it will dilute the accuracy of the reading.

The old meters used to have input impedances specified something like "20,000 ohms/volt", which is not so hot by today's standards. Most self respecting digital meters today have an input impedance typically of 10 million ohms, which means the meter is MUCH less likely to influence the circuit it is measuring.

In addition, the digital meters will answer your question about reading "K-ohms". Most of the digital meters auto-range, and tell you what multiplier they are using. For example, if your meter sez "1.28 K" , that means 1.28 x 1000, or 1,280 ohms. If it sez 1.28 M, that means 1.28 x 1,000,000, or 1,280,000 ohms.

Good luck, and by the way, it's very poor form to try to measure the ohms of a circuit that has any current running thru it; in fact, that's a great way to toast that vintage analog meter of yours, so your wife can't argue with buying your new digital one .
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Yellow '76 914 3.2
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Old 03-24-2002, 09:30 AM
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