ohms meter for coils

[liz873]

OK next question. What two settings should my ohms meter be set at for testing primary and secondary windings? Saw Doug Penn's vidoe on utube , he confused the heck out of me with the settings. Does it matter if coils still hooked up to points and condensers?

 

[Chris1956]

Re: ohms meter for coils

Yes, disconnect points and condenser. Primary coil will have very small resistance. Use Rx1 setting, and expect near short. Resistance can be less than one ohm.

Secondary coil will have a lot more resistance, maybe a couple of hundred ohms. use the Rx10 setting. Obviously I do not have the ohm values handy. You might post motor HP and year, and someone will give exact values.

 

[liz873]

Re: ohms meter for coils

Yes, disconnect points and condenser. Primary coil will have very small resistance. Use Rx1 setting, and expect near short. Resistance can be less than one ohm.

Secondary coil will have a lot more resistance, maybe a couple of hundred ohms. use the Rx10 setting. Obviously I do not have the ohm values handy. You might post motor HP and year, and someone will give exact values.

Its a 1972 6 hp johnson. I tested 1.0 ohm or less on primary using 200 setting . but I have a digital meter so setting has to be set at 20K when testing secondary winding - giving me 4.0 I believe it is 4,000 ohms. Ive heard you can only use an analog meter for this test because of the settings?

 

[boobie]

Re: ohms meter for coils

Not to pea on your parade here but if the ohm readings are correct the only way to test a coil is with a coil load tester. That way you can test for any high voltage leakage. I've see them where all the ohm values checked out but when you load them you have a leak to ground.

 

[metriccrescentwrench]

Re: ohms meter for coils

Ive heard you can only use an analog meter for this test because of the settings?

Poppycock. Resistance is resistance, no matter how you measure it. Where the old analog meters would be different from newer, more accurate ones is measuring very high resistances because the old meters had a very low input impedance (i.e. the measuring circuit would suck up some of the current and give a misleading reading). That shouldn't be an issue at all with only the few thousand ohms we're talking about.

the only way to test a coil is with a coil load tester. That way you can test for any high voltage leakage.

That's very true. One thing that SOMETIMES shows a problem is to run the engine on muffs after dark so you can more easily see an arc.

 

[F_R]

Re: ohms meter for coils

Not to pea on your parade here but if the ohm readings are correct the only way to test a coil is with a coil load tester. That way you can test for any high voltage leakage. I've see them where all the ohm values checked out but when you load them you have a leak to ground.

Absolutely true. However, a resistance test is a good preliminary test. And sure a lot cheaper than a dedicated coil tester. The primary is virtually never bad, but the secondary often is. And if the secondary is open, you might as well scrap it, even though it MIGHT still work. But it won't work for long because it will be arcing internally and will get worse and worse as it does.

 

[liz873]

Re: ohms meter for coils

Absolutely true. However, a resistance test is a good preliminary test. And sure a lot cheaper than a dedicated coil tester. The primary is virtually never bad, but the secondary often is. And if the secondary is open, you might as well scrap it, even though it MIGHT still work. But it won't work for long because it will be arcing internally and will get worse and worse as it does.

I figure my priamary is good both coils are about 1 ohms. But I get 4 ohms on secondary of both coils using a different scale on my digital meter (20K). - I belive it is 4,000 or 8,000 ohms. Not sure how to convert it. I guess better get analog meter just to be sure.

 

[liz873]

Re: ohms meter for coils

Ok done deal. checked operational manual online, 1 on th 200 scale is 1 ohm for primary-thats good and 4 on the 20K scale is 4,000 ohms for secondary windings. All secondary windings on these old outboards measure in the thousands. Some people dont convert them and use numbers without multiplying them which is incorrect. I believe 4,000 is a good coil. Anyone have similiar readings for secondarys?

 

[lindy46]

Re: ohms meter for coils

Anywhere between 4000-7000 should be good.

 

[F_R]

Re: ohms meter for coils

Ok done deal. checked operational manual online, 1 on th 200 scale is 1 ohm for primary-thats good and 4 on the 20K scale is 4,000 ohms for secondary windings. All secondary windings on these old outboards measure in the thousands. Some people dont convert them and use numbers without multiplying them which is incorrect. I believe 4,000 is a good coil. Anyone have similiar readings for secondarys?

All coils are not created equal. Depends on mfr. But 4K (4000) is a good average. I usually just say "several k-ohms". It is the way-low or way-high ohms that are a concern.