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Need help testing stator coils 1973 mercury 9.8

M

MercuryDoug

New member
Hello,
I have a 1973 Mercury 9.8 outboard. I need some info on how to test the high speed and low speed coils.
According to your service info page for the the high speed coil it should test at 450-550 ohm and the low speed should test at 3600-5500 ohms.
My problem is that I do not what setting on my basic digital multimeter. The settings for ohms on my meter go from 2000k and 200k and 20k and 2000 and 200. No matter what setting I use I do not get those readdings. If I use the 20k setting I get on the high speed coil 0.21 ohms and on the low speed coil I get 483 ohms.
Do I need a special meter to do this testing?
Any info would be apreciated.
Thanks A Lot,

Doug
 
Any (functioning) digital multi-meter is fine.

If you are looking for 450-550 ohm's (high speed) you should select the 2000 ohm setting - the 200 is "too low" (would "peg out" on an old analog meter) and the 20K (20,000) is too high.

Likewise, when looking for 3600-5500 ohms of resistance, I would select the 20K (20,000).
 
galamb said:
Any (functioning) digital multi-meter is fine.

If you are looking for 450-550 ohm's (high speed) you should select the 2000 ohm setting - the 200 is "too low" (would "peg out" on an old analog meter) and the 20K (20,000) is too high.

Likewise, when looking for 3600-5500 ohms of resistance, I would select the 20K (20,000).
Click to expand...


Reply
i tested hs with digital multimeter set on 20k and got 0.18 and on 2000 i got 182.
i tested the ls with digital multimeter set on 20 k and 4.83 ohms .

Dont know what to make of it.
Doug
 
So a little out of spec (182 vice 450-550 and 4830 is in the range).

That tells you that the coils (bobbins, windings - pick your term) are "intact". If the resistance was off the chart that would indicate a break somewhere. The specs were written for the measured resistance at 68 degrees - higher or lower temperatures can have a little to a lot of effect, depending on the size of the wire - small wires are "naturally" MORE resistant than larger wires and the temperature effects them accordingly.

So just based on your readings, even out of spec on one side, I wouldn't jump to the conclusion that there is an issue with the stator.

Given the resistance they "should" be producing electricity, you just don't know how much.

At this point I would test/have them tested with a DVA equipped meter or a multi-meter with a DVA adapter. Any small engine shop that works on two strokes (including garden tractors, motor bikes etc - doesn't have to be marine) usually can do the DVA tests.

Your stator produces AC. The switchbox or CDM's, condenser (on older models) convert that AC to DC. All the specs for the ignition are in DC (and it's far easier to measure than AC). The DVA "acts like" the switchbox and converts the AC from the stator into DC that can be measured. There is no "short cut/jury rig" around that one - you either have an adapter or a DVA meter - neither of which is "standard toolbox gear" for the average person.

If you are somewhat remote to somewhere/someone that could do that test for you, I would personally move on with my troubleshooting. I have seen more than a few toasted stators over the years but they either worked or didn't work and if the bobbins are intact it is (probably) working.
 
Last edited:
galamb said:
So a little out of spec (182 vice 450-550 and 4830 is in the range).

That tells you that the coils (bobbins, windings - pick your term) are "intact". If the resistance was off the chart that would indicate a break somewhere. The specs were written for the measured resistance at 68 degrees - higher or lower temperatures can have a little to a lot of effect, depending on the size of the wire - small wires are "naturally" MORE resistant than larger wires and the temperature effects them accordingly.

So just based on your readings, even out of spec on one side, I wouldn't jump to the conclusion that there is an issue with the stator.

Given the resistance they "should" be producing electricity, you just don't know how much.

At this point I would test/have them tested with a DVA equipped meter or a multi-meter with a DVA adapter. Any small engine shop that works on two strokes (including garden tractors, motor bikes etc - doesn't have to be marine) usually can do the DVA tests.

Your stator produces AC. The switchbox or CDM's, condenser (on older models) convert that AC to DC. All the specs for the ignition are in DC (and it's far easier to measure than AC). The DVA "acts like" the switchbox and converts the AC from the stator into DC that can be measured. There is no "short cut/jury rig" around that one - you either have an adapter or a DVA meter - neither of which is "standard toolbox gear" for the average person.

If you are somewhat remote to somewhere/someone that could do that test for you, I would personally move on with my troubleshooting. I have seen more than a few toasted stators over the years but they either worked or didn't work and if the bobbins are intact it is (probably) working.
Click to expand...

Thanks a lot for the help.
Thats what I was beginning to think At least I got some numbers of ohms and the coils were not blown or burnt out. So I was thinking of muving on to why it wont start and make sure the points fire and there is spark now. But I think I will get a DVA equipped meter. Would be good to have.
Thanks for all your advice and help. I will post my progress with this motor.
Doug
 
If you have a use for it a DVA IS handy.

You can get a DVA adapter relatively cheap - think mine came from Harbor Freight for about 20 or 30 bucks - you plug (it) into your multi-meter and then it has it's own leads - more economical than a full blown DVA equipped meter.
 
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