help me read multi reader

[patrick4266]

I have a 1991-70hp rude, tach not working battery not charging. I have the omc manual. It says the reading on the stator wires should be 1.4 ohms. I am getting 2.1. I have two other stators that I tested with same meter, I get same results. 1985 and 1987 both 70_hp. I'm not much good at electronics so i need some help. I bought the digital read out multi meter, omhs slection is 20k-2000 and 200. I selected 200, which is the lowest. Can some one give me some advice?

 

[Vic.S]

Re: help me read multi reader

I have a 1991-70hp rude, tach not working battery not charging. I have the omc manual. It says the reading on the stator wires should be 1.4 ohms. I am getting 2.1. I have two other stators that I tested with same meter, I get same results. 1985 and 1987 both 70_hp. I'm not much good at electronics so i need some help. I bought the digital read out multi meter, omhs slection is 20k-2000 and 200. I selected 200, which is the lowest. Can some one give me some advice?

It its reading 2.1 on the 200 ohm scale it means 2.1 ohms.

But often they don't read zero ohms accurately ( unless they have a zero adjustment like the old analog meters always had)

What reading do you get when you short the two test leads together... if its nor zero subtract what you do read from 2.1. That might get you closer to 1.4.

You might have bit of resistance in your connections to the stator 0.7 ohms is not a lot.

id have taken 2.1 ohms as OK!

 

[HighTrim]

Re: help me read multi reader

edit: talked about readings but Vic covered it

From your description, you have classic symptoms of a faulty rectifier. You are going to test it right? If you need help with this let us know, or check ou the faq

 

[Vic.S]

Re: help me read multi reader

You are going to test it right? If you need help with this let us know, or check ou the faq

Yes Joe Reeves covers testing of non regulated rectifiers on the Engine FAQs board.

BUT If using a digital meter you will need to use its "Diode test" range because they dont always work on all ohms ranges for diode testing like analog meters do

If no diode test setting use the highest ( 20k ) ohms range .. hopefully that will work.

 

[patrick4266]

Re: help me read multi reader

So you guys think 2.1 is alright? The first thing I did was check the rectifier. I have 3 of them but I guess all 3 of them or bad. One of them shows 10.40 and .0 on the yellow wires. Another shows 1.4 on yellow wire with stripe .0 on the other. The last rectifier shows.0 on both yellow wires. Seems they are all bad? If you guys think my stator is alright, I will order a new rectifier?

 

[jtexas]

Re: help me read multi reader

you may have misunderstood the test procedure...you need 2 readings from each yellow wire to the rectifier case (ground), and 2 from each yellow wire to the red wire, for a total of eight readings.

--see vic's description below--

The actual numbers here do not matter, this is a "pass/fail" test -- either there is a "reading" (some number, even zero) or there is "no reading". If the rectifier is good, each wire will have a "reading" on one test and "no reading" on the other.

"No reading" means "open circuit," or "not connected at all"; most meters show "0.L" for that -- what does your meter show when neither probe is touching anything? That would be "no reading".

"0." probably means "almost no resistance", which is a very good connection.

Something to keep in mind when measuring resistance: if the metal probes are touching your fingers, the meter will measure the resistance of your body. This will be somewhere in the neighborhood of 1 to 2 million ohms, give or take (it goes down if you're lying, or sweaty).

 

[Vic.S]

Re: help me read multi reader

Do not understand the readings you are quoting.

Follow this ( which is a modification of Joe Reeves instructions)

Remove the rectifier wires from the terminal block. Using a digital multimeter set to the diode test range, connect the black lead of the meter to the rectifier case (ground), then one by one, connect the red lead of the meter to the yellow, yellow/gray, and if present, the yellow/blue wire. Now, reverse the meter leads and check those same wires again. You should get a readings in one direction, and none at all in the other direction.

Now, connect the black lead of the meter to the red wire. One by one, connect the red lead of the ohm meter to the yellow, yellow/gray, and if present, the yellow/blue wire. Then reverse the leads, checking the wires again. Once more, you should get readings in one direction and none in the other.
​

If you have an analog meter use any ohms range. If you have a digital meter without a diode test range try the highest ohms range but be suspicious of the results if you get all "no readings"

The important thing is that for each pair of wires tested you must get a reading on the meter in one direction but no reading ( infinite resistance) in the other.

 

[Vic.S]

Re: help me read multi reader

Post deleted.. reason below

 

[jtexas]

Re: help me read multi reader

thanks vic, hope I din't confuse anybody more than necessary -- I'm gonna edit that out, and refer to your description.............

 

[patrick4266]

Re: help me read multi reader

Here's my latest readings. 1.2 ohms on yellow lead #1 same reversed. Yellow lead #2 no reading, same reversed. Red to both yellows no reading, same reversed. I tried setting the multitester on different ohms scales but the 200 scale is the only one that will read for me.

 

[HighTrim]

Re: help me read multi reader

Dont run the motor until the rectifier is replaced or disconnected at the bare minimum. Sounds like you found your problem

 

[patrick4266]

Re: help me read multi reader

Do you think the stator is alright? The book calls for a reading of 1.4 ohms +or-.01ohms but I am getting 2.1 ohms but some one said that is alright?

 

[jtexas]

Re: help me read multi reader

If you were a marine tech working on a customer's motor, you'd pull the flywheel & replace the stator, and add it to his bill. Luckily, you can just install a new rectifier and see if it works.

[btw, when that multimeter wears out, replace it with one that says "autoranging" on the package]

 

[patrick4266]

Re: help me read multi reader

Thanks jtexas. How much those auto reading meters cost? Mine is real cheap 17 dollars.

 

[Vic.S]

Re: help me read multi reader

Thanks jtexas. How much those auto reading meters cost? Mine is real cheap 17 dollars.

You call that cheap I got two for ?5 from a popular electronics component suppliers in the UK.

Not seen the need for an autoranging one yet.

 

[jtexas]

Re: help me read multi reader

I got one at o'reilly's for $20, walmart has one for less than $25...not the best but good enough. Got a good price for a craftsman on ebay...a really good one until that last time I dropped it.

 

[patrick4266]

Re: help me read multi reader

I just put on my new rectifier and it's charging great. Thanks everybody

 

[patrick4266]

Re: help me read multi reader

What threw me off is I had 3 rectifiers and they were all bad. They must be easy to fry.

 

[d.boat]

Re: help me read multi reader

What threw me off is I had 3 rectifiers and they were all bad. They must be easy to fry.

I've heard even a loose battery connection can fry one. Certainly a momentary reverse hook up on the battery can.

 

[Vic.S]

Re: help me read multi reader

I've heard even a loose battery connection can fry one

Yes for the same reason that disconnecting the battery while the engine is running.
The interruption causes a voltage surge which can blow the diodes etc