Briggs 42A707 Stator output measurement

[Rivets]

This manual may be of some help to you. It shows testing procedure and specs for most Briggs charging systems. https://www.briggsandstratton.com/c...n_us/Files/FAQs/alternator_specifications.pdf

 

[StarTech]

Rivets what OP is wanting or needing is actual resistance of the windings. He has it already off. Once he the resistances he can determine if the is a short in the windings to ground. I am sock with ice at current time so I can't get to the shop.

 

[Rivets]

To my understanding there are no resistance specs for the stator. Most of the time you are looking for either windings which are shorted or open. This manual has all tests Briggs recommends for troubleshooting their charging systems. https://www.briggsandstratton.com/c...a/en_us/Files/FAQs/alternator_replacement.pdf

 

[StarTech]

To my understanding there are no resistance specs for the stator. Most of the time you are looking for either windings which are shorted or open. This manual has all tests Briggs recommends for troubleshooting their charging systems. https://www.briggsandstratton.com/c...a/en_us/Files/FAQs/alternator_replacement.pdf

Which is quite stupid is one sense and lazy in another. All enamel coated wire has resistance, just very, very low resistance but it is still measurable. It is going to be probably under one ohm but I won't know a day or two. Actually I need to find my milli ohm meter. It is packed away in boxes that I never have opened since I move to my current home 6 years ago.

It just I never got around to investigating the specs here myself. Even a few tenths of an ohm is enough to tell if there are a short or not. But the easiest way is to test for output voltage and current.

It like the Magnetron coils they don't issue any specs for them either but there is still some specs that can be checked; although, the electronic trigger itself can't be fully checked. They also say the high tension lead is not replaceable but it is.

Things thawed out just before dark but was blowing near freezing rain. Now it is below 18F with snow falling and the garage door is froze shut. It going to doing this for the next week if the forecasts hold.

 

[StarTech]

Okay here a rough measurement of the ohm-age.

AC circuit is about 0.4 ohm
DC circuit before the diode is about 1.0 ohm.
My meter leads registed 0.4 ohms which was deducted to obtain the above numbers. I still haven't found my milli-ohm meter.

 

[Bentoolong]

Okay here a rough measurement of the ohm-age.

AC circuit is about 0.4 ohm
DC circuit before the diode is about 1.0 ohm.
My meter leads registed 0.4 ohms which was deducted to obtain the above numbers. I still haven't found my milli-ohm meter.

Are you measuring the two sides individually to ground? So basically one wire (at connector) to the metal "frame" of the stator.
When you say before the diode are you saying to measure without the diode in the picture.
I've got a decent Fluke DVOM so I should be able to measure this.

 

[bertsmobile1]

The problem is , new out of the box you get a massive difference in the resistance measurements.
When I first kicked off I tried doing that as I had boxes full of supposedly good electricials ( most weren't) ,
Ended up using a dead set of cases and an old crank hooked up to an old washing machine motor to do the testing of alternators & magnetos.
Even with new stuff the variance due to contact spot & pressure can be more than the actual resistance .
For example one will have the wire soldered in direct contact with the laminations and that will read lower than one which is embedded in a blob of solder so you have copper>solder>steel couples to deal with.
The next one will have a crimp and be different again .

Back when I wore a dust coat & got paid by the hour to attempt to get students to think , one of the fun things was to make them design experiments.
Very early in the year was galvanic corrosion & protection.
In 15 years never had a student who could make repeatable eV measurements but fortunately there were a few who could do the maths and some even understood it.
BEfore we became a saussage factory we used to get the students to make a differential galvanometer which they would use over the following 2 years

 

[StarTech]

Are you measuring the two sides individually to ground? So basically one wire (at connector) to the metal "frame" of the stator.
When you say before the diode are you saying to measure without the diode in the picture.
I've got a decent Fluke DVOM so I should be able to measure this.

Yes the Fluke should give decent readings vs those el cleapo $10 meters.

Individually of course as they are two different circuits. And yes of course without the diode. Basically you are just looking either a dead short to ground or or an open circuit. Individual winding shorted to each will generally very hard to detect at this level of resistance. These reading are from an old known good stator. (1994-98 vintage stator)

Also varying amount of meter lead tip pressure will also vary the reading as you breakthrough the oxidization layers of the contact points.

It is to note that on first version of these dual circuits stator Briggs would fuse the circuit to them which was a 7.5 fuse but that was quickly deleted from the circuits. Original the fuse was to save the stator and diode from reverse voltage application. IE the battery being connected backwards. But most are not fused and are just fried. They figured the one that installs a battery backwards should pay a price for doing it.

 

[StarTech]

Bert, I have dealt with transformers that have nothing but several ferrite cores stacked on two 1/2 long metal tubes which form a center tapped primary with three very short loops enamel wire for the secondary so the resistance is not even measurable at DC. But at the operating frequency the impedance is measurable although not safe to do so except at very low wattage. Quite a bit of RF radiation at 300 RF watts. But with right size components we can push nearly 500 watts through these transformers. As we get to higher operating we get down to short flat strips of metal to make inductors.

When making these transformers you got to very carefully not to scrape the enamel wire coating which was why I prefer the amour coat version; though, it did change some of the operating specs as induced capacitance and inductance changed so that had to be compensated for.

Personally I prefer the tubes as they were much easier to match up to 50 ohm loads except were not too usable for mobile amps. Beside vacuum tubes are virtual none existence now though a few ceramic tubes are still available.

 

[Bentoolong]

Yes the Fluke should give decent readings vs those el cleapo $10 meters.

Individually of course as they are two different circuits. And yes of course without the diode. Basically you are just looking either a dead short to ground or or an open circuit. Individual winding shorted to each will generally very hard to detect at this level of resistance. These reading are from an old known good stator. (1994-98 vintage stator)

Also varying amount of meter lead tip pressure will also vary the reading as you breakthrough the oxidization layers of the contact points.

It is to note that on first version of these dual circuits stator Briggs would fuse the circuit to them which was a 7.5 fuse but that was quickly deleted from the circuits. Original the fuse was to save the stator and diode from reverse voltage application. IE the battery being connected backwards. But most are not fused and are just fried. They figured the one that installs a battery backwards should pay a price for doing it.

Well I chopped the diode off and I checked resistance in both directions. Nothing. I should have some current in one direction but not the other. I have a diode pigtail ordered. I'll take a chance that the diode is the issue.
The rest of the stator looks good. I don't see any burned spots. Since the black (for lights) had good voltage, I'm gonna go out on a limb and say that the diode is the source of the "no charge" issue.

I should have this back together next week and I'll loop around with results when I know.

Also, the crank seal was leaking and the stator and flywheel were pretty grungy because of that. I'm replacing the seal and cleaning up things nicely before reassembly.


Later,
Bentoolong