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Briggs 42A707 Stator output measurement

#1

B

Bentoolong

This mower won't charge. I have tested it and I'm not getting any power past the diode. I could replace the diode but I'm thinking about replacing the entire stator.

I've been looking at parts diagrams and it looks like there are more than one that is similar to mine. It is a "Dual Voltage" type. They all look the same electrically.

The one that looks similar to mine is the 696459.
I am not sure what the "engine" numbers mean in the upper right corner of each stator. They don't seem to match anything I have and I don't see a explanation
My motor is type 2238E1

Can anyone confirm I am looking at the right part #. See pic of my stator.

Also I may be replacing the starter.
I have the 3 5/8" starer housing.
My research came up with: 497596 for the starter.

Also I see some oil leakage past the upper crank seal
I'm looking at 391806S.

Can anyone confirm that I am looking at the right parts to purchase?


Thanks
MarkIMG_3741.jpegIMG_3740.jpeg


#2

StarTech

StarTech

Yes it is a dual circuit Part# 691063 (Superseded to 592831) but replacing the diode is much cheaper the replacing the whole stator at $85. Diode PN 391507 or Oregon 33-414 for the complete pigtail.

Starter is Part# 497596 for 3-5/8 housing.

Flywheel side oil seal is 391806S; unless, you need the bushing too. Then it is Part# 399265 (Superseded to 797673) for the seal and bushing.


#3

B

Bentoolong

StarTech said:
Yes it is a dual circuit Part# 691063 (Superseded to 592831) but replacing the diode is much cheaper the replacing the whole stator at $85. Diode PN 391507 or Oregon 33-414 for the complete pigtail.

Starter is Part# 497596 for 3-5/8 housing.

Flywheel side oil seal is 391806S; unless, you need the bushing too. Then it is Part# 399265 (Superseded to 797673) for the seal and bushing.
Click to expand...
Looks like I'm OK on the numbers then. I thought about getting a diode. How do you attach it back into the conenctor since it looks like the diode is attached directly to the connector. I don't have any shrink tube either so that would add. I think I can scare up an aftermarket stator for around $40.

THe stator other than being grimy doesn't look to bad. No burned coils. I may still try a diode.

Mine was pretty fowled from a seal leak.

Thanks for the help.


#4

B

Bentoolong

How would you test the actual windings to see if just replacing the diode would be OK.
I have a VOM.
What should I see as far as resistance?


#5

StarTech

StarTech

Normally these are tested for output voltage and amperage. I don't the resistance off the top of my head. I can get you that later but right now I am in the middle of an ICE storm and it is not stay yo go to the shop. I do it going very low but not the same sas both meter leads touching each. Since each winding has one end grounded the stator metal frame if you get an open reading there is a break in the windings.

For the diode replacement yes it is crimped the pin of the connector that why I suggest the Oregon assemly where you just under solder the two wires and solder the new assembly in place. As a shop I have the Molex pins, heat shrink, and the ferrel for attaching the diode to the wire. .


#6

B

Bentoolong

StarTech,
I did test for output voltage. I had AC to run the lights but no DC to measure amps with on the diode side.
I may just cut the pigtail off and do some measuring. Now that I know that each winding is grounded to the frame, I can make some initial measurements.

You must be south of me a little to be having and Ice storm. Its around 20 in Michigan right now. I don't think we have been up to 32 in around 2 weeks. We can deal with cold and snow but I feel bad for folks down south right now.

Take your time but I would be curious about those readings. I my just try the diode if I can confirm the rest os OK.

Mark


#7

StarTech

StarTech

I would say I am little bit South by being 3 miles North of the Alabama/Tennessee state line. Expecting up to an inch of ice plus another 1-2 snow/sleet. Really nervous about that Red Maple at the back of my shop. At least the insurance is paid up.


#8

B

Bentoolong

StarTech said:
I would say I am little bit South by being 3 miles North of the Alabama/Tennessee state line. Expecting up to an inch of ice plus another 1-2 snow/sleet. Really nervous about that Red Maple at the back of my shop. At least the insurance is paid up.
Click to expand...
Ice is always tough. We had ice a few years ago and out power was out for around 5 days in a cold snap.

I'll be thinking of you.

I just ordered the pigtail. I'd still be interested in the measurements when you feel like it.

Mark


#9

B

Bentoolong

StarTech,
I've been thinking about your seal/bushing part #. I'm wondering why the upper crank seal is leaking but not the bottom one. Maybe the bushing is bad as well. I just assumed that there was a roller bearing of some sort on both ends of the crank. I'm not clear on the function of the bushing in this case.
Are these parts typically changed as a set or can I get by with just the seal? Maybe the bushing is getting sloppy and that is causing issues for the seal.

Is the bushing a drop in unit? How to remove it?

I don't feel a lot of radial play in the crank in that area. I may put a dial indicator on it just to make sure.
What should I see for movement. I'll assume less is best.

mark


#10

B

bertsmobile1

Unless you have a $ 100 + meter forget about doing resistance measurements .
Cheap HF meters are just not good enough and even then you get different readings depending upon how you make the contacts.
I have tried cheaper stators and all have failed .
The reliable ones from reliable aftermarket suppliers are not much cheaper than genuine down here .
Replacing the diodes is very simple.
Easiest is the complete pigtail including the plug about $ 15 ( Aus ) down here which is what I generally do because it is a 5 minute job & looks professional to the customers.
Although pensioners and other cash strapped customers get the plain diode .


#11

R

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


#12

StarTech

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.


#13

R

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


#14

StarTech

StarTech

Rivets said:
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
Click to expand...
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.


#15

StarTech

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.


#16

B

Bentoolong

StarTech said:
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.
Click to expand...
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.


#17

B

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


#18

StarTech

StarTech

Bentoolong said:
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.
Click to expand...
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.


#19

StarTech

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.


#20

B

Bentoolong

StarTech said:
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.
Click to expand...
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


#21

StarTech

StarTech

Yes Net I agree that it is most likely the diode only is bad as that is what I find most times here; unless, someone reversed the voltage to the stator.. This why I order these diode in quantity of 20 ea at a time and of course the need terminals.


#22

B

bertsmobile1

Just remember that the single diode is a really cheap method of charging the battery .
Anything that impeeds the battery charging like a bad ground connection will cause a lot more current to be blocked by the diode and drastically shorten it's working like.
Similar with bad plugs, a connection that sparks or a bad battery and in particular continually jump starting rather than replacing a bad battery.


#23

StarTech

StarTech

bertsmobile1 said:
Anything that impeeds the battery charging like a bad ground connection will cause a lot more current to be blocked by the diode and drastically shorten it's working like.
Click to expand...
This simply doesn't makes sense as higher the circuit resistance the lower current. Besides I use 1N5408-G diodes which have a 200 amp surge rating; though, I believe Briggs used the 200 PIV version. Just as cheap to use the 1000 PIV version.


#24

B

Bentoolong

Well some good news. I got a new starter installed and that made a huge difference. I bench tested both starters prior to the swap and the new one turned much faster.
I also installed a new diode and that solved the charging issue (13.9V at the battery).

My next question involves the governor. How exactly should this be adjusted? I don't have and issue with anything yet but I haven't done any work with it.
The idle is nice and the part attached the the throttle seems to move through its range rather nicely.
There seems to be a lot of slack in the adjustable screw (with spring). How is that adjusted exactly.
I don't have a reason to believe anything is missing or that it was ever even adjusted. I don't have a tach.
I'm just trying to get things adjusted better and gain some knowledge.
I've looked around at the motor manual (Briggs 42A707) but don't see any instructions regarding adjustment.
The governor arm seems tight.
Educate me please.

Attachments







#25

StarTech

StarTech

The adjustment procedure is on page 8 of section 4 of the 271172 service manual for twin cylinder L-heads.


#26

B

Bentoolong

Thanks, It looks like that long screw adjuster is for the High End RPM adjustment.


#27

B

Bentoolong

I'm finally wrapping up this project.
I installed a new diode and I know have plenty of voltage to charge the battery.

Something confuses me though. I have my DVOM in series in the charging leads at the motor and I show a little around .65A there. The battery is healthy and has round 12.44V without the motor running.

Is the amp reading normal for this type of charging system. I've read the Briggs data sheet on what to expect and how to measure and I was expecting 2-4Amps. Maybe if the battery was low it would change. I would expect that to be the case with a regulated system but not one with just a diode.

Am I OK at the readings I measured?
A better way to test?


#28

B

Born2Mow

>> Diodes are nothing but one-way gates for electricity. So with a battery powered Ohm meter you should get a reading with the probes on the input and output leads. When you reverse the position of the 2 probes there should be no reading. The diode will need to be unplugged from the other circuitry to make this test.

If you have a rectifier and not a simple diode, that's nothing more than 4 diodes arranged in a pattern. You can bench test all 4 diodes the same way. If one diode goes bad, then your charge rate is immediately cut by one half. In other words, if the battery is supposed to receive 2.2A charge current, but you only get 1.1A, then that's a dead giveaway.

>> A lot of simple machines (like generators and stators) are reversible. When you rotate a generator, you get power out. But, if you put power into a generator it will rotate like a motor. Same for stators. If you move a magnet near a stator you get power out. But, if you put low voltage into a stator, then the coils turn into simple electro-magnets and will attract small steel objects.

The second simple test for stators is to take your Ohm meter and connect between the steel body and all the output leads. There should be zero connectivity. This is to make sure the coils are not "shorted" to the steel frame.

That's about the only 2 failure modes of a stator, and you can complete those tests easily within 5 minutes.

But if spending $85 is necessary for your well-being, then there's always my retirement fund !! :ROFLMAO:


#29

B

Bentoolong

Born2Mow said:
>> Diodes are nothing but one-way gates for electricity. So with a battery powered Ohm meter you should get a reading with the probes on the input and output leads. When you reverse the position of the 2 probes there should be no reading. The diode will need to be unplugged from the other circuitry to make this test.

If you have a rectifier and not a simple diode, that's nothing more than 4 diodes arranged in a pattern. You can bench test all 4 diodes the same way. If one diode goes bad, then your charge rate is immediately cut by one half. In other words, if the battery is supposed to receive 2.2A charge current, but you only get 1.1A, then that's a dead giveaway.

>> A lot of simple machines (like generators and stators) are reversible. When you rotate a generator, you get power out. But, if you put power into a generator it will rotate like a motor. Same for stators. If you move a magnet near a stator you get power out. But, if you put low voltage into a stator, then the coils turn into simple electro-magnets and will attract small steel objects.

The second simple test for stators is to take your Ohm meter and connect between the steel body and all the output leads. There should be zero connectivity. This is to make sure the coils are not "shorted" to the steel frame.

That's about the only 2 failure modes of a stator, and you can complete those tests easily within 5 minutes.

But if spending $85 is necessary for your well-being, then there's always my retirement fund !! :ROFLMAO:
Click to expand...
I'm not sure this answers my question. I'm looking for a way to insure that the charging system is working properly.
The B&S method is to measure amps in series between the diode and the battery. My reading seems low. I have a simple diode that measures adequate voltage now that it has been replaced.


#30

StarTech

StarTech

Well if he actually fully knew what he was posting about would help. In your setup the diode is use as a half wave rectifier (one pulsed system). I hate see what he would do if he ran into a six-phase full-wave bridge rectifier circuit that has 12 diodes (12 pulsed system). Be it a star or wye-delta fed rectifier system

But as your setup the amps will lower at idle and near the 2-4 amps @ 3600 rpms. As long as you have a positive current and a charge voltage above the standing battery voltage you should be find.


#31

B

Bentoolong

The issue I originally stated was that I am seeing around .65A in the circuit. That seems low.

I see 12V to ground at the connector to the battery so I know the connection is good and the fuse hasn't popped.

I'm still not clear on what I am seeing on my meter at .65A. Is that OK?


#32

T

Telesis

Bentoolong, you are correct in saying if your battery charge was lower, you'd see a higher current. Briggs puts a couple asterisks next to the spec of 2-4A for this dual circuit system(and others) and states that the current is dependent on battery voltage and "if the battery voltage is at it's maximum value, the amperage measured will be less that shown." The simplest test is what StarTech mentioned. Measure the battery voltage with it off, and when it's running at high speed(3600rpm). If the battery voltage is higher while running then it's a good bet it's charging!


#33

T

Telesis

We happen to have been typing at approximately the same time. The short answer is Yes 0.65A is OK! Just means you have nicely charged battery!


#34

B

Bentoolong

Thanks folks,
The last few posts helped. I measured at the battery at idle. 12.5V. Revved up to top end and it was 13V. Fixed and done. All I need now is grass. Got up to 45 in Michigan today.

Ben Toolong


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