American Bosch AB33

Good morning, I’ll try this again, I am a retired electrician and Tinkerer, living in Florida, USA, currently working on a Bosch AB33 mag which was mounted on a FM Z engine which was submerged in seawater, I currently have it all disassembled and am about to install a new cap, anything I should consider, testing etc before assembly, some else has taken this apart previously.
Geo

Morning Geo and a Happy New Year.
We have family in Clearwater, Tampa and Fort Myers but it's been a while since we crossed the pond.

My first port of call would be to check the resistance of HT and LT windings. I'm guessing 4K - 5k on HT side and very low ohms on LT side. If HT shows open circuit then you are probable looking at a re-wind.

Have send two Bosch AB33 'manuals' - check your email.

Thanks,I did receive the downloads, how do I determine the Hi voltage and low voltage windings ,currently I have 2 leads coming out from the armature, not sure how to post pics on this site.
Geo

geochurchi wrote:Thanks,I did receive the downloads, how do I determine the Hi voltage and low voltage windings ,currently I have 2 leads coming out from the armature, not sure how to post pics on this site.
Geo

Not familiar with this magneto but generally speaking you can check HT side by connecting meter between slip ring and earth (ground). Just make sure you have a nice shiny clean area on body. I'm assuming the mag is on the bench so no other electrical paths?

Actually, when I think about it, it doesn't matter which lead you try first - one winding should be around 4k-5k and the other should be very low ohms - probably show as short circuit on a digital meter.  Both docs I sent have circuit diagrams.

As regards posting pictures. see:  https://ukengineforum.forumotion.com/t9665-how-to-upload-images
It seems a bit of a faff but follow instructions carefully and you will get there.

Thanks, and I will give the pics another shot.

https://i.servimg.com/u/f82/20/53/92/25/img_4113.jpg Hi, don’t know if this will work but I am trying to figure out if there is something missing under the arm , currently there is a well worn thin brass washer, also any thoughts as to what I may use for the oil wicks ?

Hi All, any idea what the points gap should be, I don’t have the Bosch wrench.

According to some general Bosch magneto info I have the gap should be 1/64" i.e 15 thou or 0.4mm

OK, Thanks

Just saw a spec on points gap, set points to a thickness of a thin dime, seems pretty precise.

Sounds like a well worn dime!  
According to that well known online encyclopedia a new one is 53 thou thick.

Good morning, still no spark, everything seems in order, will increasing the magnets have any effect on the performance?
Thanks

Can you post the resistance readings you got please?

I will at some point, that will mean disassembling it again, as I remember they were close to what you suggested, 4-5 K , and nearly shorted, if I did it right measuring each lead to ground, see pics of how I have the Cap installed I did not use any exopy etc.

Thanks

Here’s another link that I found interesting.
https://occhiolungo.wordpress.com/2010/02/24/how-to-magneto/

No worries. If the readings were good we will have to think of something else.

Thanks for posting the link.

Hi,

I presume that you tried the test procedures in the manual I sent. My next suggestion is as follows:

Place a fly lead from HT to a point near the body with a spark plug sized gap.
Slip a piece of thin card between the points to simulate points opening.
Attached a couple of fly leads to a small (9v?) battery and hold against a shiny spot on the body (earth) - polarity unimportant.
Then dab the other lead against one side of the breaker points. That should cause a brief current to flow in LT coil and hopefully you may see a spark.

If that fails I think you need to look for short circuit, failed or missing insulation, break a connecting wire etc.
Best of luck.

Good morning, I assume a fly lead would be a “jumper wire “ anyway where do I access the HT, isn’t that the spark plug lead, could I just use that lead near ground or even just lie the plug on a ground and see if I get a spark there ?
Maybe a one line Dia would help explain if I am incorrect.

Cheers!

Exactly as you say - apologies for any confusion.

"fly lead would be a jumper wire “  -  two nations divided by a common language.

Greetings, I did the test both with battery and using the trip arm, I also used an inline spark plug tester , results: plug sparked when I used the battery as well as the spark plug tester , tester sparks everytime that I use the trip arm and very bright, spark not really strong when using the battery , thinking the plug could be the issue although it’s hasn’t been used much ,it’s an Autolite 3095, could magnets be a concern ?

Sounds like you have a spark. If it's nice a bright one then magnets should ok.

As regards spark plug - looks like there are plenty of alternatives  
https://www.sparkplug-crossreference.com/convert/AUTOLITE/3095

Hi, spark plug not that bright when using the trip arm , could adding more magnets help?

Hi, any thoughts on insulating the leads from the capacitor?
Thanks

Hi All, can I assume that the magnets on my magneto are permanent magnets, still have not found a good means of recharging them although I do get a weak spark when I stack some additional magnets, so that’s a good sign, one other question, the magnets are flat about 2”x 4” , I assume that the ends are the N/S poles.
Geo

Have emailed Lucas manual which may help.