webster testing

[Kevin Weis]

What is the best or correct way to test a Webster mag with a volt meter? Do you just spin the shaft for a direct reading and how fast would it have to rotate for an accurate reading? What should the reading be? The Webster I got is a model AMM that was on a Rock Island/Alamo 1 1/2 hp. Any thoughts appreciated. Thanks - Kevin

[Ken Majeski]

Acording to what I have here the Webster MM should put out a minimum of 13 volts and 60 Cycles AC at 599 RPM... You can spin it with a variable speed electric drill after you remove the springs.....

[Kevin Weis]

Thanks Ken, I'll get a volt meter shortly and see what I come up with. Thanks again - Kevin

[Kevin Weis]

Ken, at approximately 600 rpm I'm getting about 6 volts more or less. I take it this is not good as you say it should be around 13 volts. Is this indicative of the magnet needing recharging? When I first got it the armature was rubbing the poles due to worn plate bearings. Put new plate bearings on dosen't rub anymore but could now the gap between the armature and poles be too great and hence the voltage drop?. Thanks for any responses - Kevin

[Ken Majeski]

Yes, Magnets could be weak, There could be a buildup of Rust, Dirt, ect where the magnets contact the pole pieces.... There could be a shorted turn or two in the coils.... Or like you say the armature is worn causing too much clearance.

Also if the magnets have been charged Backwards they never seem to be quite the same....

Some say Never to remove the magnets... BUT... I have always removed them to clean and Charge... Then put a keeper on them before you remove them from the charger and when you slide them on the mag just push them down and push the keeper off the rounded end.

If someone has replaced the coils with the wrong ones they could have less turn turns which could cause low voltage.

I remember we had a 1 HP Ingeco once.... Had a Small Webster with only one Little magnet.... Never did get the Dam Thing to work... Does your Mag have one magnet or two...????

[Kevin Weis]

Ken, It has two magnets being an 'MM'. I saw from similar threads to check the ohm between the ground and primary wire and that it should read between 8 and 12 ohms. Mine read a little over 9 which I take is acceptable. With the points closed on the igniter it read 0 which I take is good. I should say before I go too much further that I sent the whole thing off to Mark's Magneto for the once over today for proper testing and recharging of magnets or whatever it needs. The consensus from the other threads was to leave re-charging of magnets to a professional which I have done. Appreciate all the advise and information as I'm now fairly confident on what repairs are likely needed. Thanks, Kevin