US Member - 1 Year
Topics: 25July 18, 2019 at 4:36 am #179112
How does one tell the difference? is there a test? markings on the regulator? or just have to dig through part numbers and specs?July 18, 2019 at 8:46 am #179116
Not knowinig what you have, all I can do is explain how they control the field circuit (and thus voltage).
A type A generator starts producing a voltage in the armature windings as it starts to spin (remember, it retains some residual magnetism in the fields to get things started). That voltage in the armature is fed to the battery if high enough to close the cut-out relay contacts. At the same time, it is also fed to one end of the field coil windings. It passes through the field windings, and goes out the field terminal on the gen. From there, it goes to the field terminal on the regulator. The voltage regulator contacts are closed if calling for gen output, so the field circuit is grounded, completing the field circuit from armature to ground, and a current flows through the field windings. The current flowing through the field windings causes them to become electro-magnets, adding to the residual magnetism already there. The added magnetism causes more voltage to be produced in the armature, till eventually it is high enough to close the cut-out relay and go on to the battery. And so it goes till the voltage reaches it’s set limit, then the voltage regulator contacts open, interrupting the field ground and current and charging more or less stops. Actually, the contacts vibrate, causing a rapid connect/disconnect to ground.
OK, if you waded through all that, the important thing to absorb is the voltage regulator GROUNDS the field circuit when charging is called for (external ground).
Without going through the whole scenario, a type B generator is different in that the inner end of the field coil is grounded to the case instead of going to the armature.. The type B voltage regulator applies battery voltage to the field terminal on the gen to complete the circuit to it’s internal ground, increasing the field magnetism and causing a voltage to be produced in the armature and on to the battery. And so it goes.
Summing up, Type A regulator GROUNDS the field terminal, Type B regulator APPLIES VOLTAGE to the field terminal.
Got it????July 18, 2019 at 9:19 am #179117
I might as well add something to all this discussion. The OMC/Prestolite regulator looks just like a hundred car regulators. But the OMC version limits generator output to 10 Amps. I don’t know of any car charging systems that only produce 10 Amps. You might be tempted it just use a car regulator and get 30 Amps or more. Trouble is, that will burn up the generator armature.July 18, 2019 at 9:30 am #179118
One last thing, then I’ll shut up. For years, OMC put the regulator in a junction box in the boat. Then they eliminated the junction box (good riddance) and put the regulator under the motor hood and changed the part number. Supposedly, the under-hood version is sealed against fuel vapors which might be ignited by the vibrating contacts inside. Remember, it is right under the carburetor. Word from here is use the correct part number for under-hood mounting.
US Member - 1 Year
Topics: 25July 18, 2019 at 9:10 pm #179165
WOW that is allot to wrap my head around, but I think I kinda got it. I heard about that regulator mounting change but never seen one hands on. I did think of the possible explosions hazard that it might create and kinda puckered a bit and cringed. [I worry about the starter solenoid that I have mounted under the cowl. but I guess there are other ignition sources [points, starter brushes ] that could also cause that problem . I guess I will have start by getting the meter out and run some tests to see if I can decipher which generator I have “a” or “b” generator. maybe I can find a schematic of those systems somewhere . thanks again for all the input
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