Cut out problem on 30?

[old31]

If an amp meter goes from zero to negative when the lights turned on, and when the brakes are applied, but never shows a positive could that be the cut out?

I increased the third arm but that did not increase any activity on the plus side of the meter.

[ryanheacox]

Could be, give it a good tap and see if it starts charging.

[katy]

Check system voltage before starting the engine, w/engine running at a fast idle recheck system voltage, it should be higher.

[Badpuppy]

Indicates generator not charging, probably open cutout. Maybe bad brushes or open wire inside.

[Patrick L.]

Is the generator charging ? Check voltage at genny output lead. Has any work been done recently ? It may need polarizing. Of course, it could be the cut-out contact is not closing and needs some work. Do you know if its an original style cut-out or a repro. The repros are pretty much junk.

[old31]

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The gen never shows a charge. Not sure if work was recently done, I am new to the car.
Not sure if repro or original, will take it apart next week and take a look and let you know what I find.

[Patrick L.]

Well, loosen the belt and see if the generator motors. Just put power to the genie and it should spin slowly. If it does then there is a 99% chance its good. If it doesn't motor there is something wrong with it.

[eagle]

Number one, don't take anything apart until you find out what's wrong. Put a good quality voltmeter on the battery before starting, and then when running at a high idle. Then check the voltage on each side of the cutout. Also verify that you have a cutout. The voltage regulators or diode cutouts look the same from he outside, VR is very desirable and if you short across it you will ruin it.

[old31]

Originally Posted by Patrick L.

Well, loosen the belt and see if the generator motors. Just put power to the genie and it should spin slowly. If it does then there is a 99% chance its good. If it doesn't motor there is something wrong with it.

So, with the belt off, then what do you do with the wires to power it up?

[Patrick L.]

Originally Posted by old31

So, with the belt off, then what do you do with the wires to power it up?

Just take a jumper from power to the generator output terminal. The generator should spin slowly [ called motoring} If it does chances are the generator is good. If you remove other wires, which I think is your question, just make sure they don't contact [ground/short] to anything.

As mentioned, try to figure out which cut-out you have. Jumping across the 2 cut-out terminals on an original cutout will polarize the generator but can destroy some aftermarkets depending on what is inside them.

[Kurt in NJ]

To motor generator connect battery power to generator post
a powerhouse generator motors at 2.5-3.0 amps
the later long generator motors at 4.75-5,0 amps, 350-400 rpm
with the 3 brush generator the battery is the voltage regulator, if the cutout fails to make connection the generator voltage can go over 40 volts, the smoke can come out, the armature can overheat and the solder can melt off the commutator.(this can also happen when the fuse on the starter blows)
if a generator passes the "motoring test" most likely it works,though sometimes not fully, there can still be problems preventing full output ,usually armature related

[rotorwrench]

If the generator has output, a person can tell using a 6-volt test light or a volt meter connected to the generator output terminal. I would disconnect the lead from the cut out to the terminal box to do the check but only with a real cut out or a diode. This way a person can see if the cut out closes or diode functions while the engine is running. The voltage generated using residual magnetism in the generator poles is enough to function the real cut out and it should be just a bit higher than battery voltage to do that. If it can't generate enough power to close the cut out then the generator is at fault. Normally, polarizing recharges the field pole shoe magnetic force or gauss enough to generate the voltage needed and at the correct magnetic polarity to match the battery connections. Lack of gauss in the pole shoes comes from long periods of inactivity or new pole shoes that haven't been recharged yet. If it was working and then stopped working then the gauss should still be there.

If you have a Fun Projects voltage regulator on there then all you can do is check the output voltage. The battery can not be disconnected from the system in any way or it will kill the regulator.

If you have a diode, it can be checked with a multi-meter set on diode test. Connect the leads one way and then the other. It should give a beep if it passes current one way but it shouldn't beep when passed the other direction with leads reversed. If it doesn't work either way then it's bad. An ohms meter with a sweep meter movement can also be used but it reacts a bit differently (no beep). It will have meter movement one way but not the other. If you use the voltmeter to test, power has to be applied to the other end of the diode. It should pass voltage from the generator side to the battery side but not the other way around. If it passed no voltage or voltage both ways then it's bad.