CJ750 toolbox
Cajun Mike on CJ electrics

These two regulator types are commonly found on 6V CJs.

This is how a regulator works, in this case, on a 6V system.

With the engine stopped (and the generator not turning) the regulator will be in the state above. R-1 is the battery cut-off relay. The contacts are open when there is no generator output. They remain open until 6.5V output is seen from the armature (A) terminal. When that occurs they close and connect the battery to the generator. This relay is used to isolate the battery from the generator when the engine is not running so that the generator circuit will not drain the battery.

R-2 is the field control relay (F) terminal. It is closed providing a ground for the generator field. Only with the generator field terminal grounded can the generator have any real output.

With the engine running, the regulator will go to this state. R-1 is now closed because the generator voltage is above 6.5 volts. Generator output is now charging the battery. R-1 turns off the generator light on the headlight assembly when it closes. R-2 is also closed, grounding the generator field allowing output as long as the voltage is under 7.5V and current (amperage) is not too high for the battery.

If the amperage or voltage get too high, R-2 opens and there is no generator output.

To troubleshoot a no-voltage problem, try this:

With the engine stopped, meter the F terminal. It should have a very low resistance to ground. If so, measure for 6.5-7.5 volts on the A terminal with the engine running. If the F terminal is grounded and there is no generator output, the problem is inside the generator. If you don't get a ground on the F terminal (or high resistance) open the box to see if R-2 is closed. If so, you may want to file the contact points and see if you get a good ground at the F terminal.

Chinese components use different nomenclature to identify the FIELD, ARMATURE and BATTERY terminals. The picture above explains what's what.

See Mike's page on 6V generators for additional useful information.

Additional, important information from Gerald Gardebled

On certain generators the MZF-12 designation does not mean 12V.

6V generators mainly came with the following numbers:

MEF-11 & MZF-11 which are used with MTY-1 (mechanical) & MTY-45 (solid state) regulators.

MZF-12 & MZF-12A which are used with MTY-2 and MTY-45 (both solid state) regulators.

MZF-11 & MEF-11 are both 6.5V 7A generators. MZF-12 is a 6.5V 10 or 12A unit and MZF-12A is 7V 10A

The MZF-12 & MZF-12A generators were made to improve charging.