Model A

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Powerhouse Generator Regulation Considerations

The following pic and description regarding voltage regulation on the powerhouse generator was recently posted on by Tom Wesenberg. Thanks for his permission to post it here, too!


All powerhouse brush holders should have the ground brush posts soldered to the steel frame of the brush holder. After 80 years some of these posts don't always make a good connection to the steel brush frame.

Use an Exacto knife to scape clean the area to be soldered at the base of the post and the adjacent steel frame.

After you solder the ground posts to the metal mount, if you still don't have output from the generator, make sure the cutout is working and properly adjusted.

Cutout Function:

Remove the cutout and connect the 6 volt car battery positive to the cutout case and touch the negative to the terminal which connects to the generator stud. You should hear and feel the cutout contacts closing. If not, disconnect the battery and connect an ohm meter to these same connections and check the ohms.

An original cutout should read about 50 ohms, and a repro cutout may show about 30 ohms. If you get a good ohm reading, but the cutout doesn't close the contacts at 6 volts then you'll have to remove the spot welded cover and repair or adjust the cutout.

The contact points should have an air gap of about 0.020 inch, and when they are closed you MUST have an air space above the armature core. Often times there will be small metal grit on top of the iron core which can keep the points from closing. Compressed air will blow these away.

If the ohm check showed an OPEN winding, check the fine wire soldered to the cutout base. I have found several of these have come loose. You need a good size soldering iron or gun to get the base hot enough to make a good solder connection.

Electronic Voltage Regulator:

Proper closing voltage for the cutout is especially important when using an electronic voltage regulator, as the EVR keeps the generator output voltage regulated to 8 volts or less open circuit voltage. So if the cutout doesn't close until it has 8.2 volts the contacts will never close. Adjust the cutout to close at 6 volts and it will work fine.

A generator WITHOUT an EVR can reach output of over 30 volts with an open charging circuit. The charging circuit is an open circuit until the cutout contacts close and connect the generator output to the battery. So, even if the cutout is adjusted to close at 15 volts the high generator voltage will close the cutout contacts, even though this is too high a setting.

If you have a poor connection at the terminal box, amp guage, or battery and ground connections this will make the unregulated generator put out high voltage, which can burn out the lights, coil, and generator.

After installing the EVR (and making sure it was installed correctly), and you still see no output, jump a wire across the 2 cutout terminals to bypass the cutout. If you now show output you know the cutout needs repair or adjustment.

Don't expect to see the same high amp reading after installing the voltage regulator that you saw with the stock unregulated generator. With an EVR and a good battery the amp guage will usually show between 5 and 10 amps right after starting the engine, then within a few minutes the charge should taper back to 1 or 2 amps.

Tom Wesenberg
April 22, 2009

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