1928 Ford Powerhouse Generator and cut out questions

[Shade Tree Mechanic]

Greetings all,

This is my first post to this group and I am hoping someone can help. I recently purchased a nice 28 Phaeton that wasn't running. I rebuilt a T over Covid, and helped a few friends with A's over the years, but this is my first Model A.

While troubleshooting - the first thing I found was that the new battery the previous owner put in had the polarity reversed (i.e. Neg ground) along with the coil polarity (Red to Neg -) . The Red wire to the key was also badly frayed, and shorting out - and the timing, points and plugs were also significantly off. After some tinkering I was able to eventually get her running.

Going down the checklist, I noticed the ammeter never showed a positive charge. (It showed Negative when lights on) Nevertheless, I'm assuming at least the Ammeter is ok.

When I returned after a short test drive the battery was down from 100% to ~90% on my charger. At that point I'm doubting the generator -

As my first test I ran it to a hi rpm, and tried disconnecting the battery Neg. post... She died instantly with a couple loud bangs (D@#$%^ OOPS!) Thankfully, after reconnecting the post, she started up fine -

In most car's I've tinkered on, when disconnecting a Battey the generator / Alternator and voltage regulator would cut in and keep the ignition running... but I'm not sure about A's. Am I way off with that test?

The next troubleshooting step was checking the output of the generator at both low and hi rpm. In both cases the voltage never changed, and it stayed at a steady 6.1vdc. (Same as the battery)

After that, I pulled the generator (Which is a period accurate 28 model A Ford Ar power house generator)... I opened it up and all looked 'ok' so I removed the cutout (Voltage regulator) and spun the generator up with a drill. Thankfully, it showed a steady climb in voltage up to 7.5 vdc... Les Andrew's book say's 7.2 is good, so, I'm thinking the generator is also ok...

That leaves the cut out switch - I opened that up and I was a bit surprised to see what looks like a DIODE instead of coils and points...

So - questions -

Any way to confirm this is a blown diode?
Can reversing battery polarity short out a cut out diode?
Any recommendations on where to get a replacement cut out for a power House Generator?

Thanks in advance for any and all your help

Marty

[Jim/GA]

You determine if a diode is good or bad with an ohmmeter.

On a good diode, you will get continuity one way and not the other way.

On a bad diode, you might get continuity with a meter in both directions -- diode shorted out inside -- or (more commonly) you will get no continuity in either direction -- diode burned up.

[Shade Tree Mechanic]

Thanks - I appreciate the response and agree 100%

After sending my posit I did learn something new though -

It turns out there are two different types of diodes for a model A...

One for POSITIVE GROUND and one for NEGATIVE GROUND

(Per Snyder's)

DIODE ONLY / Negative Ground Part # T-5055-DIO
or
COMPLETE CUTOUT / Negative Ground Part # T-5055-F

and

DIODE ONLY / Positive Ground Part # A-10155-DIO
or
COMPLETE CUT OUT / Positive Ground Part # A-10505-SS


I now believe the car was wired and running with Negative Ground all along. I switched it to Positive Ground, thinking it was backwards, and defeated the diode... (Pilot error again!)...

I went ahead and ordered the POSITIVE GROUND Cut Out... and I'll update this post ASAP

[Bruce of MN]

Stock Model A’s don't have voltage regulators. The generator output is adjusted by varying the third brush position. I assume that applies to the powerhouse.

[Joe K]

Originally Posted by Jim/GA

You confirm a bad diode with an ohmmeter. You will get continuity one way and not the other way.

You said that almost right. You can confirm a good diode with an ohmmeter. You will get continuity one way and not the other way.

Not to critique.

Joe K

[updraught]

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If the generator is working and you disconnect the battery it will dump the power into the wiring. If the lights are on, you can test this as they will instantly blow.

[Jim/GA]

Originally Posted by Joe K

You said that almost right. You can confirm a good diode with an ohmmeter. You will get continuity one way and not the other way.

Not to critique.

Joe K

You are correct. I am going to go back and edit it for clarity.

Thanks.

[jrelliott]

If the A was changed to Negative ground, and the generator polarized that way, then continue to run the A that way. It will run just fine. On disconnecting the load from the generator you can damage the generator. The Powerhouse generator is much better than the later models and the roller bearings bearings at both ends can be replaced easily. On the Powerhouse on my A, when I replaced the bearings, there was still grease in them. Just wanted to have everything new. I run 12V negative ground with the Powerhouse and a cutout.

[nkaminar]

The best way to determine if you generator is working is with a voltmeter, not by disconnecting the generator. If you disconnect the generator it can be damaged. For a 6 volt system the charging voltage (fast idle) should be about 7 volts. The voltage will go up as the battery recovers from starting the engine.

The generator can be polarized by removing the fan belt and connecting a wire from starter switch terminal to the generator output terminal (not cutout terminal).

Adjust the third brush to keep the battery charged but not overcharged.

With the diode backwards the ammeter will show discharge when you hook up the wiring and the motor is not running. Also bad for generator.

[Shade Tree Mechanic]

Thank you all for the good advice -

[Shade Tree Mechanic]

Thanks for your advice on polarizing the generator!
To Nkaminar - For clarification - you had said...

... "The generator can be polarized by removing the fan belt and connecting a wire from starter switch terminal to the generator output terminal (not cutout terminal)"

Do you mean the starter terminal post - which is connected to the NEGATIVE side of the battery?

If that's right, then I would ground the generator housing to the engine - (Positive GND) and then jumper a wire from the Starter Terminal (Negative) to the Generator Output Terminal ... not the cutout.

I would then put the new POSITIVE GROUND cutout in last...

Since the generator is now out of the car- could I also use jumper cables to put the positive lead on the generator housing and then connect the negative wire to the generator output? - that should also turn the generator into an electric motor and the shaft should turn - yes?
...
as for Adjust the third brush... so far, I haven't found anything showing how to do that with the power house generator - but I am going to hope it doesn't need to be adjusted just yet...

[nkaminar]

"Do you mean the starter terminal post - which is connected to the NEGATIVE side of the battery?"

Yes.


"If that's right, then I would ground the generator housing to the engine - (Positive GND) and then jumper a wire from the Starter Terminal (Negative) to the Generator Output Terminal ... not the cutout. "

Yes. I was assuming that the generator was still in the car.


"Since the generator is now out of the car- could I also use jumper cables to put the positive lead on the generator housing and then connect the negative wire to the generator output? - that should also turn the generator into an electric motor and the shaft should turn - yes?"

Yes. All this can be done on the bench with a battery or jumper cables. Positive to generator case and negative to generator terminal. The generator will motor slowly.



What this does is polarize the field windings. This little bit of magnetism snowballs in the generator when the engine is revved up to produce the voltage to charge the battery.

[Shade Tree Mechanic]

GREAT! Thank you!

I'll update all after I get the new Positive Ground Cutout and things back
together!

[rotorwrench]

Polarizing the generators through the armature isn't the best way. The 3rd brush wire, when isolated from the armature, is the best connect point to momentarily polarize the pole shoes using the field coils. Power (negative) to the field wire and ground (positive) to the generator case will let the coils do all the work. It only takes a few momentary zaps through the coils to polarize (magnetize) the shoes.

Most model A diode cut out replacements are made for Positive ground but both were available since the Model T set ups were Negative ground in some cases. Always make sure the product you are after has the polarity you need.

You are fortunate to have a Powerhouse generator in good shape. The big brush ring is made from bakelite so they like to crack and crumble. They are very good units if everything is in good shape. There were the five brush types and three brush types but all are good. They put out more amps than the cylinder shaped generators of the Autolite design. They are also easier to adjust the third brush since the whole ring is exposed when the cap comes off the back. Changing or repairing the fields are more complicated so a person needs to know how they are arranged to get them to work properly.

[Shade Tree Mechanic]

greetings all - ok to close this case -

Thanks again for the help and information. I polarized the generator for Positive Ground, and put in a new Positive Ground Diode in. Its now all working well. DC Output is good, and the ammeter is showing good charging current.

Moving on to rebuilding the carb, and some distributor clean up.

Have a good weekend !