Original BP M Head 110/220v Troubleshooting

[Shiseiji]

No joy with the cap
No direct shorts in the windings. 1.1 and .5 Ohms resistance.

I tried 189 - 227; 216- 259; 220-324 and a 270 - 324 caps. I managed to plug it in the 2nd to the last time without the cap installed. That was informative as the noise from the motor was the same as with the first 3 caps.

The last test was with the 270 - 324 and the motor started to revolve but with very loud complaint and probably less than 60 RPM with 60 being generous.

 

[sdelivery]

Shoot for 460-550 mfd

 

[Ulma Doctor]

Added capacitance is not going to solve this problem.
The problem ( edit; most likely )resides in the windings or the centrifugal start switch

 

[Geswearf]

Motors are not rocket science. That said, I admit I don't know a whole lot about them despite being a retired electrician. Its the old story of what was your specialty...and I did virtually no motor/control work as a primarily residential electrician. I've always said, when all else fails, follow the directions, with a corollary, to seek expert help when needed. Take the motor to a motor shop and ask them for pointers troubleshooting it. You have done a lot already, and if you talk to the guys there, they will likely give you lots of good information. It should take a knowledgeable guy only a couple of minutes to figure out what is wrong. You can decide what to do once you have this information.

You can also find good info on the web, but it will take reading several sources to learn enough to separate the good from the bad. This is different than books, since they were expensive to publish most are pretty good. Motor manufacturers also publish a lot of good information. I don't know if the start windings on your motor are separate from the run windings or if they are simply switched to add to the run windings. Testing should be pretty simple and straightforward.

 

[Shiseiji]

Motors are not rocket science.

Motor manufacturers also publish a lot of good information. I don't know if the start windings on your motor are separate from the run windings or if they are simply switched to add to the run windings. Testing should be pretty simple and straightforward.

Help and suggestions are always appreciated. Lets review where we are at. It's been decades, but I earned my FAA General and Powerplant certificates. Motor troubleshooting, including cleaning, turning down, and trimming DC motor armature mica was in the FAA required curriculum. That said, I'm never shy about asking for others opinions, and I may have run out of options except to go where others have better testing options.

There is a history of the Master Electrical Co. Dayton OH USA posted to Vintage Machinery. The plant where the motor was built closed in 1961.

Two separate windings, hence the two different resistance readings. An Ohm reading = continuity and "probably" no break in the windings though it could be at the very end and resistance would be a false indication of no trouble.

No measurement/no path between the windings and the case = no failed insulation to validate the above test.

Centrifugal start switch points are clean, no resistance in the closed/start position. The carrier plate moves smoothly into the "started" position with zero resistance or evidence of wear. Snaps back into the start position when released.

Things to re-check. The wiring between the cap and the starting winding. The fact that the motor did start to rotate with the higher capacitance "could" indicate a break in the wire/high resistance and the kick being insufficient to get the motor up to a sustainable RPM and fast enough for the centrifugal start switch to disengage. Easy enough to test with a jumper wire.

Anitional ideas & troubleshooting tips always appriciated.

Best I can find, there is one shop left in Olympia, WA ~ an hour away. I thought I would surly find several around the Port of Tacoma, ~ :90 away on a good day, 2:30 on a bad, but apparently there just isn't enough business anymore. All the others are further north around Seattle. I'm on the local informal metal group email list, I'll be checking with them to see if there are any shops I missed.

Thanks again everyone, it may not be a quick report back, but I will close this thread out when I learn anything new.

 

[markba633csi]

It should have started up with any of the caps you tried- something else going on- To review:
The main winding and the start leg should be in parallel. The start leg is comprised of the start winding, the centrifugal switch and the capacitor
all in series. The 3 series components can be in any order.

If you have a multimeter, you can test the start leg by itself with the meter on ohms. This is best done with an old fashioned needle type
meter (Radio Shack cheapo or fancy Simpson- doesn't matter) A digital meter might be usable but the flashing digits can be hard to interpret.
Separate the start leg from the main winding and check it with the ohmmeter. You should see a reading which goes quickly to zero then rises toward infinity. Reverse the test leads and you should see this again. You should see this each time you swap the leads. You are essentially
seeing the cap charging/discharging thru the start winding and the start switch.

One winding could be shorted internally. In that case repair is unlikely. Time for a new motor.
The start winding usually has a somewhat higher resistance than the main winding(s). (modern motors usually have 3 windings: 2 main and 1 start)

 

[Shiseiji]

Dropped the motor off at a shop today. More to follow.