Emerson 73646-AK Lack Of Variation Between Speeds – Is This Normal?

[Fred Ames]

Hello everyone.  I’m new to this forum but have enjoyed looking at people’s questions and seeing the wealth of knowledge in the replies of forum members who have “been there” and “seen this before”.

Around 40 years ago I inherited a great running Emerson 77646-AD pedestal (1938) from my Grandfather. He used it in his clothing store in Bellingham, Washington. As summer is coming, I decided to look for a table model of the same vintage and bought a 73646-AK from 1937. It’s in great shape except that there is hardly any change between the three speeds. I cleaned the switch and did resistance checks on the speed coil and stator and they are similar to the values in wiring diagrams I’ve found on this forum (old forum). I replaced the original 1.75  220V capacitor with a 1.5 450V and this definitely improved the variation between low, med and high, but the difference in speeds is still not very much. I’m now wondering if this might be the norm on these early split phase capacitor motors as the speed variation on the pedestal fan are similar.

I would love to hear some thoughts on whether it’s normal for this fan to have a rather high “low speed” and not a lot of variation between speeds.    Thanks!!
 

[Lane Shirey]

Use a kill a watt meter to measure running current on all 3 speeds. There should be some difference, with high speed being the highest amp rating. 

[Fred Ames]

Thanks for the reply Lane; I just happen to have a Kill-A-Watt meter.  On both low and medium speeds I read .31 and on high .33 amps.  I also checked the watts and between each speed the wattage went up by about .6 watts.  Did the same on the pedestal fan (still has original capacitor) and the amp draw actually went down a bit on high speed. The wattage though did go up on each speed as you might expect.

[Fred Ames]

Some of you might get a kick out of what I did next...

I mentioned that the variation between speeds was similar between my two fans… Not having a way to measure motor RPM,  I did a geeky thing to compare…  I downloaded a Frequency Generator App on my phone and with my musical ear, matched up the frequency to the tone of the fans on low, medium and high:

                                                73646-AK Table Top               77646-AD Pedestal

Low – Med difference                        4hz                                         6hz
Med – High difference                       6hz                                          9hz

As you can see, the Pedestal fan has more variation in between it’s speeds than the Table Top, but not by much.  It might be interesting on the Pedestal to see if this changes should I replace it’s original capacitor.   Is this one of the geekiest post you’ve ever seen 😊
 

[Stan Adams]

The 73646-AK models I have owned do not have a lot of speed differences on 125 volts which is normal in my area. If I lower the voltage to 115, I get a better variation. The increased voltage from when that fan was produced in the early 30s has a habit of saturating the choke.

[Fred Ames]

Thanks Stan !  It's good to hear from someone that's had a similar experience with the 73646-AK.  I'll dig out an old variac and see how the fan runs on 115V... Just curious.