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 Post subject: Re: Questions regarding Electrola motors
PostPosted: Mon Jun 25, 2018 8:49 pm 
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Victor II
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Joined: Mon Oct 21, 2013 9:58 am
Posts: 306
Location: Florida
Earl,

Ok, I have a little better understanding of the “heavy duty” reference now. As you mentioned, the changer machines use the heavy duty Type 3 motor. And... I indicated that the Type 3 type of motor (though with a shorter spindle) is seen on other non-changer machines (8-30, 8-60, 12-25, etc) using the same coils, as well as indicating the Type 2, same style motor, is a 25 Hz motor using different coils. What I have come to realize today is that there is the light duty (going by appearances) called a Type 1 motor which also is also used on some non-changer machines (7-26, RE-45, RE-75, etc). The coils are only slightly different in appearance and do measure different than the Type 3. I get 2.5 ohms in the uppers and 152 ohms in the lowers. I’m sure you have come across these two types of motors, but I’ve included a photo showing them below. Also added the page from the RCA Victor Data Book due to pertinence. I do like that the Type 1 style protects more of the motor’s disk, that’s a very good thing.

-Wayne


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96DB393D-3132-492A-9753-C0FD5CD09663.jpeg [ 915.43 KiB | Viewed 128 times ]
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 Post subject: Re: Questions regarding Electrola motors
PostPosted: Sat Jul 14, 2018 8:14 am 
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Victor II
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Joined: Mon Oct 21, 2013 9:58 am
Posts: 306
Location: Florida
Earl (and others),

I have discovered a quick static way of checking out the health of the coils (and wiring) of your VE 10-70 motor without removing the motor, since you said it was running a little hot. At this point, I believe all 10-70, 9=55, and Late-style 10-50 changer motors are connected to the wiring harness via a standard 2 prong plug (all Early/Mid style 10-50s are directly wired to the harness). If you unplug that connection and take a resistance reading between the two prongs, you should get a reading of around 5.4 ohms (for 60 Hz Type 3 motors). I have checked 5 motors this way and get 3 of them to read 5.4 ohms, another read 5.2 ohms, and one a bit higher at 8.1 ohms. It would be interesting to know what your's reads since it's running hot. When I ran the motors for about 10 minutes after dissasembly, cleaning, and oiling/greasing them, I found them to be quite warm, but not too hot that I couldn't hold my hand on them. I was hoping to have an easier way to test the motor's resistance right from the two prongs on the back of the machine (power cord disconnected and switch by the record platter on) but the resistance was quite different than what I read at the motor. I can't explain why, it clearly does not isolate the test to the motor, so I declare it not a good motor test.

Easiest access to the motor plug, is to remove the front wood panel of the changer (first removing the record size selector). I find to put the front wood panel of the changer back on, it takes to then remove the record platter (as well as the metal dust plate under it) and to use hemostats to grab and to hold the reject button support-part from that area, so the button can be aligned with its hole in the wood panel.

Good luck if you decide to try this.


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 Post subject: Re: Questions regarding Electrola motors
PostPosted: Sat Jul 14, 2018 12:49 pm 
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Victor II
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Joined: Thu Jan 15, 2009 7:32 pm
Posts: 367
Location: PA
The main problem in your testing is you are measuring the DC resistance of an AC coil. While this will tell you if the coil is open it won't show a coil with shorted turns as the resistance is so low. You would need to use a 4 wire ohm meter with Kelvin connections to be able to measure the tiny change in DC resistance. The ideal measurement is to measure the impedance (AC resistance) of the coil at or near it's operating frequency, and measure it's inductance which will give a good indication of the coil condition, shorted turns will show a change in the inductance of the coil.

I pulled 4 motors from my junk pile and measured the DC resistance, Impedance and Inductance at 120Hz of each coil using an HP LCR analyzer, I was hoping for a shorted coil but they weren't.

Attachment:
chart.jpg
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There appears to be a problem with the left bottom coil on the Type 4 motor, the DC & AC resistance is higher than expected, but the inductance is in line with the right coil so I would suspect there is a problem with the crimp connection on the wire end.


I'll keep looking for a coil with shorted turns to measure.


Chuck


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