[GreenKeys] LMU 11 motor

[Bruce Gentry]

Making synchronous motors of this size for the load is difficult, they 
are not as efficient as a regular induction motor and they tend to run 
hot. In all likelyhood, the start condenser has failed, or the start 
relay has failed, or a connection in the starting circuit has failed. 
These motors need a strong start winding current at the correct phase 
shift. Manual starting by spinning the fan is very unlikely to be 
enough. If you could use a drill motor or comparable means to get the 
motor up to several handred RPM it would likely  start. The design of 
the rotor to make the motor synchronous hinders low speed torque, and 
these motors don't have the greatest starting torque under the best of 
conditions. The starting condenser is electrolytic, and passes a heavy 
current for the second or so of starting. It needs to be in good 
condition. Obtaining one that is electrically correct is not difficult,  
but to get one of the same physical size with the correct ratings is  
expensive. I found one offered by a company the specializes in business 
machine parts and repairs. It was not cheap, at about $85.00. By all 
means do more searches.

      Bruce Gentry, KA2IVY




conditions.

On 8/2/22 13:37, Duncanancy wrote:
>
>
> Turned on my 28 RT today and the motor hummed for a minute and then 
> tripped the thermal overload.
> I can turn the motor by hand and it seems normal resistance. When 
> powered, it just seems to wiggle back and forth. Giving a push in the 
> proper direction does nothing.
>
> (On another M28 , the motor would not run until you gave it a push - 
> then it would run. Replacing the motor start cap fixed it.)
>
> But on this 28RT, giving a push doesn't make it run.
>
> Does this sound like the motor start cap?  Any good sources for M-S cap?
>
> Thanks,
>
> Duncan
> K2OEQ
>
>
> Sent from my Kleinschmidt TT-4/TG, the US Army's first portable 
> digital communications device, 1950-1980
>
>
>
>
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