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AC Motor circuit Problem

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New Member
Hello Everyone,

I'm having what appears to a problem with the AC motor circuit on a reel to reel tape machine. With no tape reels on the machine(Unloaded), the motors themselves seem to be working ok, though the take-up reel often needs to be given a hand turn to get started. When loaded, the take-up reel simply can't pull the load, neither can the supply reel during rewind. So the problem seems to be one of the motors lacking adequate torque. The motors are rated at 60V. During operation each is receiving 17.8V. Unfortunately without schematic I do not know if this is the correct voltage. I've checked the start cap with an ohmmeter. Both sides seem to charge ok. Definitely no short or open. Could this cap still be too weak for proper operation? Or is there anything else that may be responsible for losing adequate torque/voltage to the motors? I'm posting here in case there is something I've overlooked before removing/replacing the capacitor(quite a job in this case)

Thanks to all in advance


New Member
These are very low torque motors and the slightest bearing load will make the motor seem dead. The motor may seem to turn freely, but the slightest bearing losses take a big toll on takeup and rewind.

I've found that on my old reel to reel tape recorders (and old turntables) the most common motor failure is the bearing. 40+ years ago, the favorite material was sintered bronze, soaked in light oil. Guess what happens to light oil in 40 years?

My solution is to apply a drop of 'sewing machine oil' or '3-in-1' oil to the motor bearings after the motor has warmed up. It usually keeps it working for another 5-10 years. The motor must be warm. You should run the motor for at least a day after applying the oil and then apply more. Wipe up any that drips away.

I don't suggest WD-40 because it will evaporate and you'll be taking it apart every six months.
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