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AR XA motor/pulley noise

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DijonMaster

Active Member
I've been trying to fix up my thrifted Acoustic Research XA. The motor seems to have a loud buzz/grind to it, but only when it's low in the shaft. If I pick up the motor spindle a bit or put a piece of felt to separate it from the plinth, the noise quiets down significantly.

The noise gets worse when I add the pulley. The pulley also seems like it's shaking slightly, causing the noise.

Any advice? I oiled the motor
 
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Oil the motor with a light oil (e.g. sewing machine oil) and let it run for a couple of days. Every few hours wipe away what will probably be dirty oil and then add a drop or two. Repeat over the couple of days the motor is running. Doing this will cause the gunk in the motor to well up and out. The motor and pulley will normally vibrate a tiny bit when the table is plugged in; nothing to sweat.
 
Yeah, there definitely seems to be black gunk that builds up on the motor spindle. Is that gunk that's stuck inside the motor or is it just oil I add that gets dirty from soot?

Also, the motor spindle spins well when it's not all the way inserted (it comes up a a bit out of the motor housing). When it falls down is when it makes the grinding noise.
 
DijonMaster said:
Yeah, there definitely seems to be black gunk that builds up on the motor spindle. Is that gunk that's stuck inside the motor or is it just oil I add that gets dirty from soot?

Also, the motor spindle spins well when it's not all the way inserted (it comes up a a bit out of the motor housing). When it falls down is when it makes the grinding noise.
Click to expand...

The noise is probably from the black gunk but the new oil and running it continuously for a couple of days will circulate it out. I bet many of the ARs folks get have been sitting for a long time so there is less oil in the motor and it is dirty. If the oil still has black soot in it after a couple of days just keep adding oil and letting it run. It's tedious but that process works to quiet the motor.
 
Is it possible that the pulley is low enough on the shaft that it is contacting the motor body? The pulley is just a press fit, so it can get shoved too low, and pulling up on the shaft, as you have done,would keep the pulley from rubbing. If the pulley is low, pull up hard enough to move it up the shaft.
 
Nat said:
Is it possible that the pulley is low enough on the shaft that it is contacting the motor body? The pulley is just a press fit, so it can get shoved too low, and pulling up on the shaft, as you have done,would keep the pulley from rubbing. If the pulley is low, pull up hard enough to move it up the shaft.
Click to expand...

If I pull up, the weight of the pulley presses it down again. Without the pulley, i can pull the motor up a bit and it spins quietly
 
DijonMaster said:
If I pull up, the weight of the pulley presses it down again. Without the pulley, i can pull the motor up a bit and it spins quietly
Click to expand...

It might be easier to blot up the dirty oil and add the next couple of drops if the pulley has been removed. I'm not sure it will make any difference in how long it takes to clean up motor however.
 
AvFan said:
It might be easier to blot up the dirty oil and add the next couple of drops if the pulley has been removed. I'm not sure it will make any difference in how long it takes to clean up motor however.
Click to expand...

So there's no more black gunk coming out. The noise only happens when the motor spindle is fully down (it lifts up a little). When lifted, the motor is quiet. It's almost like it's grinding on something
 
If you remove the can covering the motor you can see the bottom of the spindle. May need to tear it all the way down.
 
do these have the same sort of thrust surface wear issue that the Thorens motors are prone to? There is a fix for it on the Thorens motors, if the shaft sticks out the bottom of the AR motor it seems likely a similar repair could be made there.


The Thorens ones you glue a plastic sleeve to. The sleeve is hollow and threaded. A bearing ball sits in there and a screw comes in from the bottom. Basically you adjust the screw so that the bearing ball pushes the motor shaft up enough to get it off the worn thrust surface in order to stop the noise.

Thorens Turntable Motor Spindle Support Kit Eliminate Knocking - Vinyl Nirvana - Vintage AR and Thorens Turntable Sales, Parts, and Restorations
 
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