Pioneer PL-50 motor

Try1256

Very Special Member
#1
Rich,
Have you ever opened up the motor on one of these old pioneers? Mine has a slight buzz and from what I have read, the motor bushings can be cleaned which will quiet them down. I dont want to break it but if its an easy process, I am game. Thanks.
 

Try1256

Very Special Member
#5
It’s mechanical. Audio is clean. The motor suspension is doing it’s job as the noise isn’t transferring to the chassis. If I put my ear near the motor I can hear it. Kind of anal about those things.
 

pustelniakr

Silver Miner at Large
Staff member
#6
There is a significant risk to opening such a motor up. Frequently, such motors are sensitive to how everything is aligned upon reassembly. At bicycle shops, there is a teflon bearing lube, called Tri-Flow. If you can get it, spray some in the cap and use a wooden toothpick to pick up a drop and place it on each end of the motor shaft. No more than 2 drops per shaft end. Rotate back and forth with your fingers, to enhance the wicking action into the bushing. Then let it run for a bit without the belt on. If the bushing were binding and that caused the buzz, it might improve.

Otherwise, you may have a loose winding in there. Generally such loose windings happen due to heat, it is will be an interior winding...not correctable.

Good luck,
Rich P
 

Try1256

Very Special Member
#7
Well darn. I was hoping it would be a simple operation. The motor has a little reservoir that holds the oil. It flows through a wick that is in a tube to each bushing. I have heard that the wick and bushing can get gunked up causing noise. I am not sure I can get to the bushing with the teflon. I will have to investigate further. I have ordered a handful of replacement phase caps to replace the original. They are 20% tolerance so I ordered a few. The Thorens that I had developed a little motor buzz and replacing the cap reduced it significantly. I am hoping it will help in this case. Thanks for the advise.
 

pustelniakr

Silver Miner at Large
Staff member
#9
Well darn. I was hoping it would be a simple operation. The motor has a little reservoir that holds the oil. It flows through a wick that is in a tube to each bushing. I have heard that the wick and bushing can get gunked up causing noise. I am not sure I can get to the bushing with the teflon. I will have to investigate further. I have ordered a handful of replacement phase caps to replace the original. They are 20% tolerance so I ordered a few. The Thorens that I had developed a little motor buzz and replacing the cap reduced it significantly. I am hoping it will help in this case. Thanks for the advise.
What kind of caps are they?

If startup/phase caps are bad they could reduce motor torque, resulting is something similar to dirty bushings, where the motor has to work hard.

Enjoy,
Rich P
 

pustelniakr

Silver Miner at Large
Staff member
#11
Those are not likely to be your problem, since they are not likely to be electrolytic, which is the type that ages badly. ON the other hand, replacing them will not be very expensive. I guess it can't hurt.

Good luck,
Rich P
 

pustelniakr

Silver Miner at Large
Staff member
#12
I take my previous statement back. Apparently, 0.1uF 'lytics were pretty common. If yours are 'lytics, there was not alot of electrolyte in there in the first place, so they could certainly have dried up over the years.

Good luck,
Rich P
 

Try1256

Very Special Member
#13
I opened it up tonight with the intention of replacing the cap. Before I removed it, I measured it in circuit and it read .098. Made me have second thoughts. All the ones I got from Mouser measured .090-.092. Decided just to leave it for now. How much would it being still soldered in affect the measurement? Could it still measure in spec but not function properly? Forgive the numerous questions. I know just enough about this stuff to be dangerous. Thanks again Rich.
 

pustelniakr

Silver Miner at Large
Staff member
#14
I never measure or test parts in circuit. That requires a complex network analysis. Just take them out and measure them. Some meters can damage circuit components, and you know what you are seeing. On rare occasion, a part can measure good and still be bad, but that is pretty infrequent.

Enjoy,
Rich P
 
#15
Clean the brushes and the communicator is it persist super glue the field coils.

And replace the start caps. Don't bother testing them they're older than dirt and they take a lot of abuse just replace them they're cheap it doesn't take much time
 

Try1256

Very Special Member
#16
I never measure or test parts in circuit. That requires a complex network analysis. Just take them out and measure them. Some meters can damage circuit components, and you know what you are seeing. On rare occasion, a part can measure good and still be bad, but that is pretty infrequent.

Enjoy,
Rich P
I will probably do that. There are no electronics in the circuit, just power on one side and one motor winding on the other. I thought it might be skewed with the wire and motor winding attached but it was so close to the value it was suppose to be, I thought it would be good to ask before removing it. It is a big axial cap. DK if it is an electrolytic or not. It is pretty old though.
 
#18
Typo in my response. It should read as follows: Clean the brushes and the communicator if the buzz continues super glue the field coils

Hard to explain and even harder to understand by texting. It would be easier to Google electric motor parts or how electric motors work. The very basic concept should be enough to get a get a general understanding.
From there it will all make perfect sense.
 

Try1256

Very Special Member
#19
Typo in my response. It should read as follows: Clean the brushes and the communicator if the buzz continues super glue the field coils

Hard to explain and even harder to understand by texting. It would be easier to Google electric motor parts or how electric motors work. The very basic concept should be enough to get a get a general understanding.
From there it will all make perfect sense.
Thanks! I will look that up.

I changed out the cap last night. Some improvement but there is still a bit of buzz. The vibration I could feel at the motor suspension points is considerably less so that in itself is an improvement. Just for nostalgia sake, I mounted the Pioneer PC-35 cartridge that came with the table last night. It is an "induced magnet" cartridge with a conical stylus. The stylus is an ebay replacement so I don't know how good it is. When I got the table about 6 years ago, it didn't have a stylus so I bought one and used the cart for a very short time before moving to something else. I have learned a bit about TT set up and such since then so I wanted to give it a fair go. Well...Not bad, not bad at all. It has a very "vintage sound" not the last word in detail but it presents a decent sound stage and the tonality is quite nice. I think I will leave it on there a while.
 
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