PL-570 Restoration

[the_burmese]

Hi folks

Been a while. Recently found my dream table: the PL-570. It is really beat up but cosmetics are not a concern. I plan to redo the veneer.

It is the functional issues that I'd like to get some help.

First thing I noticed is that the unit would just start turning as soon as it is plugged in. Cant be stopped with the stop button. I can also hear some sort of grinding noise around the tonearm control mechanism.

I have done some work in PL-540 but 570 is NOTHING compared to 540.
Some pointers on where to start would be greatly appreciated.

thanks!

 

[AE Bob]

If the white cam wheel does not turn, and you are hearing a buzzing sound from that area, it is likely the geared "timing" motor is internally gummed up. You have to do some rather serious disassembly to correct it (arm drive assembly removed, screw in cam gear loosened, and motor removed from the arm drive assembly). The motor needs to be removed, and the gear assembly removed from the motor, dismantled, cleaned and lubricated, and reassembled (as well as lubricating the motor shaft). I have done several. The gear assembly "unclips" from the motor assembly. The lubricant inside the motor and gear assembly hardens up, and causes no motion.

 

[the_burmese]

Hi Bob

Thank you for your advice. It appears it is the case - the cam wheel does not turn and the buzzing IS from the arm motor.



I am trying to tear down that assembly but I am not sure how to disconnect those two cable connections.
They are hooked with plastic stoppers so I am worried if I don't do it right, they would break off.

Or do you disconnect them from the other ends?

Here is one for the REPEAT control -



Another for the STOP I think -

 

[AE Bob]

I unscrew the cable sleeve mount, and remove the circlip, and plastic arm from the shaft, and remount everything when done.

Actually I think I have been leaving one still connected (the long one), and been really careful not to stress it when removing the motor from the base plate.

 

[the_burmese]

I unscrew the cable sleeve mount, and remove the circlip, and plastic arm from the shaft, and remount everything when done.

Actually I think I have been leaving one still connected (the long one), and been really careful not to stress it when removing the motor from the base plate.

Yeap, you probably have been. I quickly learnt there is no way the long one would come off without tearing down all the arm connections on top. Did exactly that to the shorter one.

Now the motor is out and gear housing is separated. The axle would not turn and I can see it is all gummed up in there.
How do I open this housing? Pry the metal lid off? Is it glued to the plastic housing? Score the rim with an X-acto knife?

 

[AE Bob]

It should just easily lift off. It may be "glued" on by the gummed up grease.

 

[the_burmese]

Thanks. It was indeed locked up with the gum.
Sprayed some WD-40 and tapped the axle a little and it popped right off.

This is after cleaning.


Unfortunately one of the gear has a crack.


I tried to put a small amount of super glue for now. I don't think it will be easy to find this part

What kind of grease should I put back in? This is what I am planning to use.

 

[AE Bob]

Check to see if the gear binds when the crack engages the other gear. You will likely need to repair the cracked gear, or it may jam where the teeth are too far apart.. I repair them by pressing the plastic gear off the shaft, enlarging the hole in the gear slightly, being careful to enlarge it just enough that the crack doesn't open when the gear is put back on the shaft. I use a tiny diamond grinder bit in my Dremel tool to enlarge the hole (it is the only thing I have found that cuts that plastic well). I then clean everything up really well, and glue the crack in the gear, and glue the gear to the shaft with gel CA glue.

https://www.ebay.com/itm/402368043518?hash=item5daf0119fe:g:GDkAAOSwyG1fPO4v

 

[AE Bob]

I use a silicone grease (as it does not deteriorate), but I believe any good grease will do (like phono lube)

 

[the_burmese]

Appreciate the detailed instruction. I tried to rotate the assembly and the gears are not jammed or slipping at the cracked location. Note that i have put some super glue in the crack in previous step.




I will try this first. If it doesn't work, I will definitely follow exactly what you did with the grinder tool. A bit worried that it would shattered when it is being pushed out of the shaft.
Ordered silicone grease from Amazon. I will report back once it has been put back together and tested.

 

[AE Bob]

If the gears are not jamming or giving strong resistance when the crack passes, you will likely be fine.

 

[the_burmese]

Lubed and reinstalled. Alighted the gear position as below.
Now the platter is not constantly spinning. And the grinding noise is gone.



However, auto start is NOT working. I can move the tonearm manually and the platter would start to spin ( manual mode is working well now )
I can hear the arm control motor turning when start button is pushed.
I also double checked the shaft to gear connection.
Not sure why the main gear would not turn.

 

[the_burmese]

also, if I press STOP button, the platter would spin ....

A little bit of good news is that the quartz lock is working for both 33.33 and 45 rpms. It's dead on.

 

[perpetualwar]

I will be watching this thread closely. Thanks for all the detailed photos so far!

 

[AE Bob]

Be sure you tightened the screw that locks the gear to the gear motor shaft. Check to see if the cam gear is jammed somehow. Make sure the gear motor is working (output shaft turning when motor runs). ????????????

 

[the_burmese]

Be sure you tightened the screw that locks the gear to the gear motor shaft. Check to see if the cam gear is jammed somehow. Make sure the gear motor is working (output shaft turning when motor runs). ????????????

Hi Bob

The motor is confirmed working. Because after good alignment with the cam gear, it rotates about a quarter turn! However, it is jammed after 1/4 turn. I tried a few times to lube and wiggle the jam but unfortunately, now small gear attached to the shaft has broken teeth.
The broken teeth are next to the crack in the gear so I believe the torque is parting the crack and making the gear stuck at this position. And my wiggling probably took out the teeth. (lesson learnt!)



I am not trying to figure out how to replace this gear. Working on CAD design and printing a replica with a nylon printer.
How do you take out the shaft from the gear? Does the shaft has teeth to lock between it and the hole in the gear?

Thanks!

 

[AE Bob]

If I remember correctly the shaft is knurled in the area where the gear is molded on. I have had units where the gear was split in half, and I ground the knurl from the inside of the gear halves, and enlarged the hole, to where the gear could be put on the shaft without opening the gap between the halves. I then glued the gear back together and back on the shaft with Gel CA glue.

In your case, if you have a newly fabricated gear, you might want to grind some of the knurl from the shaft, then glue your gear on.

 

[the_burmese]

If I remember correctly the shaft is knurled in the area where the gear is molded on. I have had units where the gear was split in half, and I ground the knurl from the inside of the gear halves, and enlarged the hole, to where the gear could be put on the shaft without opening the gap between the halves. I then glued the gear back together and back on the shaft with Gel CA glue.

In your case, if you have a newly fabricated gear, you might want to grind some of the knurl from the shaft, then glue your gear on.

Appreciate so much. Will probably try with a bit larger hole in the gear first and see how it goes. I think knurls on one side might be needed to keep it from slipping.

Will keep you updated.

 

[the_burmese]

Got 3D printed gears today!!

They are REALLY strong and very close in dimensions. But I got the bore size wrong because I didnt factor that brass sleeve inside. Will need to figure out how to open up the bore a little bit. I have a few printed so should be able to do some trial and error.

 

[AE Bob]

You might be able to heat the brass sleeve (to expand it) and pull it off the inner spline, then just bond the gear directly to the spline on the shaft itself.