Pioneer PL-520 speed issue Q?

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tlscapital
long player
long player
Belgium
Posts: 1874
Joined: 27 Sep 2015 14:27
Location: Brussels, Belgium

Pioneer PL-520 speed issue Q?

Post by tlscapital » 29 Apr 2019 16:03

A friend has a Pioneer PL-520 turntable that was functioning properly until it started to go up 100 rpm's.

What could be the roots of such issue on such a solid direct drive servo motor turntable ?

Could it be some failing capacitors (then worth the try to fix) or could it be the motor "servo" ?

If it's the last then I understand that it should be less likely worth the "fix"... Advice anyone ?

Coffee Phil
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United States of America
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Re: Pioneer PL-520 speed issue Q?

Post by Coffee Phil » 29 Apr 2019 21:19

Hi tlscapital,

This seems like a nice machine to dump. The manual is here: https://www.vinylengine.com/library/pio ... 510a.shtml

The Hall sensors are working since the machine is spinning. The voltage applied to the three phase stator coils is rectified and compared to a reference voltage to generate the error signal to control the motor. The path from the rectifier diodes through the servo amp will have to be monitored to find out where is stops.

This will require an oscilloscope and a bit more than basic electronics skills.

Hopefully you can find someone local who can do this. I am up to my ears with the speed control on a Kenwood KD 550 for someone on the forum. When I get that resolved I can think of looking at it if you can't find someone local.

Phil


tlscapital wrote:
29 Apr 2019 16:03
A friend has a Pioneer PL-520 turntable that was functioning properly until it started to go up 100 rpm's.

What could be the roots of such issue on such a solid direct drive servo motor turntable ?

Could it be some failing capacitors (then worth the try to fix) or could it be the motor "servo" ?

If it's the last then I understand that it should be less likely worth the "fix"... Advice anyone ?

tlscapital
long player
long player
Belgium
Posts: 1874
Joined: 27 Sep 2015 14:27
Location: Brussels, Belgium

Re: Pioneer PL-520 speed issue Q?

Post by tlscapital » 30 Apr 2019 10:03

Coffee Phil wrote:
29 Apr 2019 21:19
Hi tlscapital,

This seems like a nice machine to dump. The manual is here: https://www.vinylengine.com/library/pio ... 510a.shtml

The Hall sensors are working since the machine is spinning. The voltage applied to the three phase stator coils is rectified and compared to a reference voltage to generate the error signal to control the motor. The path from the rectifier diodes through the servo amp will have to be monitored to find out where is stops.

This will require an oscilloscope and a bit more than basic electronics skills.

Hopefully you can find someone local who can do this. I am up to my ears with the speed control on a Kenwood KD 550 for someone on the forum. When I get that resolved I can think of looking at it if you can't find someone local.

Phil
Hi Phil, it's indeed a fair enough machine. It was passed on to me by a friend who moved away and let me have this turnable that I tested before passing it on to anther friend whose previous cheap DJ-like turntable died. So I do feel "in charge" some. Hence my quest.

And I had indeed the gut feeling that this issue repair would require some specialized tools and tech qualifications more than "elusive" parts. I did read that most of such 'servo motor' failing down turntables do to find their way to the dumpster rather than to the technicians.

I should be able to find someone local to "save" this machine from dismantlement for it's parts but the following question will be; will the cost be worthwhile ? As for my friend without a functioning turntable art the moment, I will lend him my spare Stanton TR8-100 in the meantime.

Fair performer from the Stanton stall, the weak point on this turntable is the tonearm. So I thought to swap it for the Pioneer's one if ever to fix the Pioneer PL-120 proved to be too expensive, complicated or not worth wile. This very Pioneer tonearm is one of the PL-520 "highlight" feature.

Thanks for your support and further insights if ever. Cheers, Tim

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