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Adjusting PL-71 Tonearm Bearings

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Adjusting PL-71 Tonearm Bearings

Postby royal_mile » 07 Jan 2018 18:47

Just a few notes on adjusting column bearing free play on the Pioneer PL-71 or PL-1400.

I noticed the arm on my turntable was very smooth but did have some free play in the bearing area and this was probably outside the mfr tolerances. The symptom was a slight rocking movement within the column rather than the bearings on the arm tube.

The arm looks similar to one of the early Rega models (made by Acos?) but the bearings, anti-skate and mounting are all completely different.

To fix the problem, I took the arm off the turntable and removed the arm upper bearing and tube from the base column.

Here's a few notes and pictures:
1. First I removed the arm by tipping the turntable upside down (counterweight, headshell and platter removed) on a stack of books to keep the arm above the work surface.
2. Removed the base, desolder the thin tonearm wires. Support the arm from the top then undo the mounting nut.

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3. With the arm off the turnable, locate the and removed two black socket headed grub screws in the centre column. Ease the upper assembly and bearing out of the column.

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4. The bearing assembly can accessed. To adjust the bearing, slacken the slotted grub screw on the brass nut assembly and turn the nut until the free play has been eliminated. Take care, a little play is better than a binding bearing.

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5. Re-assemble taking great care to align the anti-skate leaver with the plastic pin and flattened area of the inner column. It is good to see the arm doesn't have the Rega toothed anti-skate belt but uses a spring mechanism instead.

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Re: Adjusting PL-71 Tonearm Bearings

Postby karatestu » 08 Jan 2018 10:20

Thanks Royal Mile, a very informative and useful post.

You seem to know what you are doing with these things. I am on a very steep learning curve as regards repairing/servicing turntables and have just acquired a PL71 which needs some tlc, including all the tonearm bearings.

It is good to know the anti skate is on a spring rather than the belts which are said to disintegrate.

Stu
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Re: Adjusting PL-71 Tonearm Bearings

Postby DSJR » 11 Jan 2018 18:05

I don't know how different the lateral bearings are from the vaguely similar Rega R200, but according to Roy Gandy (I don't mean to name-drop but I did have this chat with him way back) gravity alone is supposed to load the horizontal bearing race so you may not need to remove 'all' the free play here if the ball races are remotely similar - a certain PL-71 known to Stu and I played incredibly happily with a mid period Ortofon SPU and with a superb sense of precision, something that can get lost if the arm isn't behaving itself properly in my experience.
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Re: Adjusting PL-71 Tonearm Bearings

Postby karatestu » 12 Jan 2018 15:04

DSJR wrote:I don't know how different the lateral bearings are from the vaguely similar Rega R200, but according to Roy Gandy (I don't mean to name-drop but I did have this chat with him way back) gravity alone is supposed to load the horizontal bearing race so you may not need to remove 'all' the free play here if the ball races are remotely similar - a certain PL-71 known to Stu and I played incredibly happily with a mid period Ortofon SPU and with a superb sense of precision, something that can get lost if the arm isn't behaving itself properly in my experience.


Hello Dave,

I think you are right, if tightening up the horizontal bearing you should leave some play. The bearings seem to be alot easier to work on than in the Rega R200. I'm hoping so anyway :D
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Re: Adjusting PL-71 Tonearm Bearings

Postby DSJR » 12 Jan 2018 15:24

Good luck with your restoration. It's a lovely 'sounding' deck once working right - such a shame it didn't seem to be around for long in the UK.
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Re: Adjusting PL-71 Tonearm Bearings

Postby royal_mile » 20 Jan 2018 17:24

DSJR wrote:I don't know how different the lateral bearings are from the vaguely similar Rega R200, but according to Roy Gandy (I don't mean to name-drop but I did have this chat with him way back) gravity alone is supposed to load the horizontal bearing race so you may not need to remove 'all' the free play here if the ball races are remotely similar - a certain PL-71 known to Stu and I played incredibly happily with a mid period Ortofon SPU and with a superb sense of precision, something that can get lost if the arm isn't behaving itself properly in my experience.


Yes I agree with this it is better to have a little free play, the arm on my pl was very wobbly. I took most of the play out then backed off a little leaving a tiny amount of movement.

Steve
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Re: Adjusting PL-71 Tonearm Bearings

Postby royal_mile » 20 Jan 2018 17:29

karatestu wrote:Thanks Royal Mile, a very informative and useful post.

You seem to know what you are doing with these things. I am on a very steep learning curve as regards repairing/servicing turntables and have just acquired a PL71 which needs some tlc, including all the tonearm bearings.

It is good to know the anti skate is on a spring rather than the belts which are said to disintegrate.

Stu


Good luck with the restoration Stu, the PL71 is a wonderful turntable and quite nice to work on. I had to replace the speed switches on mine, a common fault. Other than that, it has been stable and reliable.

Steve
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Re: Adjusting PL-71 Tonearm Bearings

Postby karatestu » 21 Jan 2018 17:14

royal_mile wrote:
karatestu wrote:Thanks Royal Mile, a very informative and useful post.

You seem to know what you are doing with these things. I am on a very steep learning curve as regards repairing/servicing turntables and have just acquired a PL71 which needs some tlc, including all the tonearm bearings.

It is good to know the anti skate is on a spring rather than the belts which are said to disintegrate.

Stu


Good luck with the restoration Stu, the PL71 is a wonderful turntable and quite nice to work on. I had to replace the speed switches on mine, a common fault. Other than that, it has been stable and reliable.

Steve


Thanks Steve.

I am looking forward to getting stuck in. The previous user of this PL71 reported inner groove distortion which i am assuming is caused by the excessive play in the horizontal bearings. I have not played it yet but i will before i take the arm off.

Your pictures and write up is a great Help, thanks.

Stu
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