Pioneer PL-71 Refurbishment

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Alfi
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Re: Pioneer PL-71 Refurbishment

Unread post by Alfi » Wed Jan 10, 2018 1:53 pm

Really sad news for Quarknosis but good new for karatestu. Regarding the loose bearings are they the horizontal plane, or the vertical plane?

I have found the horizontal plane bearings are generally on the slightly loose side with the PL71 and the Sony PS6750 arm to be honest, similar to the Acos built Rega R200 where slight play can be detected.

However if these horizontal bearings are very loose they can be carefully adjusted, but I've maintained a little play with mine. With respect to the vertical bearings, I've not come across any issues yet with all the arms mentioned my post all mine are silky smooth. TBH whilst you can adjust the vertical bearings make sure you obtain (or make special tools for the job that fits very well. If you can do that take great but take care as the cones an balls are easily damaged. J7 is an option too if you don't have the confidence. I've discussed this arm with him a few times as he's worked on a few.

Good luck with the restoration Stu. I'm currently enjoying my PL71 with a Denon DL301 II and DL301-U headshell. No matter what cart you choose I'm sure you'll be pleased with its performance.

My plinth is a bit knocked about so one day I will re-veneer with walnut.

Alfi.
Heavily modified LP12 , Sole VIII sub-chassis with "In Sole" advanced polymer suspension, Ai bearing, PU7, DV20X2, Norton Airpower clone, etc. PL71 & Denon DL301 II, NVA Phono 2 MC (two power supplies), NVA P50, NVA A20 power amp, home made birch ply Allison 6/NVA Cube 1 clones, NVA SSC's, LS6.

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karatestu
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Re: Pioneer PL-71 Refurbishment

Unread post by karatestu » Thu Jan 11, 2018 8:20 am

Thanks for the reply and advice Alfi.

Might try the PL71 with the cartridge i am getting with Les' PT1 - asaka. It is not mounted on the HR100S so easy to try on the Acos. Just to get me started and able to hear what it sounds like now before any fiddling is done.

Bearings - read the J7 thread on Crossovernetwork about rega r200 and it seems that it is a pig of a job with the bearings.

Cheers, Stu
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Vinyl-ant
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Re: Pioneer PL-71 Refurbishment

Unread post by Vinyl-ant » Thu Jan 11, 2018 9:07 am

Rega r200 bearings are not too bad to adjust, just fiddly so patience is needed. They are no worse than any other bearings
Ive just got an acos lustre gst1 to play with, need to make a tool or buy one so the bearings on that one can be tweaked.
Dont know what to fit it to yet
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Alfi
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Re: Pioneer PL-71 Refurbishment

Unread post by Alfi » Thu Jan 11, 2018 9:13 am

Stu
The R200 is similar in looks but is a physically different arm to the PL71's, so don't worry.

The PL71 arm's bias is by spring, making work on the hoz bearings much easier because the bearings can be adjusted without even touching the bias mech. Just make sure it is set to zero before commencing adjustment.

I do not think you will have to dismantle your PL71 horizontal bearings, but if you have stiffness or play in the vertical ones I think you may have to dismantle and gently polish the cones of the adjustment screws. I have two PL71 arms here (one needs a rewire as the "tails" are too short) both have top notch vertical axis bearings and a detachable amount of slight end float in the hoz bearings.

Adjustment of the horizontal axis bearings on the PL71 arm is much easier to undertake but you cannot afford to be heavy handed, all the components in the base are very small and delicate and it doesn't take much adjustment to remove what you may think is excess end float, but as I say most Japanese arms that I have here display a tiny amount of endfloat, I think this was normal just as it was in the Rega (Acos) R200.

The R200's bias is magnetic, before the base can be removed the horizontal axis bearing adjustment nuts have to be removed and the bearings must be replaced exactly as they were removed or you'll have trouble, I have done this work myself on two R200's. It can be done but you need a degree of finesse and much patience.

If you are heavy handed and not careful enough with an R200 you can seriously stuff the bearings. I have one that had been butchered because the cup & cone bearing's caged balls were installed wrong way around (easily done by non engineering people) which popped all the balls out therefore hecouldn't remove play without the arm locking up. Thankfully the cage wasn't too damaged so I was able to re fit the balls using grease and then I washed the entire reassembled cage in solvent to remove the grease. It took me ages to do but I did it and of course re assembled the correct way around. I still have that arm, it's a beauty.



Alfi.
Heavily modified LP12 , Sole VIII sub-chassis with "In Sole" advanced polymer suspension, Ai bearing, PU7, DV20X2, Norton Airpower clone, etc. PL71 & Denon DL301 II, NVA Phono 2 MC (two power supplies), NVA P50, NVA A20 power amp, home made birch ply Allison 6/NVA Cube 1 clones, NVA SSC's, LS6.

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karatestu
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Re: Pioneer PL-71 Refurbishment

Unread post by karatestu » Thu Jan 11, 2018 10:37 am

Thanks Ant & Alfi.

It is a relief that the PL71 arm is different to the R200 as that thread on CN is a real horror story for the unexperienced !

Alfi - when you say "a detachable amount of slight end float" what exactly do you mean ?

The arm vertical bearings seem ok to me but I am a novice, there is no play in them but I would not know how to check them for sticking points (if there are any).

The hoz bearings - I can move the whole arm pillar side to side or front to back by at least half a mm . You can hear it clanking / chattering when doing this. Does this sound excessive ? Getting the arm to float and pushing it extremely gently from rest to spindle and back produces a beautifully gentle swing with no sticking at any point. That is encouraging but my obsessive brain can't help wondering about the wobble in the hoz bearing and the chatter it makes.

I can be heavy handed when I know I can get away with it but also have learnt over the years to be delicate when needed (breaking things is a learning process :roll: )

Regards, Stu
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Dr Bunsen Honeydew
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Re: Pioneer PL-71 Refurbishment

Unread post by Dr Bunsen Honeydew » Thu Jan 11, 2018 10:42 am

Just don't use the chain saw :mrgreen:

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karatestu
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Re: Pioneer PL-71 Refurbishment

Unread post by karatestu » Thu Jan 11, 2018 10:58 am

Image
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Alfi
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Re: Pioneer PL-71 Refurbishment

Unread post by Alfi » Thu Jan 11, 2018 11:19 am

karatestu wrote:
Thu Jan 11, 2018 10:37 am
Thanks Ant & Alfi.

It is a relief that the PL71 arm is different to the R200 as that thread on CN is a real horror story for the unexperienced !

Alfi - when you say "a detachable amount of slight end float" what exactly do you mean ?

The hoz bearings - I can move the whole arm pillar side to side or front to back by at least half a mm . You can hear it clanking / chattering when doing this. Does this sound excessive ? Getting the arm to float and pushing it extremely gently from rest to spindle and back produces a beautifully gentle swing with no sticking at any point. That is encouraging but my obsessive brain can't help wondering about the wobble in the hoz bearing and the chatter it makes.



Regards, Stu
By your explanation it does appear excessive and while it moves freely, I too would want to reduce the play for reasons you mention, especially if using a low compliance MC that dumps a lot of energy into the arm. Good news is it's an easy fix to reduce that play on the PL71 arm. If you remove the arm from the table you will see that it's all pretty intuitive underneath in getting to the bearings. Carefully remove the two small screws securing the arm pillar to the plastic bias housing and you will clearly see the hoz bearings with their adjustment & locking nuts, make the adjustment, refit the steel tube to the bias housing and test hith the arm back on the deck, you may have ot do this a few times until you've got it where it needs to be before finally refitting and re attaching the wires.

With my PL71 arm at rest and restrained by the arm clip. If I firmly (but gently) hold the vertical bearing yoke by the vertical bearing caps I can feel a tiny amount of vertical end float in the yoke assembly, it's hardly anything but I certainly cannot move the yoke side to side. I could probably force it to, but that would be really levering it which would actually cause the plastic shroud containing the bias mech to flex - don't want to be doing that!


Good luck.

Alfi.
Heavily modified LP12 , Sole VIII sub-chassis with "In Sole" advanced polymer suspension, Ai bearing, PU7, DV20X2, Norton Airpower clone, etc. PL71 & Denon DL301 II, NVA Phono 2 MC (two power supplies), NVA P50, NVA A20 power amp, home made birch ply Allison 6/NVA Cube 1 clones, NVA SSC's, LS6.

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karatestu
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Re: Pioneer PL-71 Refurbishment

Unread post by karatestu » Thu Jan 11, 2018 11:38 am

Cheers Alfi, you have helped me no end there.

One other thing for any one who knows. I can't remove the platter from the deck. Is this normal ? It does raise a few mm when you pull upwards with fingers in the two holes on the top surface of the platter. I presumed it must be able to come off because the packaging diagram on the pdf I downloaded from vinylengine clearly shows the platter off and contained in it's own part of the polystyrene packaging.

This has me puzzled somewhat. Could it be seized on or am I being a numpty and missing something obvious ?I don't want to be pulling too hard and damaging something in the bearing. :cry:

Stu
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Dr Bunsen Honeydew
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Re: Pioneer PL-71 Refurbishment

Unread post by Dr Bunsen Honeydew » Thu Jan 11, 2018 11:58 am

Just pull harder it is a compression fit, it comes off.

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