PL-71 restoration

the final frontier
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6L6
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PL-71 restoration

Post by 6L6 » 15 Dec 2014 21:46

This thread will be for the documentation of the restoration and (probable) modification to a Pioneer PL-71 turntable.

Why the PL-71? A couple of reasons:

1) It's a good example of pre-PLL direct drive. The motor is very quiet and it's bearing structure are good.

2) It has a wonderful tonearm made by Acos.

3) The turntable is generally considered to be a good example of "better than the sum of it's (quite nice) parts".

4) It's the turntable I grew up with, and 5) I didn't actually expect to win the auction. :)

http://www.diyaudio.com/forums/gallery/ ... G_2428.jpg
Here it is in the condition I recieved it. The wood is a bit dry, there is a general light yellowing of all the metal parts indicative of it living in a smoker's household at some point, but other than that, it's in very nice shape.

http://www.diyaudio.com/forums/gallery/ ... G_2431.jpg
And here it is after a thorough cleaning. The yellowish tint is off the metal, the wood has a coat of Danish oil, and generally it look much, much better.

I didn't take any photos as I was cleaning it, just imagine a bunch of paper towels, cotton swabs, alcohol, wood oil and the like all strewn about. It took approximately 1.5-2hr of scrubbing, dabbing, cleaning, wiping, brushing and elbow grease.

I still need to treat the mat, it's clean, but the rubber needs something to restore a bit of moisture to it.

http://www.diyaudio.com/forums/gallery/ ... G_2433.jpg

http://www.diyaudio.com/forums/gallery/ ... G_2435.jpg
The dustcover is is great shape for it's age. I'm very pleased.

http://www.diyaudio.com/forums/gallery/ ... 2436-1.jpg
The bottom cover is very 1973. But the metal chassis bottom is a neat piece, making a metal interface for the sprung feet into the wood chassis that makes up the rest of the table.

http://www.diyaudio.com/forums/gallery/ ... G_2437.jpg
Here's the up-skirt shot.

http://www.diyaudio.com/forums/gallery/ ... G_2448.jpg

http://www.diyaudio.com/forums/gallery/ ... G_2441.jpg
A few things worth mentioning, the tonearm is rigidly coupled into the chassis, and with the tagboard and jacks easily removed, would be a good candidate for a continuous rewire or conversion to DIN if that's you kind of thing.


http://www.diyaudio.com/forums/gallery/ ... G_2439.jpg
This board is mainly for AC distribution.

http://www.diyaudio.com/forums/gallery/ ... G_2438.jpg
DC rectifier and 'regulator' (Really just a zener-referenced cap multiplier.)

http://www.diyaudio.com/forums/gallery/ ... _24401.jpg
The power/speed selector switches and speed trim pots.

http://www.diyaudio.com/forums/gallery/ ... G_2442.jpg
These little screws holding the motor cover were a royal pain to remove.

The power transformer is mounted on rubber feet. Remarkably quiet. Of course it would benefit from being in it's own external case, and I may try that. It also has a universal primary and voltage selection with one of those neat plug thingys.

The motor is rigidly coupled to the chassis and the control board is under the black cover.

http://www.diyaudio.com/forums/gallery/ ... G_2445.jpg
Cover removed showing the motor control PCB. The 38yr-old capacitors need to be replaced.

http://www.diyaudio.com/forums/gallery/ ... G_2446.jpg
Not too bad of a job. There are a number of wires that got the the motor windings on the other side of the PCB that seemed to be in the way, but other than that, it's straightforward. No values changed

http://www.diyaudio.com/forums/gallery/ ... G_2443.jpg
The regulator board also got a set of fresh capacitors. The filter caps are a bit bigger than stock, but the can size is still the same. :cool:

http://www.diyaudio.com/forums/gallery/ ... G_2447.jpg
Dead soldiers.

http://www.diyaudio.com/forums/gallery/ ... G_2450.jpg
I replaced some screws that hold the strobe to the chassis, over the years 3 of the 4 screws had fallen out. I had to scrounge for hardware that fit, but now it's solid.


http://www.diyaudio.com/forums/gallery/ ... G_2451.jpg
Lastly I added some secret lubricant to the bearing, I got it from a kindly old Dutchman who horse-swapped it from a Polar Bear named SY. I have little idea what's actually in it, other than it was made for low-heat, high-pressure interfaces, specifically TT bearings.


In my opinion, all I did was to get the 38-yr old table back in a condition similar to when it left the factory. So far it's just a tune-up, no hot-rodding, no mods.

Yet.

:)


Edit -

There has been a number of reports of people trying different mats, and always returning to the stock one. I have a theory why -

https://www.youtube.com/watch?v=zxbj0a-AzuI

vs music
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Posts: 237
Joined: 08 Feb 2011 02:18
Location: Murmansk - Russia

Re: PL-71 restoration

Post by vs music » 15 Dec 2014 23:51

Beautiful turntable ! =D> Good work! =D> Good cartridge Empire ! =D>

Alec124c41
vinyl engineer
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Canada
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Re: PL-71 restoration

Post by Alec124c41 » 18 Dec 2014 21:09

Lovely. :)
That will reward you well.

Cheers,
Alec

6L6
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Joined: 25 Jun 2013 00:30

Re: PL-71 restoration

Post by 6L6 » 21 Dec 2014 18:18

Alignment - the stock suggested alignment (14.5mm overhang) is quite odd. Playing around with some of my old carts yielded strange results. Baerwald didn't seem to work either...

After playing around a bit, and suspecting that perhaps it was more the cartridge than the alignment I ordered a new cheap and cheerful cart, when I found that;

My old "keep them around for a rainy day" cartridges were all worn out. I guess I didn't realize how bad they had gotten.

Putting the new cart in the stock headshell sounds really quite wonderful. Alignment is plain Baerwald set with my Geodisc.

Problem fixed.

It's now a genuinely nice sounding table. Very together, very musical, very sorted. I like it an awful lot.

http://www.diyaudio.com/forums/gallery/ ... G_2478.JPG

SolidPL
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Norway
Posts: 16
Joined: 25 Apr 2014 20:18

Re: PL-71 restoration

Post by SolidPL » 21 Dec 2014 22:11

Congrats with your new turntable.Looks mighty fine.
Thanks for sharing :-)

blas62
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Posts: 5
Joined: 04 Jan 2018 14:26

Re: PL-71 restoration

Post by blas62 » 29 Apr 2019 15:58

Hello
I reboot this thread because I am restoring a pl-51a and when changing the capacitors of the motor controller a red wire has been released (it will be the positive one) and I do not remember where it was connected. Do not take photos. I would appreciate someone uploading a photo to repair it.
Thank you.

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