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.
Fantastic reference thread here - A new toy - PL-71.....
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.
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.
The dustcover is is great shape for it's age. I'm very pleased.
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.
Here's the up-skirt shot.
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.
This board is mainly for AC distribution.
DC rectifier and 'regulator' (Really just a zener-referenced cap multiplier.)
The power/speed selector switches and speed trim pots.
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.
Cover removed showing the motor control PCB. The 38yr-old capacitors need to be replaced. (Yes, one is already replaced in this photo...)
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
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.
Dead soldiers.
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.
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 -
(click link for video) https://www.youtube.com/watch?v=zxbj0a-AzuI
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.
Fantastic reference thread here - A new toy - PL-71.....
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.
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.
The dustcover is is great shape for it's age. I'm very pleased.
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.
Here's the up-skirt shot.
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.
This board is mainly for AC distribution.
DC rectifier and 'regulator' (Really just a zener-referenced cap multiplier.)
The power/speed selector switches and speed trim pots.
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.
Cover removed showing the motor control PCB. The 38yr-old capacitors need to be replaced. (Yes, one is already replaced in this photo...)
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
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.
Dead soldiers.
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.
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 -
(click link for video) https://www.youtube.com/watch?v=zxbj0a-AzuI
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Great little turntable!
I also love to restore these old fellas.
By the way, I can only recommend to replace the speed trim pots too; while they might still be good, I don't see much reason why they should last another 10 years.
They look like the standard 17mm pots that are available from Mouser or Digikey (being made by Bourns). While the 70ies and 80ies standard manufacturer of those things - ALPS - still makes pots, they are hard to come by as the common distributors stock only few configurations of these. For some reason the Bourns range is very well stocked though.
I also love to restore these old fellas.
By the way, I can only recommend to replace the speed trim pots too; while they might still be good, I don't see much reason why they should last another 10 years.
They look like the standard 17mm pots that are available from Mouser or Digikey (being made by Bourns). While the 70ies and 80ies standard manufacturer of those things - ALPS - still makes pots, they are hard to come by as the common distributors stock only few configurations of these. For some reason the Bourns range is very well stocked though.
Hannes - A good point, and I will see if there are some pots available that fit the mount.
The real issue is that the speed selector switches are in series with the pot, and if there is any contact resistance it changes the speed of the platter. (Remember, this is pre-PLL direct-drive) In the case of this particular table, the 33RPM switch is fine, but the 45RPM switch is not quite right. I need to replace the microswitches as part of the general tune-up.
Kevin - A different arm might be a bit of a bodge from the aesthetics standpoint - the trimpiece on the right side of the table is fit for that specific mount. So it would look quite wonky if it had a different base. That, and it's quite a nice arm in it's own right, most people attribute the performance of the deck to the arm. I'm inclined to agree. (And my SP-10 is a much more logical and easy platform for arm swapping... )
The platter is nice, cast and then machined in spots, it's about the same mass as the SL-1200. Rings like a bell as there is no damping other than the mat. I know a few people who go gaga over filling the inside of these kind of platters with a specific epoxy, (WEST SYSTEM G/Flex 650 Liquid Epoxy, 8 oz. (One 4 oz. bottle of resin, one 4 oz. bottle of hardener) | West Marine) As this platter has no damping inside, it platter would be a good candidate, just need to plug the fingerholes.
From a project point of view, the general plan is to get it back to a stock condition, then make a mod to the DC regulator (add a TL431 in place of the zener, that should reduce ripple by an awful lot) and perhaps rewire the arm.
The other thing I have seen done is replace the motor with a slightly newer PLL version from a different Pioneer, which happens to be mechanically a drop-in to the existing mount, but tracking down that motor might be difficult. (That, and I'm not exactily hurting for turntables right now... )
The real issue is that the speed selector switches are in series with the pot, and if there is any contact resistance it changes the speed of the platter. (Remember, this is pre-PLL direct-drive) In the case of this particular table, the 33RPM switch is fine, but the 45RPM switch is not quite right. I need to replace the microswitches as part of the general tune-up.
Kevin - A different arm might be a bit of a bodge from the aesthetics standpoint - the trimpiece on the right side of the table is fit for that specific mount. So it would look quite wonky if it had a different base. That, and it's quite a nice arm in it's own right, most people attribute the performance of the deck to the arm. I'm inclined to agree. (And my SP-10 is a much more logical and easy platform for arm swapping...
)The platter is nice, cast and then machined in spots, it's about the same mass as the SL-1200. Rings like a bell as there is no damping other than the mat. I know a few people who go gaga over filling the inside of these kind of platters with a specific epoxy, (WEST SYSTEM G/Flex 650 Liquid Epoxy, 8 oz. (One 4 oz. bottle of resin, one 4 oz. bottle of hardener) | West Marine) As this platter has no damping inside, it platter would be a good candidate, just need to plug the fingerholes.
From a project point of view, the general plan is to get it back to a stock condition, then make a mod to the DC regulator (add a TL431 in place of the zener, that should reduce ripple by an awful lot) and perhaps rewire the arm.
The other thing I have seen done is replace the motor with a slightly newer PLL version from a different Pioneer, which happens to be mechanically a drop-in to the existing mount, but tracking down that motor might be difficult. (That, and I'm not exactily hurting for turntables right now...
)
Figured damping the platter and building a fairly massive plinth and making provisions for easily swapping arms.
That's quite a bit of work though, and I guess the question is whether the underlying hardware justifies that sort of effort.
It does look pretty well made and I was kind of thinking along the lines of a poor man's SP-10, but you have the real deal.
FWIW it is way better than anything I had in the time frame when this table was new..
That's quite a bit of work though, and I guess the question is whether the underlying hardware justifies that sort of effort.
It does look pretty well made and I was kind of thinking along the lines of a poor man's SP-10, but you have the real deal.
FWIW it is way better than anything I had in the time frame when this table was new..
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.
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.
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Nice. I have a similar project to complete one day. The underside of my Onkyo CP700M is practically the same as your Pioneer. Styling is similar too.
Onkyo CP-700M
This is my only table, though, so I've Deoxited the speed pots, replaced the caps and speed is now dead stable. I'm pretty sure the arm is also an Acos derived example, as it has features very similar to my Rega R200, such as the disintegrating anti skate belt.
This table has an interesting rubber sandwich construction where the top is isolated from the bottom.
Onkyo CP-700M
This is my only table, though, so I've Deoxited the speed pots, replaced the caps and speed is now dead stable. I'm pretty sure the arm is also an Acos derived example, as it has features very similar to my Rega R200, such as the disintegrating anti skate belt.
This table has an interesting rubber sandwich construction where the top is isolated from the bottom.
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Kimi says woof!
Love and hug her for me.
My avatar photo, ZoeBear, passed just 2 days ago Friday.
She was a great dog.
I have flipped it once; next time I'll take a snap. It has that circular PCB on the bottom of the motor, just like yours. And is not quartz locked.
The anti skate is magnetic, but the adjustment of the magnet is done via a belt which eventually disintegrates. I think I can use a small toothed belt from a printer etc. to make another.
Anyway, I'll be looking at this thread with interest, as I'd imagine the workings are similar - the way the speed is controlled etc.
Thanks 6L6. Your guide on re-capping was a great. The pics were perfect.
We found a beautiful PL-71 at a garage sale for 5 bucks a couple years ago. It fired right up and ran great until last week when both speeds dropped to about half. I have cleaned all pots and switches, re-capped the power supply, control board, and motor (BTW, for anyone else doing this, the values of the motor capacitors are 4 - 4.7uF and 3 - 10uF, since they aren't listed in the service manual).
But this beauty still is running at about half speed. Next step is replacing switches and pots. But could the motor itself be shot? I'm trying to identify what would be common between the 33 circuit and the 45 circuit to make them both go wonky at the same time.
Any direction would be appreciated.
We found a beautiful PL-71 at a garage sale for 5 bucks a couple years ago. It fired right up and ran great until last week when both speeds dropped to about half. I have cleaned all pots and switches, re-capped the power supply, control board, and motor (BTW, for anyone else doing this, the values of the motor capacitors are 4 - 4.7uF and 3 - 10uF, since they aren't listed in the service manual).
But this beauty still is running at about half speed. Next step is replacing switches and pots. But could the motor itself be shot? I'm trying to identify what would be common between the 33 circuit and the 45 circuit to make them both go wonky at the same time.
Any direction would be appreciated.