Could be low supply, a dead motor drive transistor or some other issue with speed control. Sounds like semiconductor failure in any case. Some meditating over service docs and poking around with a multimeter will be needed.
New to this site and found it by Googling Pioneer PL71 restoration. I purchased one of the 1st consumer units available as I had possession of this one before the stores I visited had theirs. I still have it along with a Shure V15 type II. There is not a scratch on the turntable but there is a problem with it. After sitting several years unused the strobe shows it to be rotating too slowly and with the adj. turned all the way it is still slow. Is this something that can be remedied or do I play taps and buy another table? I'd love to use it again if possible. Also, would the cost exceed the value of the table?
I'd say you have a 95% chance all that is needed is some basic maintenance:
Clean the speed control potentiometers and switches with a good contact cleaner / deoxidizer like Caig Deoxit D5 ... followed with lubrication with Caig Faderlube F5. That will probably bring operation of the speed controls back within range. You might have to adjust the speed trimpots on the motor control board as well. Pictures of the components are in this thread. Check vinylengine.com for copies of the service manual and check audiokarma.org for a sticky on using Deoxit (Idiot's Guide to Using Deoxit). I'm sure there are threads here as well to help guide you on that.
My PL-71 was only with me for a short time. For some reason I keep wondering about ... I sold it and the Shure V15III that came with it (which by itself covered the cost of the turntable!). Nice table. Nice arm. Love the wood veneer plinth as opposed to the vinyl covering on so many of Pioneer's offerings. Liked the VTA adjustment on the arm.
Clean the speed control potentiometers and switches with a good contact cleaner / deoxidizer like Caig Deoxit D5 ... followed with lubrication with Caig Faderlube F5. That will probably bring operation of the speed controls back within range. You might have to adjust the speed trimpots on the motor control board as well. Pictures of the components are in this thread. Check vinylengine.com for copies of the service manual and check audiokarma.org for a sticky on using Deoxit (Idiot's Guide to Using Deoxit). I'm sure there are threads here as well to help guide you on that.
My PL-71 was only with me for a short time. For some reason I keep wondering about ... I sold it and the Shure V15III that came with it (which by itself covered the cost of the turntable!). Nice table. Nice arm. Love the wood veneer plinth as opposed to the vinyl covering on so many of Pioneer's offerings. Liked the VTA adjustment on the arm.
Yes there are, but I need a picture of the other side of the motor circuit board, which is not shown in this thread. Understand?
Thank you for your quick reply. I've had several inquiries about making turntable Isolation upgrade feet for them. In my research, the Pioneer PL-51 and PL-55x share the same bottom cover design, so I can cover those models as well.
That is worth look at for sure, feet seem to make a very large difference on all turntables. Looking forward to hearing about your findings. I can wholeheartedly recommend Isonoes for the SL-1200, it’s not a subtle improvement.
But I have also had outstanding success with simple Vibrapods, and at the cost, is worth trying on any table.
But I have also had outstanding success with simple Vibrapods, and at the cost, is worth trying on any table.
Will do. I will use large sorbothane isolator in my turntable feet. Currently working on Height adjustable Isolation foot
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@6L6 I have a PL-71 I've been running a few years and like a lot. I had to replace the 33 rpm micro switch as it was not holding speed. It is much better now, but has some noticeable speed variation as I watch the strobe. I am planning a recap of the power supply and motor, and saw your suggestion of replacing the Zener with a TL431. Is that a drop in replacement, or do I need to change up some other parts and values as well?
Also, @MonsterMawd I installed a set of your feet and they did wonders decoupling the turntable form the floor and cabinet. Thank you!
Also, @MonsterMawd I installed a set of your feet and they did wonders decoupling the turntable form the floor and cabinet. Thank you!
It wouldn’t be a drop-in, and it likely wouldn’t make very much difference in that circuit. Just get a fresh zener if you want to make a change.
The re-cap will absolutely be beneficial. Make sure you clean the pots and switches as well, it’s all part of the LC tank that makes the speed reference.
They are great tables, well worth the effort restoring.
The re-cap will absolutely be beneficial. Make sure you clean the pots and switches as well, it’s all part of the LC tank that makes the speed reference.
They are great tables, well worth the effort restoring.
Recap is complete! Borge the power supply board and the motor. Speed stability is much improved, but not rock solid yet. Still just a bit of fluctuation when I watch the strobe.
I replaced the micro switches when I acquired the turntable 4 years ago just to have any usable speed stability at all. Would the next step be to replace the speed control pots? Or am I chasing problems that exist outside of my control?
I replaced the micro switches when I acquired the turntable 4 years ago just to have any usable speed stability at all. Would the next step be to replace the speed control pots? Or am I chasing problems that exist outside of my control?