Pioneer PL-7 (mid-60's) Motor start capacitor help, please.

[JK-47]

Hello, I'm a new member. I recently took in what appears to be a very early Pioneer PL7, The tone arm is an unusual replacement. There is no model number on it. As a whole it seems to be extremely clean and restorable. The problem, is the motor. When switched on, the motor has a slight vibration, but isn't spinning. I'm assuming the capacitors are dead, as the motor start cap is dated 1964, With turntables, I am very good with the mechanical repairs. I have a huge large collection. I can do basic capacitor replacement, I don't have the electrical expertise to figure out a replacement for this big, long discontinued motor start cap. I've recapped many crossovers, and turntables, but hadn't come across this type of capacitor.

I found the this thread in the forum, and noticed a similar PL-7 with what looks like new capacitors for the motor/power. Mfrench's post on page 3.

https://audiokarma.org/forums/index...6a-finally-after-years-of-wanting-one.686665/

I was hoping one of the more seasoned members could give me some advice on how to build a motor start capacitor that will get this guy running again.

 

[ralphfcooke]

Beautiful old turntable! You're probably right about the capacitor. You're very unlikely to find an identical replacement, but you don't need one.
The pl-7 was originally configured to allow the motor to run most smoothly on either 50 or 60HZ, by switching in the second, smaller capacitor
as well as the larger. I attach a diagram below to show how it was done.
This was of limited use, as, though it provided the correct capacitance you would still need to swap out the pulley to match the frequency to the required speed.
If you are in the US (or anywhere else that runs on 60 HZ), then you only need a 1.5uF capacitor rated at 250V.
If you are on 50HZ then you need either a 1.5 and a 0.3uF cap and wire them in as the existing ones are, or you could simply use a 1.8uF cap.



The second, smaller capacitor (0.05uF) is wired across the switch in order to suppress pops when power is turned on an off
Just as an aside, it's especially impressive that there's an oil feed for both the upper and lower bearings!

 

[JK-47]

Thanks Ralphcooke, That helps quite a bit. Mfrench sent me some detail photos of his, and the way he replaced that motor start cap. I have a few options now. This is a great forum!!

 

[JK-47]

I meant to upload photos months ago, but the weeks are like days this year. It's nowhere as neat as Mfrench's solution, but it works all the same.

 

[mfrench]

Good on you! Great work.
And welcome to this side of the forum. These are really nice decks.