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Vintage turntable running fast, any ideas?

I got a Pioneer Pl-12 turntable from a friend who had it stored away for years. I cleaned it up but have found that some voices have a higher pitch compared to the CD version. I tried the free strobe disks and they verified my fears about the platter turning (I assume) too fast. I also measured similar songs from CDs and albums, and the albums always finish sooner. From some rough time estimates, the turntable is running about 3% too fast.

Looking from the bottom side up on the turntable, there are no adjustments and very little electronics at all. The only electronics are: the motor with a few wires running to it; an enclosed switch to select 115/230 voltable, and a somewhat large capacitor (I think). The "capacitor" has a rating of 0.1 uF and some serial numbers.

I suspect the "capacitor" is old or burnt or whatever. I doubt the voltage switch is the prolem, nor the motor, but who knows?

Any ideas? I have a voltage meter so I can measure the usual volts, ohms, or ampere, but I don't have an oscilloscope to measure frequency.

Thanks for any ideas,
rrick
seandtaylor99
1,262 posts
 
Viridian ... I agree ... to a point ... we're talking a 3% change, not an octave. Personally I'd leave it alone.
rrick OP
23 posts
 
It's wierd, I thought a percent or two change in speed wouldn't make much of a difference, but it does. With the speed-up you get an increase in frequency and also a change in timing. Not only are voices pitched higher, but the music has lots of extra snap to it. If you have a recording that seems dull and lifeless, just speed it up a bit, and man, it'll gain a new life.

Since we like to compare and grade our cables, power cords, and what not, I'll go out on a limb and say the tonal changes from the speed-up is a lot bigger than a cable change. At first I didn't notice the difference so much, but now that I'm keyed onto it, and I notice it immediately.
rrick OP
23 posts
 
The turntable is not perfect but it is much better. From several internet searches I found that the original belt was possibly too thick and a tad long. I had great hopes for a new thinner belt and it did slow down the turntable, but not nearly enough.

The next fix was to get out the emery cloth and start sanding down the brass pulley. The pulley is only 3/8" in diameter, so I didn't have to sand it much, but I did manage to sand it down just a tad too much. (Don't ask me how I managed that, cause I was watching and checking like crazy.)

Luckily, the original belt was still handy and now I have a turntable with two options. I can run it a tad slow or a tad fast. Personally, I like the faster option and don't plan to tempt fate any more.

Cheers,
seandtaylor99
1,262 posts
 
As they say .. if it's only slightly broken, consider whether you want to risk fixing it ! :-0
Glad it worked out. - Sean
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