My Jensen JTA 450 is playing LPs too slow even though 33RPM is already set. The songs are slower than usual. Please help me.

Could be the belt for the pulleys is stretched a little, or there is something making it slip, or the potentiometers were set incorrectly from the factory . It is normal to have one for each speed. It is unknown if you can access these from the bottom of the unit. Slippage is less likely to be caused by something oily, since it would alternate the speed faster and slower and yours seems to have worked then reached a constant slower speed. Do your 45's and 78's play ok? (yeah I know, does anyone have a lot of 78's on hand)
Your model does not have an outside pitch control to fine tune the speed faster or slower. Another Jensen model JTA-230 does. Entry level turntables such as yours are not speed accurate reliable. After reading reviews on your turntable, it's possible that the belt is the problem. If the slow speed problem had happened from the start, it would be safe to say that the speed wasn't calibrated correctly and you could have returned it and perhaps had better luck with another one but because it worked fine at the start and then now plays slower, it's either the belt or the potentiometer for the 33rpm speed has somehow changed.

Jody, the arm the needle is on, usually adjustable with a dial on the end that can lighten, or put more weight on needle to help it track better on records. Other then that, the belts normally are changed to address slow speed issues. Check the attached links,instruction and guides, Good luck
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Jensen JTA 220 Instruction Manual Page 2

http://audio.manualsonline.com/manuals/mfg/jensen/jta220.html

How To Calibrate Your Turntable For the Best Possible Sound

How to Adjust Tracking Force

Do you have a switch to select the size of the record as well? We had a record player that could play 7" singles at 33rpm (floppy vinyls given away by Sunday papers). We had to select 33rpm and also 7" on a separate lever for this to work.

If the 45's play OK then your belt might not be fitted in the right place. If they are both slow, then either the belt is slack or the drive is faulty.

Check the RPM switch on the turntable is on the correct speed for the record you want to play. Otherwise it could be a belt problem internally.

Yes, it can. Just connect the RCA LINE OUT from it to the Line IN from the pc with a cable like
http://www.amazon.com/Dayton-3-5RCA-12-3-5mm-Stereo-Cable/dp/B000F7P7EW
Then to pick up the sound just use any recording program you want. I use
http://www.roemersoftware.com/free-sound-recorder.html

Hello the turn table has two speeds. 45rpm and 33rpm (rotations per minute) If you are playing a record that takes up the entire turntable you need to set it on 33rpm. For the records that only take up half of the turntable you want to set it on 45rpm. Setting the turntable on the wrong setting for a certain size record can make the record play to fast of to slow.

Try moving the arm up to the end of the vinyl, if it does go till the end of the vinyl then try adjusting your counter weights, a penny will do, if it doesn't go till the end of your vinyl then there's a mechanical problem check any obstruction at the botton of your arm.

your player has the firmware of share type which uses it for your pc so load only 150 songs

I removed the turntable belt and reinstalled it. Now, the 33rpm albums turn at the speed they should. Thanks