Portable cassette player recording mystery

I am trying to use a portable cassette player to play tapes and record them on my pc. I can play tapes on the tape player and listen to them on headphones plugged directly into it with no problem. When I plug the player into my line-in on my pc, all I can record or hear on my pc is spurts of low distortion every once in a while. I can only get the sound if I turn the levels all the way up. So I thought the problem was with my pc so I used an old phone with a headphone jack and plugged it into the same line-in. I was able to hear and record from the phone no problem. So why do I have this problem with the tape player with my pc?
 
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So I thought the problem was with my pc so I used an old phone with a headphone jack and plugged it into the same line-in. I was able to hear and record from the phone no problem. So why do I have this problem with the tape player with my pc?
Is it the same lead?

Is the output of the cassette player at zero volts DC ? Check by measurement on the output of the lead when it is connected. Maybe the player needs a load impedance of some sort.
 
Thanks for the replies.
Is the portable cassette player on batteries, or on mains? If the latter can you try with batteries and mains unplugged?
It can only run on 2 aa batteries. No plug in power.
Is it the same lead?

Is the output of the cassette player at zero volts DC ? Check by measurement on the output of the lead when it is connected. Maybe the player needs a load impedance of some sort.
Yes, same line-in to the pc. When the tape player is playing I get -2.5 VDC on both channels. When it's stopped, about -0.5 VDC.
Have you tried to connect headphone output into pc?
Yes, that's what I tried first.
 
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Yes, same line-in to the pc. When the tape player is playing I get -2.5 VDC on both channels. When it's stopped, about -0.5 VDC.
Any line level input normally expects to see zero volts DC (no DC offset). I suspect this is the cause of the problem. You can try adding something like a 22 ohm (not critical, use what you have) as a load on the players output.
 
Funny, was just thinking about this for another thread. It's cosmic, man. Audio inputs to computers and lots of other widgets really expect an electret microphone with internal NJFET buffer, and power the open-drain buffer with 2.5VDC down the signal wiring. Could be that your tape player was complaining about that.

All good fortune,
Chris