My Sony loudspeaker suffered some trauma; now the cone makes a "scraping" noise when moved up and down. Help!

I gather you either have hit the cone or else put some huge low frequency pulse into it. (I did this once, dropping a turntable arm onto a record while I had the volume way up. Not good.)

The scraping noise is because the voice coil is no longer on quite the same axis as the coil on the speaker cone. So it's now rubbing. You might try gently try to get it straight. Push on the center of the cone and try to bend or shift it a little one way or the other. Unfortunately, the clearances here are very small, which is why it's so easy to wreck it, so you're as likely to make it worse as you are to make it better.

One of your other respondents mentioned having your speaker "re-coned". He's right, but good luck finding somebody who can do that, and even if you do, it'll cost more than just buying new speakers. So that's what I recommend: If you liked the speakers, just buy another set. And whatever you did to break the old ones, be sure you don't do that again.

Keep the old working speaker for something else. Even keep the broken one; you can get a replacement bare speaker without enclosure from Radio Shack. It won't sound like the original Sony, but it will work.

(I was looking on about.com for a picture of a speaker's guts to make things clearer. I'm sure I found it, but I have dialup access and I wearied of waiting for the page to open.)

The 'speaker needs to be re-coned. You can't do it yourself, it's a specialist job.

wrong connection, try to connect the possitive to the negative vice versa