REPAIRING AUDIO CASSETTES 6-17-07
REPAIRING AUDIO CASSETTES latest updates and/or corrections 6-17-07 First of all, don't force anything... it will just chew up the tape. Lets start with the worst case: a reel that will not turn. Examine the cassette and see if the tape is somehow snarled and jamming the reel. If so, you will probably have to open it up to find out what happened and hopefully, fix it. If the shell has screws holding it together... it's easy to get it open. If it has no obvious screws, it's probably glued together. You can still open it if you're careful, but you may have to transfer the tape to another shell if the original is broken by forcing it open. Make notes of the position and location of the tiny parts inside as you work! If it's an important tape you're trying to save, first open another one for practice. At some point, you'll want to turn the reels to advance the tape one way or the other. You can make a tool that fits the reel hubs from a pencil wrapped with enough Scotch tape to give it a snug fit. Cassettes are made up of two half-shells. To open a glued shell, take a small knife and find a spot in the case along the seam that the knife edge can penetrate. Normally the front of the cassette (careful of the tape) provides such a starting point. While prying slightly with the knife, tap around the edges of the shell with the handle of a small screwdriver. As you work the knife forward, tap just ahead of it to crack the seal. Don't force it or the plastic will crack sideways instead of along the seal. Keep working forward until you get the shell open. If you get stuck in one spot, try working the other direction. The combination of applying force with the knife edge while smacking the case at the seam will open it all the way around. Once it's open and you correct the problems, you can put it back together and glue it in a few spots with a -tiny- amount of super glue or plastic cement. CAUTION: super glue tends to wick it's way -everywhere- and will get on the tape if you're not careful! It's best to only apply the glue to the sides and rear of the shell... stay away from the front. Use small strips of Scotch tape to hold the shell together until the glue sets up, or use the tape alone to hold the shell together long enough to copy the tape over to a new one. If you use superglue, as a precaution, make sure the tape is wound all the way to one end so if any glue does get on it, it's only on the leader and not the tape. With regards a cassette that is just "sticky" or sluggish... the most common reason is that the tape is unevenly packed. You can see that by looking at it. The reel pack will look bumpy, not smooth. Sometimes you can free it up by rapping it flat against a table top, first on one side, then the other. When it starts turning more freely, stick it in a player and wind it to the end, then back all the way to the beginning to repack it. It should then work normally again. Note that some machines will shut down while playing or winding "sticky" tapes because it requires too much torque from the machine. The player thinks it is seeing "end of tape" and shuts off. Cassette tapes are most difficult to splice because they're so small. If the tape is damaged, you may have no choice but to edit out the bad area. Be aware that audio tapes are not as critical as video tapes as far as wrinkles going over the heads. If intact (not badly stretched or torn), even if badly wrinkled, leave it alone... it should still play although the sound may be a bit muffled. If the tape is torn, broken or stretched so badly it will not play, try to find some splicing tape (Radio Shack has a kit with tape and a splicing block in it) to do the job correctly. If you only want it to last long enough to dub it over, go ahead and use scotch tape. Trim the broken tape ends if necessary to make a neat splice. Do not overlap the ends, but rather butt them close together and put the tape over the two ends on the back side of the tape (so it will face away from the heads in the machine). If you're not using a splicing block, make sure the tape is straight when the splice is done. If it's crooked, it will skew in the machine and may be damaged further. Redo the splice if necessary until you get it right. Use tweezers to hold the tape so you can cut off the excess splicing tape with scissors. If the splice is too wide, it may stick in the guides of the player. One other common problem with "bad" tapes is the infamous "half twist". When playing such a tape, you may suddenly find the voices muffled and playing backwards. If there is a half twist in your tape, there is another one in there somewhere! The tape must be pulled out and rewound by hand until the second twist is found.... not fun! A full twist means that the tape has somehow jumped over one of the reels. The cassette will have to be pulled apart and the reel flipped over to correct it. As an alternative, run it to the end (by hand) and redo the end splice to the leader. It's a slow and tedious process, but I've done it. I repair audio tapes (talking books) for the local library. Ray Carlsen CARLSEN ELECTRONICS... a leader in trailing-edge technology.