*** this instructable takes into account that you have some mechanical dexterity and some experience in disassembling consumer electronics ***
lalala music music KERCHUNK!
the lowly 8-track tape, abandoned long ago in favor of the cassette tape. they can still be easily found at thrift stores and flea markets for less than the cost of a snickers bar.
the 8-track was the first portable music medium that actually really took off. sure there were other portable formats but the 8-track was the first to win wide public acceptance and become a common option in automobiles of the 60's-70's. initially created by lear jet, the aircraft folks, the 8-track became popular due to its simplicity of use. 8-track tape machines found there way into portables, cars, and home stereo.
shove the tape in and the machine starts playing. you have 4 "programs" to choose from. they are musical programs and have nothing to do with computers. each program contains stereo songs. 4 programs each having 2 tracks since they are in stereo = 8 tracks.
let's learn a little bit about these tapes and how to revive a malfunctioning machine!
Step 1: how the tape works
the 8-track tape is a continuous loop tape so there is no rewind. the only options the consumer has is play, fast forward, record, and program change. some basic machines like the one featured in this instructable only offer play and program change.
the picture shows how the tape works. the tape is pulled from the center, out past the machine's mechanism, and then re-spools onto itself on the outside of the spool. the action of the tape being pulled from the center causes the spool to turn thus winding the tape back onto itself. what makes this work is that the backside of the tape, the side that doesn't have the music on it, is polished up with a dry lubricant to aid it in sliding out and over the spool of tape.
unlike most tape formats, the rubber roller called the pinch roller is part of the tape cartridge and not the machine. in the picture you will see the roller on the top right, the playback head in top center, and top left you will see what looks like two "J's" back to back. that is the sensing contact that causes the machine to automatically change programs as the tape is playing.
the tape has a foil splice in it. when the foil hits the contacts it trips the program change circuit causing the playback head to shift to the next program. changing programs can be left to the machine to do it automatically or you can hit the program change button and do it yourself during tape play.
the tape was divided up into 4 programs each equal length. this meant that songs had to be picked to equally fit into each program or you just let it ride and your music got interrupted by a KERCHUNK during the song as the machine changed programs. that's one of the endearing yet annoying quirks of the 8-track format.