a while ago i picked up this old DAT drive for a very good price. let's see if i can get it working! 
it is the Mitsumi DK4-SS4001, a SCSI DAT drive.
took out a bunch of screws and now we're in! DAT drives use a helical scanning system just like an old VCR, but in miniature. the round thing in the middle is the rotating head.
i powered it up but it refuses the accept the tape for some reason. like a VCR, it is supposed to pull the cartridge in, extract the tape, and wrap it around the rotating head.
the middle LED is solid yellow, and the left and right LEDs are blinking yellow. i think this is some sort of error state.
disassembling it further, i noticed that it has a 68K CPU inside!
there are lots of flex circuits. my suspicion is that there is a bad/dirty sensor inside which confuses the firmware into thinking that the tape is already loaded and in position.
here's a position sensor. this one indicates if a tape has been pulled in or not
driving the motor directly, the mechanism itself seems to work
it's a pretty clever design. I figured out how it goes together. first you start with the metal base
then the circuit board drops in. there are metal tabs that fit into holes in the PCB.
this piece of metal goes in next. it has these spring tabs that apply downward pressure to the PCB--the metal case acts as a heat sink, and pressure ensures good contact with the chips.
finally the mechanism drops in. there's a big connector that goes between the logic board and the mechanism that carries all the signals.
the whole thing is held together with the two screws on the left.
it works! the problem? I had the current limit set too low on the 12V supply.
it even ejects the tape.
this tiny foam wheel is supposed to pop out and whisk dirt off of the spinning head. unfortunately the foam is crumbling.
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