TASCAM DA-302 DAT
TASCAM DA-302 Dual DAT Deck
Wednesday, November 22, 2017
While browsing Craigslist I saw an ad for three DAT machines, not working, for parts, for $35. Since I was working on my own Sony DATs, these looked like a good source of parts and learning how to fix rotating head recorders. There were two Sonys, a DTC-A6 and a DTC-75ES (which is a high-$$$$ version of my DTC-700), and a TASCAM DA-302. I’ve done maintenance on my DTC-700 over the years, so I’m somewhat familiar with Sony circuits. I looked at them first. The Sonys at least lit up and would respond to button presses, tho neither would load a tape and play it. The TASCAM was totally dead. No lights, no response. The tape mechanisms were loose inside the chassis, flopping around on their wiring.
Having gone as deep as I could into each of the Sonys and come to a brick wall (missing parts), I decided to pop the TASCAM open and poke around. The totally dead bit was a 7805 regulator whose leads had all come unsoldered due to heat cycling. It fell out when I loosened the screw holding it to the heat sink. Soldered it back in. Then the front panel lit up, but was showing errors. I knew from watching “12voltvids” on Youtube hack into a TEAC that there were small belts that went bad and you could order them from TASCAM for $9.99 + $20 postage and handling apiece. (No way.) The previous owner had stuck a couple of meaty O-rings in there which the motor wasn’t able to spin, so I cut the O-rings in half with scissors (don’t ask…) and got one deck to play, sort of. Promising! So next, look inside the head preamplifier and RF section. Hey, it’s the same Sony chip and circuit I’ve already sussed out! So remove all the electrolytics and replace with nice new solid tantalums. In fact, all the DATs I’ve seen use parts of the Sony chip set. And so on, one symptom after another ‘till one deck is playing. Repeat for deck #2. No go. Go back and tidy up the recap job. Now it plays, but won’t rewind. Hmmm…. that took all afternoon disassembling the deck until I understood how it’s SUPPOSED to work, and carefully re-shaped a metal plate that someone had “straightened”. Now both decks play, record, FF, and RW. Then comes the real test, get out the Windex, clean and shine it up, and button it up, and see if it still works. Murphy’s Law says that a newly repaired machine will run until you put all the covers on and install it in a rack, but this one passed the final test.
Check out this video for a look at TASCAM’s DAT mechanism.
https://www.youtube.com/watch?v=E7u7fLsgSeM
The tiny rubber belts can be replaced with little clear silicone bands for girls’ pony tail hairdos from Walgreens. Pack of 150 for $2.20. I also got a pack of 500 multicolored Scunchies (more pony tail rubber bands), but the Scunchies don’t fit as well. 500 of those for $4.
The most unusual of the DAT machines I bought off Craigslist is a TASCAM with dual tape mechanisms. It can dub tapes or record or play two tapes in sequence.
The control panel has a number of unique features related to controlling the two decks. The Common Mode switch sets both decks to operate simultaneously, as in making a master tape and a back-up tape at once (1&2). The 1->2 setting causes deck 1 to record or play first and when it reaches the end of tape, deck 2 takes over. The OFF position lets the decks operate independently, except that there is only one set of inputs, so you can’t record two different programs at once.
In DUB MODE, the DA-302 can copy from DAT1 to DAT2 either at normal or double speed. The deck controls are slaved together so you only need to press one button. Up to 10 DA-302s can be slaved together to duplicate tapes. It’s a unique and versatile machine which was popular with Grateful Dead tape collectors for copying DATs to trade with fellow tapers.
Since the Youtube video linked above shows the repair process pretty well, and how to replace the belt which by now is bad on nearly all of these TASCAM decks, I won’t go over that here. All models of TASCAM and a few other brands used this same tape transport which was made by Alps. It’s pretty reliable except for that belt. If someone has been messing around and bent or misadjusted any DAT mechanism, it can be very time-consuming to get it working properly again.
Replacing belts and cleaning the tape path with alcohol will often get one working again. Be careful cleaning the head drum. Use a chamois or some cloth that won’t leave fibers on the heads. The heads are sharp-edged ferrite material, and are brittle. Put pressure only in the direction of drum rotation. Up or down wiping can snap a head off. If you don’t have a proper chamois cleaning stick, a dry piece of typing paper held against the head as the drum is rotated will clean it fairly well.
The most critical adjustment is the height of the guides next to the head drum. You need an oscilloscope to adjust these. Leave them alone unless you have a manual and proper equipment, because you can’t really get it right “by ear”. The manuals for most of these obsolete machines can be found online, and a read-through of the alignment procedure before beginning will save time in the end unless you’re an old hand at fixing these.
When it came back to life, this machine showed zero hours on the heads. It looks pretty well thrashed, so I can’t guess how many hours are really on it. The manuals say head drums should be replaced every 1000 hours, but I haven’t yet seen a worn-out head, and some have thousands of hours on them. That’s good because parts for these machines are no longer made, and head drums are model-specific. A drum from another model won’t fit. If parts are needed, they have to come from a spare machine, or you have to make them.
The electronic parts of a DAT machine are usually OK except for the surface mount aluminum electrolytic capacitors, which are as bad as the ones in computers from the same era. You can figure on at least partially recapping most DATs these days. The A-D and D-A converters in most DATs are excellent. The troublesome bits are due to the complex, tiny, and delicate tape mechanism. Recording to a flash memory chip has replaced tape today. Today’s recorders ought to last longer than these, but they don’t necessarily sound any better.
They might fit other eject mechanisms in DVD players, etc. I thought I might have to visit a dentist to get some tiny rubber bands, but the women’s hair style counter has the solution. It turns out the hair bands are thin enough to stretch if the mechanism is changing gears a lot. Putting two of the bands on at once cures that.
They’re so thin that 3 or more could fit into the groove of the pulleys.
While you’re there, pick up some elastic bands for your shock mounts, too.
