The third broken DAT deck I bought for parts is a Sony DTC-A6, a later model than the others. It is evidently lower priced, has a mostly plastic mechanism and a simpler electronic circuit. It does have Sony’s Super Bit Mapping, which claims to get equivalent to 20-bit results from 16 bits.

Replaced pin switch

taken from tape load mechanism.

While there isn’t room on the tape load position sense switch board for a larger switch, there is room off board for a microswitch, so a hole was drilled to mount one where it could signal the end of travel for the load cam, and it was wired to the switch PC board.

Replacement switch to sense door open

Switch actuator arm

Sliding cam in door open position

Door closed position sensor pin switch

With all the position sensor switches working, all that remained was to clean or replace brake pads, adjust holdback tension, and deal with a broken takeup reel brake lever which provides holdback tension in reverse play. I was able to glue a felt pad to another lever so it rested against the brake drum in reverse play just enough to keep tape moving without slack. It plays well enough in reverse to seek tracks, but not well enough to play a whole song backwards.

I was sort of hoping this machine could be a parts donor for the two fancier Sonys, but there are no interchangeable parts. The head drum is different, as are pinch roller, switches, and electronics. Now that it’s fixed up, it works and sounds fine, but the plastic chassis just doesn’t inspire the confidence of a metal chassis.

Sony was the only company who made more than minor changes to their DAT machines over their production life span, and they made different mechanisms for portable DAT Walkmans, home stereos, and computer data storage. The best mechanisms were from the computer division. They were less complex, had individual motors for each reel, head drum, tape threading, and cassette loading, and also had 4 heads so they could monitor off tape for errors while recording. The simplicity makes them reliable and they don’t depend on felt pads and springs for tape tension. Alas, audio recorders weren’t built with those mechanisms. Even the professional broadcast models were simply consumer models painted grey and fitted with balanced XLR inputs and outputs, and in some cases added circuitry for time code sync to video. Data recorders cannot play audio tapes and vice versa. The formats are different on tape, and neither recognizes the other as valid. A few decks were made for Silicon Graphics which could handle both, but they are rare and expensive when they show up for sale.