Common Failures of Digital Tape Machines
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A SPIKED JOINT

What exactly is a “cold” solder joint? Prior to soldering, most components are “stuck” to the printed circuit board (PCB) by their legs, which are also called “leads.” The PCB is “wave soldered,” a process that electrically bonds the joint where the lead meets its designated PCB “pad.” The primary problem associated with this process is the consistency of the soldered connections across the board.
Big, heavy transistors need more solder than resistors, capacitors or ICs. In addition, transistors, connectors, pots and switches too often rely solely on the solder for physical support as well as the electrical connection. The PCB design, its temperature presoldering and the solder temperature must be just right so that all connections are well-made (shiny, not crystallized). Enough time must be allowed post-soldering before the board “travels,” because vibrations can corrupt solder that has not yet fully cooled. Post-manufacture temperature changes, vibration and “road use” will all conspire to weaken the vulnerable joints until the connection becomes intermittent. This is especially true of the “wear items,” especially connectors and heavy parts like TO-220-style power transistors.
—Eddie Ciletti

THE MANIACAL MECHANISM
It is not my intention to suggest that users go much further than popping the cover and cleaning the heads. Head cleaning is not a panacea but just the first suggestion from customer support and your local technician. You should know at least that much and have some familiarity with what “normal” is. As described in January and in more detail at www.tangible-technology.com, learning to access the Error Rate display is the very best preventive medicine. As we come to rely more heavily on CD-Rs, I encourage users to contact manufacturers, coercing them to include an Error Rate display as part of the feature set.

If you are a geek in training, then let me recommend WIHA screwdrivers, available from my friendly competitor Paul Plotnick at Pro Digital at www.prodigitalinc.com. You can’t have enough tools, and these are the best screwdrivers I’ve found yet.

WHERE THE RUBBER MEETS THE ROAD
Okay, enough about heads and tape. Let’s look at some of the other problems that often plague digital cassette recorders. I am not obsessed with changing pinch rollers unless they are really glazed, but the capstan shaft should be scrutinized carefully, especially on a DAT recorder where tolerances are critical. While they are not at all easy to clean, I’ve seen DAT capstans coated in a thick, black funk (except for a 4mm swath where the tape travels). This muck can lift the pinch roller away from the capstan enough to alter the tape path—reverse-play is a challenge for every recorder, even on its best days.

COLD BLOODED
In my first Mix column (April 2000), I trounced the myth that Sony and Panasonic machines are aligned to a different standard. Older Sony DAT recorders are more likely to make out spec tapes, yet they are also more tolerant of the same. Panasonic decks hold their alignment better but are less tolerant of poorly recorded tapes.

Most Sony recorders have fewer moving parts, because separate reel motors simplify and replace numerous wear-item parts, such as clutches, gears or pulleys, that transfer motion from the capstan motor to the reel tables. Pioneer and some Alps transports have the aforementioned wear-item parts, as does Panasonic, the DAT machine most likely to jam.

While most DAT problems are mechanical, many Sony recorders, for example, slowly fail from cold solder joints. (Some of the most technologically advanced manufacturers use consumer-grade construction techniques that compromise their most innovative designs.) Poor soldering can cause frustrating intermittence that ultimately enrages users to do damage to the more vulnerable “accessories,” such as the loading mechanism.

While the Sony PCM-R500 is a favorite in its price class, it also has the most vulnerable loading mechanism of all DAT decks save for microportables. At the first sign of intermittent behavior, it’s best to repair “simple” problems before more serious damage is done. Have a professional closely inspect the soldering at all connectors and power transistors.

MORE FEEDBACK
Current tape-based systems that started life in the 16-bit world have been expanded to their limit—either more bits or more samples but not both. Disc-based systems will permit higher sample rates and bit depths together, putting more emphasis on the quality of interconnections, cables, transmitters and receivers—all the more reason to include data integrity indication of the incoming signals, as well as the media, on all products.

As with error rate, knowing the “quality factor” of the arriving signal can either inspire confidence or initiate the investigation process. Better signal quality (from tape, disc or cable) improves the data recovery “headroom” and ultimately the quality and consistency of the sound. With-out it, all the king’s horses and all the king’s men will not be able to reassemble a digitized Humpty Dumpty.

Eddie Ciletti can be reached at his Web site at www.tangible-technology.com.

Reprinted with permission from

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