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 Maintenance Key Title


If you've been in the industry for more than ten years, you can appreciate how far the medium has progressed. As we have advanced ourselves, the manufacturers have advanced us with the absolute miracles of technology. But sometimes, with those miracles, there comes a learning curve.

It has been discovered that metal tape use vs. oxide product will double the life of tape heads. This good news also comes with some not-so-good news.

A compound that may be a product or by-product of the lubrication used to facilitate metal tape travel "slippage" has been thought to be the cause of a situation similar to a head clog on small format camcorders. Identified by Roger Macie, of Dedham, MA, as "baked-on" residue, this situation has caused "clog-type" characteristics that do not disappear with standard cleaning methods.

This advisory is not a cause for alarm as much as a call for facility maintenance people to learn a different regimen for maintenance of the SDH series (small head diameter) VCRs. Microscopic observation of the head followed by cautious use of a head-cleaning cassette is recommended for dealing with this situation. Be cautious, however. The tip penetration of the smaller diameter heads and expense of head replacement mandates more than casual use of an abrasive head cleaning cassette. If you don't know, leave it to a pro. Your head is a terrible thing to waste.

Macie's Find

Roger Macie, a veteran maintenance technician, recently gave notice to Ikegami and Sony that he was seeing a consistent pattern of a compound amassing on the heads of SDH series machines.

Macie discovered the characteristic during a microscopic examination of the heads that were performing consistent to a VCR with a clogged head, even after a rigorous cleaning.

"Clients were coming in with badly recorded tapes with one or two heads apparently clogged," Macie says. "Their original perception was a chroma breakup, of sorts, that I came to see as that, and a distortion in the RF envelope."

Conventional cleaning methods such as head cleaner and/or alcohol and a clean wipe are not effective in removing the compound.

"The only way I could effectively clean this compound off the head was to use an abrasive cleaning tape," Macie adds. "Even then, some heads do not clean off enough to totally eliminate the marks I saw under the microscope, and warrant a second or third 5-second pass with the cleaning tapes: the stuff was really on there!"

One thing that may be a bit scary about this characteristic is that there is not always an RF warning when there is a "baking" condition. There is not a large deficiency of RF, which is the keying point of RF warning signals. There is, however, distortion of RF envelope that will similarly distort your video.

Manufacturers Response

Tom Calabro, Executive VP and Director of Engineering for Ikegami, US, is aware of Roger's discovery, and expressed confidence that proper maintenance was the key.

This is certainly something that has to be dealt with. "It's a minor disadvantage, but can be dealt with by performing proper maintenance, just like changing belts. Those cleaning tapes that you used to keep on the shelf? You'll need to use them now."

Dan Smith, Senior Technical Services Representative from Sony's Alabama Media Plant, is also familiar with the challenge of the "baked-on" compound.

"The drum spins faster in the (SDH) product. And the contour of the surface of the tape is different. These factors alone may lead to a situation that warrants a more frequent cleaning of the heads," he says. "We are always looking to change or modify our products to make them better, and perhaps a cleaning every 40 to 50 hours with one of our micro-abrasive cleaning cassettes is a characteristic of a newer more superior technology.

Reinforcing Smith's opinion, a bulletin from Sony Electronics Recording Media Productions Group says the following: "In order to remove this build up, Sony recommends a complete cleaning every 20 hours of tape time. Sony also recommends that a head-cleaning cassette be used every second cleaning (40-50 hours) FOR ONLY FIVE SECONDS." Sony has also issued a service bulletin for this "build-up" characteristic.

Roger has had different experiences with different build ups, and has had to run an abrasive tape for as long as 60 seconds to remove excess mass on some heads. This long time period is not recommended without simultaneous microscopic monitoring. Leave it to a pro with the tools Macie states: "Checking the CTDM (compressed time division multiplex) signal while playing back the last 15 or 20 seconds of a recorded tape is (an accurate status indicator}. Any distortion, or breakup, in this signal would warrant cause for concern, and perhaps some cleaning on the spot. It is essential that the last 15 seconds be played back, and not too much less, as you can also control track discrepancies, another symptom of the condition. These are not always apparent with a quicker playback of 5 seconds for instance.

What's the saying? "There is no such thing as a free lunch." Here we have this great gear that'll do it all with such nice quality, but it's not free. We are saving money on one hand, but having to spend some of the savings on maintenance. This "baking" characteristic, while not apparent on CDH VCRs, is as much a part of the state-of-the-art SDH VCRs as FM audio. If you are getting the highest quality out of the product and saving the head wear via metal recording media, you'll also have to change your habits and perform frequent cleaning.

A thought worth some merit is to use an SDH camcorder with a separate CDH series VCR for location production shoots when the characteristics of such work allow for the larger package. This lessens the chance of the "keeper" being affected by the baking phenomenon.

Other principles of consideration have pointed toward tape storage. Sony Corporations Recording Media Products Group published a comprehensive advisory in January of 1991. MPG Technical Report Volume 6 can educate the reader on "Archival Stability." The report is very well written and details and not-so technical points.

The MPG Tech report, obviously, would not be able to address newer series of tapes like the BCT-D, BCT-Ma, and UVWT-Ma tapes which are superior to those of previous years. Sony and other manufacturers will continue to improve their technology, and it is certain, as long as we are in a technology that depends on heads and tapes, we will encounter the effects inherent to the techniques.

John Matarazzo, National Technical Services Manager for Sony's Recording Media Group agrees. "Improvements in lubricants and binding systems produce conditions that will improve the vulnerability of tape."

Being more specific, Matarazzo says, "The new BCT-Ma series has improved cross-linking (mechanical composition) and has systems that contribute to a reduction in surface debris."

It's an age of new technologies that require different methods of performance and maintenance than the technologies of the past. Field color shifts, multi-frame distortions and repetitive dropouts do not necessarily indicate situations that warrant extensive repair. The cause might be from manageable characteristics that warrant attention by different methods of, and more frequent, cleanings.

Joseph Tibensky, Director of Marketing for the Recording Media Products Group, adds, "During the normal evolution of any product, we try to make as many improvements as possible. Sony BCT-Ma series between Betacam SP cassettes, which have now been on the market for two full years, feature improved runnability, cleanliness and durability beyond that of the previous BCT-M series. Since the introduction of this formulation, and that of the similar Broadcast Master formulation for D-2 cassettes and HMPX Hi8 formulation two years ago, the Sony Professional Media Division has been enjoying the highest level of professional video cassette product reliability in our history."


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