How can I minimize head wear ?

DAT heads wear out at different rates, depending on their design, the type of tape being used and the way they are maintained and used. Some machines like the SV-3700 keep the tape loaded and head spinning when in the stop mode. It takes 12 hours to unload the tape from the head and turn the head motor off. This is done in professional machines to improve start up time during playback and record. These pro designs will wear out heads faster, if tapes are left in the machine. In this case using the machine properly will reduce head wear. Head cleaning is also very important. We see a lot of heads that are not worn out, fail. This is because they have not been cleaned properly or 90 meter DDS tape is being used. The oxide has been on the head so long that it becomes glazed onto the head or magnetic particles have clogged the head gap. While dry cleaning tapes are slightly abrasive, under cleaning a head is worse than not cleaning them enough. A regular cleaning program will extend the life of the heads. Using 90 meter or longer DDS tape is also a contributing factor in head life. The thinner tape is more likely to stretch, allowing the oxide coating to deposit on the head assembly. If you use 90 meter tape, clean your heads often and keep your machine as cool as possible. Tapes should not be hot to the touch when removed from a DAT machine. The older Sony heads used in the DTC-1000ES, the older model D3, D10PRO and 75ES all have a very small space between the upper drum and the lower cylinder assembly . The Panasonic and all Tascam machines (except the DA20) use this type of design. Most of the newer Sony machines, the Tascam DA20 and Fostex D5 use a different head design. They have a large space between the upper and lower cylinder. This large space type of head wears the fastest and is not capable of floating the tape on air over the head. The older Sony heads almost never failed due to the use of an air bubble to "float" the tape and minimize head wear. One Sony engineer told us they expected a life of 5000 hours on this design. The large gap heads also have less surface area for the tape to contact, therefore what area there is wears faster. The lack of surface support for the tape allows for deeper penetration of the tape by the heads mounted on the upper drum. I believe this also effects tape life. This is what I have observed on the DA20, Fostex D5, newer D3's, all D7/8's and the Sony 59es, 60es, 670, 690, 790 , A7 etc. The Panasonic, most Tascam and the hi-end Sony machines use the small space head design. Sony no longer makes heads with a "cup" shape around the head, this, I have been told by Sony would help lift the tape off the heads. Sony says they don't see a problem with their newer head designs, but I do . During fast forward and rewind, the tape tension is not perfectly controlled, you can see the tape tension change with your eyes. This erratic tension prevents the tape from floating above the cylinder, even with small space designs. Backtension control is worst on the 59es/790/R300 transport designs for all combined modes of operation. For fast forward and rewind modes only, the D7/8 is on the bottom of my list. The R500, DA30MKII and SV-3800 do a good job of controlling tension in any mode. For playback and record the SV-3800 is unmatched. The Sony R500 is better on rewind and fast forward. The Tascam DA30MKII is very close in tape handling ability to these units. The R300 has a DTC790/A7 transport mechanism and is not in the same league as the R500. Tape tension is critical, not only for proper tracking, but also to minimize tape and head wear. Setting the tension too low will result in erratic operation, including dropouts and tape being eaten. Tape tension that is too high can cause excessive head wear, early tape failure and overloading the tape drive mechanism. Too much tension along with a worn upper drum produces dropouts, due to the tape "grabbing" or sticking to the head. Low grade or defective tape also causes this effect. The most common head failures I have seen are due to using low grade tape or any 90 meter DDS tape. They often clog the head so completely that they cannot be cleaned. Problems with the rotary transformers, sensors and bearings are second. Heads wearing down to the point they can no longer read data or clog very easily is third. Upper drum wear, causing excessive friction is number four. Heads that need constant cleaning to stay functional are probably worn out, although I have seen so much debris (oxide buildup) on them that they must be manually cleaned to restore proper operation. Under these conditions the oxide can become glazed onto the head, requiring a strong solvent to remove it. Keep in mind that the heads do protrude slightly from the upper drum and can be easily damaged when cleaned manually (the best cleaning method). Heads that wear to the point that the gap (the tiny split between the two sides of a head around which wire is wound to pick up induced current) changes enough to alter its frequency response will still protrude slightly from the upper drum, but the RF output is low due to gap changes. These are the heads that clog easily or playback with higher than normal error rates. A good clue to this failure is that tapes made on a machine with low output heads will playback with higher error rates on itself than other machines. Worn mechanical parts in the lower cylinder assembly can cause an audible noise as well as speed instability, which shows up as a drifting PG phase and elevated error rates. Upper drum wear shows up as speed instability, PG phase drifting, elevated error rates and irregular or incomplete rewind or fast forwarding of the tape. This type of wear is easily seen as the head is no longer shinny and the surface has taken on a dull grey look. Observed under magnification, one can see the streaks or scratch marks left on the drum assembly. This is the failure we see most often in the D7/8 portables. It first manifest itself as inability to track tapes near the end . This is due to the increase in the coefficient of friction the resulting load on the head and capstan motors. Reading the owners manual and following directions for use and care of your DAT machine will provide the user with maximum transport/head life and minimum maintenance cost.