Eventually, everyone will experience video tape
recording problems. Heads wear out. When and what to look for are the subject of this
When it comes to video heads, think of them like
your auto’s tires. I recently replaced the tires on my SUV at 45000 miles, even though they were
not worn out according to safety inspection standards. I did not feel completely safe driving on
snowy roads with marginal tire treads. My preferred tank-like traction came back after replacing
the tires. I valued safety over cost.
By understanding the headwear cycle you can
prepare yourself for inevitable problems. Spinning video upper drums have a number of imbedded head
tips that lay down the picture, sound and time-code information (depending on format). Head tips
project out of the drum surface, and into the surface of moving tape stock. By design, these heads
have a self-cleaning ability that is maximum when new. As the tip projection decreases, the
self-cleaning ability is also reduced.
The second problem with worn heads is that the
less head tip projection into the tape (head to tape contact), the poorer the quality of the
recorded signal on the tape. The same applies to playback of a recorded signal. Dropout
compensators, or error correction, can handle only so many signal drops before the picture or sound
How do you determine when it’s time to replace
your video heads? If you are diligent and check playbacks of your recordings you will sense the
change in quality over time. With the larger Betacam heads, head tip projections can be measured.
There is a comparison range of new head projections to worn out heads that will be a good guide on
when to replace the head drum. Smaller Betacamcorder drums have new head projections of 18 to 21
microns, and are worn-out at about 9 microns. Larger Betacam head projections are 30+ microns when
new, and worn at about 15 microns.
Smaller DV, DVCAM, and DVCPRO drums are not easily
measured because of cramped transports and lack of proper measuring devices. The starting place or
guide to replacement time can be found in the maintenance manuals for each video product. For
example: BVW-D600 (Betacamcorder) 500 hours, DSR-500 & DSR-PD150 (DVCAM) 1,500 hours, AJ-SDX900
(DVCPRO) 2,000, and AJ-HDC27 (DVCPROHD) 2,000 hours. These numbers are recommended, however heads
can sometimes fail sooner or later. Tape stock can vary in abrasiveness and tape transport tensions
can increase over time, which will increase headwear.
Almost all video recorders have drum hour meters
which should be checked periodically. It is always a good idea to monitor drum hours on your decks
while looking for signs of problems. Check your operation manual for information on accessing your
Analog video recorders show a more gradual
deterioration of quality than do digital recorders. With digital error correction there is much
less warning of up coming head wear problems. It is your individual choice to preventively replace
your heads or wait until they fail. You have a choice of maintaining your gear or repairing
As I mentioned in my car story, safety and
reliability were my main concern. I preferred safety above cost.