Getting the Grunge Off
Your Tape Heads
It's tempting to think that forking over a chunk of money
for an audio or videocassette recorder will guarantee reliable, like-new performance
forever . . . or at least for a very long time. Indeed, good electronic equipment is hardy
stuff, and should chug along with few problems for years, but that doesn't mean problems
won't arise from time to time. Often enough, things that cause deterioration of the signal
can be cleared up fairly easily, but it's better to get into the habit of looking after
your stuff before it starts doing funny things. Most potential problems can be averted by
some simple routine maintenance.
With an audio cassette deck, one procedure that should be
carried out frequently is a routine cleaning, to get rid of oxide that builds up over time
on anything that comes into contact with the tape. This is particularly important if you
play a lot of prerecorded cassettes, which are often duplicated on inferior tape stock.
You should take care that the heads, tape guides, capstan,
and pinch-roller are free of oxide, as a buildup on any of them can cause the tape to skew
as it goes by the heads. Contamination on the heads themselves can seriously degrade
treble performance as well.
Unfortunately, the heads and tape guides are hard to reach
in many decks, in which case a special head-cleaning cassette is probably the best bet.
Otherwise, a cotton swab and a drop of pure isopropyl alcohol or head-cleaning fluid will
work well. Keep at it until you can no longer see a telltale brown smudge on the swab.
Figure on a cleaning after every ten or twelve hours of use. Oxide buildup can be
difficult to spot, so don't wait until you can see discoloration on the heads or capstan;
it's better to assume it's there than to wait until it becomes audible.
You should also demagnetize your deck once in a while. Over
time, metal parts that come into contact with the tape can pick up a residual magnetic
field, which can add noise during recording or, more seriously, progressively erase the
signal on already recorded tapes, resulting in a permanent loss of treble that will become
worse with each playing.
Demagnetization is a tricky maneuver that can make matters
worse instead of better if it's not done right. The procedure is best performed by a
special cassette designed for the purpose (available from several tape manufacturers).
This is a battery-operated device that pops into the machine like a normal cassette and
runs for a few seconds in the play mode. Fortunately, modern cassette decks are much less
susceptible to magnetization than older machines, so you needn't -- and probably shouldn't
-- demagnetize nearly as often as you clean.
As for the tapes themselves, careful storage is usually all
that's necessary. But one thing that can do serious damage to a tape is a stray magnetic
field, whether from your equipment (TV sets, loudspeakers, and amplifiers have quite
strong fields) or from nearby non-audio sources, such as magnetic latches on cupboard
doors. All of these can erase tapes, in part or completely, and should be avoided.
Fortunately, a gap of about a foot between your tapes and any of these common sources of
magnetism is almost always enough to prevent harm.
Videotapes are also susceptible to problems from extraneous
magnetic fields, and so the same precautions apply.
When it comes to the video recorder, the delicacy of the
mechanism dictates that you interfere with it as rarely as possible. Chances are you'll
never have to demagnetize, as video is less apt to pick up residual magnetism than audio
equipment, but there are times when you may have to clean the heads and guides. A very
snowy picture from a previously clear tape is the usual clue.
Often simply playing the tape once or twice will fix the
problem by dislodging bits of oxide that have stuck themselves to the heads. If things
don't improve on their own in short order, however, you may have to take more drastic
measures. Usually that means using a special head-cleaning videocassette.
These come in two sorts: wet and dry. The wet versions
usually require you to squirt a cleaning solution into an opening in the cassette, and
then to "play" the tape for a few seconds while the liquid-impregnated fabric
tape washes the heads. This may or may not be effective, depending on how much grunge is
on the heads and how long it's been there.
Dry cleaners are abrasive, and grind the dirt off the head
surface. If you're not careful, however, they'll grind the heads themselves and cause
permanent damage, so they should only be used for a few seconds at a time. Keep checking
to see when your snowy tape is clear.
Video head cleaning should normally be done only when
necessary. Heavy tape users sometimes use the only really safe method: opening up the
recorder and carefully cleaning the individual surfaces with cotton swabs and heads
cleaners. This is definitely not recommended for those not trained to do it, so if
your use is unusually heavy, consider having the heads cleaned professionally about once a
year.
...Ian G. Masters
ian@mastersonaudio.com
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