Demagnetizing your Tape Heads
The demagnetizer must be turned on at least 3 feet from any tape or tape machine. The active end of the demagnetizer should be covered with plastic so as not to scratch. If it has a bare metal end, cover it with a layer of tape (electrical tape).
The magnetic field of the demagnetizer drops off rapidly with distance. In order to demagnetize a part you must apply a field that is strong enough to totally magnetize the part. Since the demagnetizer is running on 60 Hz AC, the polarity of the magnetic field is reversing 120 times a second.
If the power were to go off while the demagnetizer was close to something, there would be a very good chance the part would wind up strongly magnetized. In order to DEmagnetize something, the field must be very slowly be reduced in strength to close to zero. We do this by slowly moving the demagnetizer away from what we are trying to demagnetize.
Fast or jerky motions can result in magnetizing not DEmagnetizing. Move like you are in slow motion.
So the steps are:
1.Turn the power off on the tape recorder or duplicator. Demagnetizing with the power on can damage the circuitry.
2.Turn the demagnetizer on well away from tape or tape machines (3' or greater).
3.Move the demagnetizer in so the tip does not make contact the parts of the tape recorder or duplicator you are trying to demagnetize. You want to do the head(s), guides, and (if you have a strong enough demagnetizer) the capstan.
4.Move across the surface of each part and from one part to the next very slowly and smoothly. If you slip and move fast, go back over that part.
5.After you have gone over the surface of every metal part in the tape path, very slowly and smoothly move the demagnetizer away until you are at least 3' away.
6.Turn the demagnetizer off.
Some additional notes:
If you use a low power demagnetizer, you probably do not have to power to be able to demagnetize a capstan. It is not important to move slowly when moving TOWARDS the tape heads, only when near them and when moving AWAY from them.
You need to get the strongest possible magnetic field applied to the metal tape path parts you are trying to demagnetize. This requires that you get the end of the demagnetizer into contact with the parts, since the magnetic field drops off rapidly with distance. This is why we want plastic or tape over
the metal end of the demagnetizer, so we do not scratch anything with it.
You do not need to hold the demagnetizer in position for any amount of time. All you need to do is:
1.Get a strong enough alternating magnetic field
2.Reduce that field strength slowly.
Pulling away slowly and smoothly is very important. You want to demagnetize not only the tape head(s), but all metal parts that touch the tape.
The only way you can damage things while demagnetizing would be to do it with the equipment power turned on, to kill the power while the demagnetizer is close to the equipment, or to move fast or jerky.
I would be very cautious cleaning the rubber pinch roller with anything BUT soapy water. Solvents and alcohol can damage the rubber by dissolving it and making it sticky and crack.
