Operating instructions

5.1 Demagnetizing and Cleaning the Tape Path
The following items are necessary to perform the maintenance procedures
outlined in this section.
❑ A head demagnetizer (degausser).
❑ Pure isopropyl alcohol for head cleaning.
❑ Lint-free cloth and cotton swabs.
CAUTION: Do not use rubbing alcohol as it can leave water and oil residues.
Do not use other solvents as they may delaminate the heads.
5.1.1 Demagnetizing the Heads and Tape Guidance Path
Demagnetizing (sometimes called degaussing, although that term more often
refers to bulk tape erasure) is a necessary procedure and should be
performed prior to every alignment and recording session. It should always
be done with extreme care.
DEMAGNETIZING CAUTION: To avoid damaging the MTR-90III, always make
sure the POWER switch is off before proceeding. The AC field created by the
demagnetizer is extremely powerful and could seriously damage electronics
if they are powered up. Also, remove all recording tape, especially alignment
tapes, from the vicinity of the MTR-90III when performing these procedures.
DEMAGNETIZING CAUTION: Never turn on or turn off the power to the
demagnetizer unless it is at least 1 meter (3 feet) away from the MTR-90III.
The demagnetizer creates an especially strong moving magnetic field which
could possibly place a permanent magnetic charge on parts of the tape
machine. The demagnetizer would not be powerful enough to remove such
charges under normal operating conditions, and the parts might therefore
have to be discarded. Use only a professional demagnetizer of high flux
density; inexpensive "HI-FI" type demagnetizers can leave residual fields
that will cause more harm than benefit.
1. Turn off the power.
2. With the demagnetizer at least 1 meter (3 feet) away from the MTR-90III,
plug the demagnetizer into the power mains and turn it on.
3. Slowly move the demagnetizer toward the Supply swing arm roller (on
the left side of the transport) until the tip is about 3 mm (1/8") away.
4. Slowly move the demagnetizer tip up and down along the roller, while
simultaneously turning the roller with the other hand so that the entire
roller surface is directly exposed to the demagnetizing field.
WARNING! Do not touch any MTR-90III parts with the demagnetizer.
5. Slowly move the demagnetizer at least 1 meter (3 feet) away from the
MTR-90III.
Section 5 Maintenance
5 - 2
October 1990
MTR-90III Operation and Maintenance Manual