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(3) STANDARD MAINTENANCE
Whenever a unit is brought in for service or repair, it should be cleaned and lubricated and the
head should be demagnetized.
1. Cleaning: Clean the heads and all tape handling surfaces using a standard cleaner and cotton
swabs. Wipe
dry.
2.
Demagnetization:
Do not use magnetized tools near the head, since they can magnetize the
head. With normal use, the head will retain small amounts of residual magnetism (this result
in increased noise and loss of high-frequency response). Use a standard tape head demagnet-
izer to demagnetize the head.
3. Lubrication: Use a high-grade of specially formulated grease in the marked places. Lubrica-
tion is normally required only when parts tend to bind, or after long periods of use. Use all
lubricants very sparingly and avoid contact with other parts.
Grease may be applied to the sliding surfaces indicated with
@
as shown in Figure 2.
(Do not use oil.)
Figure 2
(4) CIRCUIT ADJUSTMENT
Adjustment of the Tape Speed
Load the unit with a 3 kHz test cassette such as MTT-111. Use a Frequency Counter connected
to the audio output across 8 ohm
speaker.
Adjust the 350
n,
Variable Resistor so the Frequency
Counter reading is 3,000 Hz +0.33/+o.67%.
Adjustment of the Recording Bias
Adjust R6 so that the Audio Volt Meter indicates 66 mV RMS (voltage across R15) with a 50 -
52 kHz test frequency at
T2.
(Figure 3)
Pre-adjustment Procedures
1. Be sure to demagnetize and clean head before proceeding with the Head Adjustment.
2. For the Head Adjustment, never use a magnetized screwdriver.
-
Figure 3
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5
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