Hitachi DR100E Service Manual page 13

ADJUSTMENTS
Adjusting and Checking the Electrical Section
Measuring instruments needed for the adjustments
1. Low frequency oscillator
2. Variable resistance attenuator
3. Electronic voltmeter
4. Oscilloscope
5. Frequency counter
6. Adjustment screwdriver
7. Test tapes MTT-111, MTT-114N, MTT-150, Type1 tape (UD-1)
8. Mirror cassette for the transport (A-BEX TCC-902)
Adjustment precaution
1. Before adjustments, use gauze or a swab moistene with alcohol to wipe the surface
of the heads, the capstan shaft, and the pinch roller.
2. Demagnetize the record/playback head and the erase head with a head eraser.
3. Completely demagnetize the driver to be used for the adjustments.
4. Unless otherwise specified, set the various operation controls as indicated below.
Dolby NR switch: Off
1. Tape transport check
Load the mirror cassette for the transport, and illuminate the area around the fixed guide
of the record/playback head with a lamp and observe.
Check that the tape edge is not hitting the tape guide portion.
Note that the tape transport is the greatest factor affecting the performance of the cassette
deck.
Never move the inspection locations without good reason.
2. Tape speed check and adjustment
1. Connect the frequency counter to the LINE OUT pin and load the test tape (MTT-
111).
2. Playback FWD side of the test tape. At about halfway through the tape, where the
tape transport is stable, confirm that the frequency counter will have a reading
within the range of 3,000 Hz ±10 Hz.
3. Check REV side also that the counter reading indicates within 2955~3045Hz. Note:
Adjust within 30 seconds, after pre-heating (Play) of 20 min, or more.