JVC DD-9 A - Main Adjustments; Equipment and Measuring Instruments; Mechanical Adjustment; Head Adjustment

Main Adjustments
DD-9A/B/C/E/S/U
[I] Equipment and measuring instruments used for adjustment
1. Electrical adjustment
1) Electronic voltmeter
2) Audio frequency oscillator
(range: 50—20 kHz and output 0dB with impedance
600 (2)
3) Attenuator
4) Standard tapes for REC/PB
Maxell UD — SF tape ..........
TDK SA — SAtape........... } or equivalent
JVC ME — Metal tape.....-.-.-.-.
5) Reference tapes for playback (JVC Test Tape)
VTT-658 (for head azimuth adj.)
VTT-656A-S (for motor speed, wow flutter adj.)
VTT-664 (for Reference Level 1 kHz)
VTT-675N (for playback frequency response)
6) Resistor
600 {2 (for attenuator matching)
2. Mechanical adjustment
1) Torque testing cassette gauge
2) Blank tape (C-120) for tape running checker.
[01] Mechanical adjustment
Electronic
Voltmeter.
Go
Z.
Audio Freq. Osc.
@e@e weias Scooo
DD-9
Fig. 9
(Adjust the mechanism or confirm that it is in normal operating condition prior to the adjustment of the electrical circuit.)
Head adjustment
Back-tension pad
Spring position
1. After installing the specified parts in the appropriate
positions:
A. Snug screw (1)gently, then back off about two turns.
This makes the heads nearly horizontal.
B. Snug screw (2) gently, then back off about one turn.
This will roughly position the tape in the center of the
tape path.
For tightening screw 2), use a home make screwdriver,
filed down to the specifications shown below. The same
screwdriver can be used to tighten screw Q)
Pad (attached to the cassette)
Combination head
Tape
Capstan
Pinch roller
Screwdriver
1~2 mm
oe ie
2—2,5 mm
Fig. 10
2. Make sure that the moving part of the erase head
assembly moves smoothly around the pivot of screw
and also confirm that there is enough clearance (A) in
the play mode.
3. Next, make an operational adjustment. Load a C-120
cassette and adjust the height of the erase head by turn-
ing screw Q). Watching that the tape does not curl at the
guides of both the combination and erase heads is indi-
cation of proper adjustment.
Tape Tape Tape
guide guide guide
E= Ee E
———
Correct Incorrect Fig. 11
No. 4198