Akai GX 630 D Service Manual

Page 2

AKAI STEREO TAPE DECK
MODEL GX-630D

ALSO APPLICABLE TO MODEL GX-630DB STEREO TAPE DECK

SECTION I SERVICE MANUAL .......................... I
SECTION 2 PARTS LIST ................................ 25

Page 17

oowywoo

O 0 rest Polur.a @TEST POINT o O

VRZB 5K3 anb IKE VRI IKE Vfid 5K3

"@ WE e- (@ "
4I|@ )Jll® 4© @III- @IIF

l 4] L

RIGHT CHANNEL

U

LEFT CHANNEL

DOLBY NR PC BOARD TD-530l

5.DOLBY NOISE REDUCTION ADJUST-
MENT (Model GX-630DB) (Refer to Fig.
15)

PART-1. RECORDING DOLBY N.R CIRCUIT
ADJUSTMENT

Disconnect the wire connected to Dolby circuit input

and output terminals (A) and (B). Connect an Audio

frequency oscillator to terminal (A) and connect a

High-sensitivity VTVM to terminal (B).

1) Turn semi-fixed resistors VRl lkB and VR2 5 kB
fully clockwise (Fig. 15)

2) Ground test points T.P (Fig. 15)

3) Set Dolby Switch to OFF position.

4) Supply a 5 kHz, -10 dBm signal which has been
verified with a frequency counter from the audio
frequency oscillator and confirm that at this time
the indication of the high-sensitivity VTVM con-
nected to terminal (B) is 0 dBm.

5) Reduce the output of the audio frequency oscil-
lator by ~30.5 dB from the condition outlined in
item 1-4) (5 kHz, 740.5 dB) and at this time
confirm that the indication of the high-sensitivity
VTVM connected to terminal (B) is -30.5 dB.

6) Set Dolby Switch to ON position and adjust
semi-fixed resistor VRl 1 kB to obtain a ~20.5
dBm indication on the high-sensitivity VTVM
connected terminal (B).

7) Disconnect ground wire from test point T.P
(grounded in item 1-2) and at this time adjust
semi-fixed resistor VR2 5 kB to obtain a -22.5
dBm indication on the high-sensitivity VTVM
connected to terminal (B).

Fig. 15

NOTE: Identical P.C Boards are utilized for Record-

ing Dolby N.R and Playback Dolby N.R
The Recording Dolby N.R P.C Board is
located on the Recording Amp P.C Board
and the Playback Dolby N.R P.C Board is
located on the Playback Amp P.C Board,
Adjust left and right channels respectively.

PART-2. PLAYBACK DOLBY N.R CIRCUIT

ADJUSTMENT

This adjustment is carried out in essentially the same
way as the recording Dolby circuit adjustment.
Disconnect the wire connected to input and output
temtinals(A) and (B), connect and audio frequency
oscillator to terminal(A), and connect a highsensi-
tivity VTVM to terminal(B). Tum semi- fixed resistor
VRl 1 RB and VR2 5 kB fully clockwise, and ground
test points TP.
1) Set Dolby Switch to OFF position and supply 215
kHz, 10 dBm signal which has been verified with
a frequency counter from the audio frequency
oscillator, Confirm that the high-sensitivity VT'VM
indication at this time is 0 dBm. Next, lover the
oscillator output by -22.5 dB and confirm that
the high-sensitivity VTVM indication is -21.5 dB.
2) Set Dolby Switch to ON position and at ths time
adjust semi-fixed resistor VRl 1 kB to obtain a
-32.5 dB high-sensitivity VTVM indication.
Next, disconnect ground wire from test points T.P
and adjust semi-fixed resistor VR-2 5 kB toobiain
a 730.5 dBm indication.

Dolby is a trademark of Dolby Laboratories, Inc. Under License from Dolby Laboratories. lnc. 15

Page 35

5) BRAKE PLUNGER BLOCK
Refr

N0. Parts No. Description SChfitfi Q'tY
5-lx 32637986 Brake Plunger Block Comp. TE 1
5-2 M2643498 Plunger Retaining Plate TE-zols 1
5-3 131638695 Plunger Solenoid 124011-113 +30 1
5-4x 150570273 Silicon Diode LN4004 45-2-59 1
5-5): 25422076 Screwr pan head 3x5 2
5-6 ML643476 Brake Plunger Lever TE-zau 1
5-7 MH2S7477 Connecting Pin 110-211 1
5-8 ZW270088 E Ring 1.9M 6-1-9 1
5-9 ML643387 Brake Band Lever TE-zols 1
5-10 25323728 Screw, binding: head 3x5 6
5-11 26586427 Reverse Spring CP-nez 1
5-17. ML533643 Brake Lever B Tw-wao 1
5-13 MT314987 Brake Band Mil-213 2
5-14 M2314998 Brake Band Retaining Plate WM 4
5-15 25417137 Screw, binding head 3x4 8
5-16 ML582074 Brake Band Support TD-lm 2
5-17 ZW290283 U Ring 2.85M 6-1-1 2
5-13 ML582041 Brake Lever A TD~1019 l
5-l9x M2317406 Brake Band Guide MR'IZD 2
5-20x 28413166 Screw, round head 3x6 4
5-21 MZ314605 Spring Rack, MR MR-m 2
5-22 23379405 ISO Screw, binding head 3x6 4
5-23 26540090 Brake Lever Spring Tw-losfl 2
5-24 25422076 Screw. pan head 3x5 2
5-25 E5573456 Micro SW. K-2 25-1-30 2
5-26 zw39714a Micro SW1 Nut KD-ifls1 1
5-27 28608354 Scres, pan head 3x30 2
5-28 ER450786 Spark Quencher U/L

0.1ptl200hm 400WV 01-1-33 1
6) TENSION ARM BLOCK

23' Parts Nor Description 5mm Qty
6-1 ML580443 Tension Arm Base, w/metal TD-mr 1
6-2 145645502 Tension Shaft TD-Zml 1
63 2w580498 Tension Arm Washer TD-znoz 1
6-4 ZW575763 Washer (SPC) D511x13x0.51 2
6-5 ZW260256 Washer (PBP) DB.lx13x0.lt 2
6-6 MH144710 Flywheel Fixing Pin 939-25 1
6-7 MHSBOSSS Damper Prop TD-2052 1
6-8x TC387617 Clutch Felt CS-Zflll 1
6-9 MZ580577 Clutch Plate, w/metal A TD-ZOSl 1
6-10 ML580555 Clutch Lever, wlspring

retainer TD-zots 1
6-11 ZW270156 15 Ring 6M 6-1-9 1
6-12 26580511 Clutch Spring TD-ZOM 1
6- l 3 ZW580678 Spring Retaining Washer TD-zw 2
6-14 ZW273756 Nut M3 2
6-15 ZW575774 Washer D4.Sx9r8x0.7t 1
6-16 26580533 Cramp Spring TD-zlue 1
6-17 2W410051 E' Ring 25 6-1-9 1
6-1 5 26580522 Clutch Lever Spring Til-2045 1
6-19 MZSBOSOO Cam. SW. TD~2043 1
6-20 26659608 Tension Spring TE-ZDM 1
6-21 ZWSSOG42 Washer (SPC) D3.lx7.9x0.5t 1
6-22 ZS32372S Screw, binding head 3x5 1
6-2 3x M2810 191 Cushion Rubber, RD 110-275 1
6-24 ML580465 Tension Arm, w/guide B PD-2039 1
6-25 zw535094 Decorative Washer TW-207I 1
6-26 25200384 Screw. countersunk head 3x6 1
6-27 M2580680 Actuator TD-zoss 1
6-28 ZW290283 U Ring 2.85M 6-11 1
5-29 ESS734SG Micro SW. K-Z 254-30 2
6-30 28508354 Screw, pan head 3x30 2
6-31 28413155 Screw, binding head 3x6 4