Yamaha kx 390

Page 1

STEREO CASSETTE DECK

KX-390/490

SERVICE MANUAL

( V IMPORTANT NOTICE \

I This manual has been provided for the use of authorized YAMAHA Retailers and their service personnel.
It has been assumed that basic service procedures inherent to the industry. and more specifically YAMAHA
Products. are already known and understood by the users, and have therefore not been restated,

WARNING: Failure to follow appropriate service and safety procedures when servicing this product
may result in personal injury, destruction of expensive components, and failure of the
product to perform as specified. For these reasons, we advise all YAMAHA product owners
that any service required should be performed by an authorized YAMAHA Retailer or the
appointed service representative,

IMPORTANT: The presentation or sale of this manual to any individual of firm does not constitute
authorization, certification or recognition of any applicable technical capabilities, or
establish a principle-agent relationship of any form.

The data provided is believed to be accurate and applicable to the unit(s) indicated on the cover. The research,
engineering, and service departments of YAMAHA are continually striving to improve YAMAHA products
Modifications are. therefore, inevitable and specifications are subject to change without notice Or obligation to

06l7/069'XM

retrofit. Should any discrepancy appear to exist. please contact the distributor's Service Division,

WARNING: Static discharges can destroy expensive components. Discharge any static electricity your
body may have accumulated by grounding yourself to the ground buss in the unit (heavy
gauge black wires connect to this buss)

IMPORTANT: Turn the unit OFF during disassembly and pan replacement. Recheck all work before you

\ apply power to the unit.
I CONTENTS
TO SERVICE PERSONNEL . 1 SCHEMATIC DIAGRAM (KX-390)...
WARNING .......................... 1 SCHEMATIC DIAGRAM (KX-490)
FRONT PANELS .. 1 PRINTED CIRCUIT BOARD (KX-490) ................... 18~21
REAR PANELS 1 SCHEMATIC DIAGRAM (Mechanism) (KX-490) ..... 22
DISASSEMBLY PROCEDURES (KX-390) 4 DISASSEMBLV PROCEDURES (KX-490) . . 23,24
SPECIFICATIONS (KX-390) . 5 SPECIFICATIONS (KX-490)
DIMENSIONS (xx-390) ..... 5 DIMENSIONS (xx-490)
INTERNAL VIEW (KX-390) INTERNAL VIEW (KX-490)..
ADJUSTMENTS (KX-390) ADJUSTMENTS (KX-490)
u-COM DATA (xx-390) ........ u-COM DATA (xx-490) .......
BLOCK DIAGRAM (KX-390) BLOCK DIAGRAM (xx-490)
PRINTED CIRCUIT BOARD (KX-390) PARTS LIST .........................

SCHEMATIC DIAGRAM (Mechanism) (KX-390)

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AHA

YAMAHA CORPORATION
P.0.Box1 .Hamamatsudaoan

2,9K-791 ® g Printed in Japan 96.?)

Page 2

KX-390/490

m
KX-490

I TO SERVICE PERSONNEL

1. Critical Components Information,
Components having special characteristics are
marked A and must be replaced with pans having
specifications eqdal to those originally installed.

2. Leakage Current Measurement (For 120 V Model

Only).
When service has been completed. it is imperative
that you verify that all exposed conductive surfaces
are properly insulated from supply circuits.

- Meter impedance should be equivalent to 1500 ohms
shunted by 0.15 pF.

- Leakage current must not exceed 0.5 mA.

. Be sure to test for leakage with the AC plug in both
polarities.

EQUIPMENT AC LEAKAGE TESTER
UNDER TEST OR EQUIVALENT
I
0mg 1:: L-
ET INSULATING TABLE
III] DOLBY B-C / DOLBY B-C-S

Dolby noise reduction and HX PRO headroom exten-
sion manufactured under license from Dolby Laborato-
ries Licensing Corporation. HX PFIO originated by Bang
and Olufsen. Dolby", the double-D symbol and HX
PFIO are trademarks of Dolby Laboratories Licensing
Corporation.

I WARNING: CHEMICAL CONTENT
NOTICE!

The solder used in the production of this product
contains LEAD. In addition, otherelectrical/electronic
and/or plastic (where applicable) components may
also contain traces of chemicals found by the
California Health and Welfare Agency (and possibly
other entities) to cause cancer and/or birth defects
or other reproductive harm. ~ .

DO NOT PLACE SOLDER. ELECTRICAL/
ELECTRONIC 0R PLASTIC COMPONENTS IN
YOUR MOUTH FOR ANY REASON WHAT SO
EVER!

Avoid prolonged, unprotected contact between
solder and your skin! When soldering, do not inhale
solder fumes or expose eyes to solder/flux vapor!

It you come in contact with solder or components
located inside the enclosure of this product, wash
your hands before handling food.

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....... .-.-----..u....u
.m..--..---~.-_mm

I FRONT PANELS
O KX-390
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Page 15

KX-390/490

27

Item to be I l
Step Adjusted Tape . mflmt Mode Adjtgtrmem Rating Remarks

4 Tape speed MTT-111N Wow/nutter meter PLAI Potenflometer 3005 Hz i 15Hz - Pertorm adjustment

3 kHz. -10 dB at Frequency at the back of at the position where
counter the capstan the test tape is
motort (Fig. C) advanced/rewound tn
the middle,

5 Wow/flutter M1T-1 1 1 N Wow/flutter meter PLAY Less than 0.14%

3 kHz. -1 0 dB ' (EIAJ, WRMS)

Line out L: on 1
Line out Fl: ch 2

Capstan motor

DC input: X-Y (Resurge) mode
OK NG
Screw driver
Azimuth adjustment screw Fig. A Fig. B Fig. C
* Standard level of this machine is that 250 nWb/m is 0 dB. (-5 dBV at LINE OUT)
0 PLAYBACK ADJUSTMENT
step at? we 'liéfll'éa um lane" Melitta. imam swomcauon
1 Playback MTT-212N ACVM PLAY VRS (Leh) LINE OUT When MTf-212N is 465V i 0.3 dBV
Level (0 dB) VR4 (Rah) played back. adiust
(315 Hz) VFl so that output level
becomes the specified
Value.
2 Playback E0 MTT-114N ACVM PLAY VR1 (Lch) LINE OUT When MIT-114M is 15UBV 1: 1 dBV
Level (10 kHl, VR2 (Rah) played back, adjust
(10 kHz) -10 (18) Wt so that output level
becomes the specified
Value.
3 Confirmation MTT-255 ACVM PLAY LINE OUT Make sure that level at 0 as $4 dB
at Playback (Normal: 3180) Oscilloscope LINE OUT jack is within
Frequency us + 120 us) the specificatlun of Fig.
Response NWT-856 D when lest tape is
(High: 3180 us played back.
+ 70 us)
0 PLAYBACK FREQUENCY RESPONSE
I __
a .I a l | e
3 -l-~ 3 -l- '"
+l | 44 "1
. | 'H
I l l'
, l l I I 1
I | | | | l |
50 250 315 IK 3K 10K izesx
Fig. D