Yamaha mx u

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YAMA-002 01

STEREO POWER AMPLIFIER

MX-BOO/U/MX-70

SERVICE MANUAL

W
IMPORTANT NOTICE

This manual has been provided for the use of authorized Yamaha Retailers and their service personnel.

It has been assumed that basic service procedures inherani to the industry, and more specifically Yamaha

Products, are already known and understood by the users, and havt 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 all service required should be performed by an authorized Yamaha Retailer or the
appointed service representative '

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

The data provided is believed to be atwraxe and applicable to the unitls) 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 subiect to change without notice or

obligation to 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 me ground buss in the unit (heavy
gauge black wires connect to this buss).

IMPORTANT: Turn the unit OFF during disassembly and parts replacement. Recheck all work before
you apply power to the unit.

TO SERVICE PERSONNEL . . . . . . . . . . . . . . . . . DISASSEMBLY PROCEDURES . . . . . . . . . ..... 5

SPECIFICATIONS
FRONTPANELS
REARPANELS..... .. .
BLOCKDIAGRAM
INTERNALVIEW

ADJUSTMENTS 5
PRINTEDCIRCUITBOARD .............6~13
SCHEMATICDIAGRAM.. 14/15
WIRING.............. ...........16
PARTSLIST.......................17~25

buhwnaa

-

YAMAHA

YAMAHA CORPORATION
P.O.Box 1. Hamamatsu. Japan

3,8K-2l3 n (D

3
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MX-BOO/U/MX-7O

ITO SERVICE PERSONNEL

1. Critical Components Information.
Components having special characteristics are marked &
and must be replaced with parts having specifications equal
to those originally installed.

2. Leakage Current Measurement (For 120V Model Only),
When service has been completed, it is imperative that you
verify that all exposed conductive surfaces are properly
insulated from supply circuits.

0 Meter impedance should be equivalent to 1500 ohm shunted
by 0.1 SuF.

- Leakage current must not exceed 0.5mA.

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

EQUIPMENT
UNDER TEST

AC LEAKAGE TESTER
OR EQUIVALENT

f

:l
INSULATING TABLE

@20-

WALL
OUTLET

0 POLARIZATION (U, 0 models only)

This amplifier product is equipped with a polarized alternat-
ing current line plug (a plug having one blade wider than the
other ). This plug will fit into the power outlet only one way.
This in a safety feature.

I SPECIFICATIONS
Minimum RMS Output Power per Channel
20H: ~20kHz
0.003% THD, 89 170W
0.007% THD, 60 195W
0.02% THD, 4n 230W

Dynamic Power per channel
(by IHF Dynamic Headroom measuring method)
an

270W
an 330W
49 440W
20 570W
1 a 600W

DIN Standard Output Power per Channel

1 kHz, 1% THD, 4n 250W (G)

Dynamic Headroom
2.01 dB (U. C, R)

an 2.23dB (U, 0, Fl)

49 2.82dB (U, C, R)
IEC Power (1kHz, 0.01% THD)

89 200W (G)

69 240W (G)

49 280W (G)
Power Band Width

0.03% THD, 85W, an 10kHz ~60kHz

Damping Factor
8n. 1 kHz 90

Input Seneltivity/lmpedanee
MAIN IN

1.32V/60kn

Frequency Response (20H: ~20kHz)

MAIN IN +0, -0.2dB
Total Harmonie Distortion

20Hz ~ 20kHz

MAIN IN TO SP OUT (85W/Bn) 0.003%
Intermodulation Distortion

Rated Output I851 0.003%
Signal to Noise Ratio (IHF-A Network)

MAIN IN (shorted) 124dB

MAIN IN (5.1kSZ terminated) 120dB
Residual Noise (IHF~A Network) 21uV
Channel Separation (Vol. -30dB)

Input Shorted (l kHz/1 OkHz) 89dB/72dB

Power Supply
AC22OV, 50H: [(3)
A0110/120/220/240
v. 50/60Hz (R)
AC240V, 50H: (A, B)
AC120V, 60H: (U, 0)

Power Consumption
650W, BDDVA (U, C)
520W (Fl)
115OW (A, B, G)

AC Outlet

Un Switched x 1

200W max. (U, C, RI
Dimensions (W x H x D)

435 x 170 x 425mm
(17-1/8" x 6-11/16" x
16-3/4")

14.5kg [31 lbs 15 oz)

Speclficetion: are sub/act to change without notice.

.. U.S.A. Model
Canadian Made]
Austmlian Model
British Model
European Modal
.. General Model

Weight

o DIMENSION

i
in:
{$15

Fl FIFI FIFI Fl
2
B
é
Z
3
w I_l I-l A
.ne
a
DD: 0 O 0
El . . a ===. g
I_i L;r -
435 (i7-i/e") a:

Unit: mm (inch)