Rotel RA 312 Service Manual

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HOTEL:

PIA-312

STEREO PRE/MAIN AMPLIFIER

For Serflce Manual-
MAURHRON SERVICES
8 Cherry The Road, Chlnlmr -

°§$26¥§2§33§¥6§?

TABLE OF CONTENTS _ emaiaiafiléfiifiifimk _
CHASSIS LAYOUT -------------------- 1 -
PRECAUTIONS ....................... 1

MAIN AMP. BIAS ADJUSTMENT --------- 2

GAIN DIAGRAM ................... . 2

TROUBLE SHOOTING ---------------- 3

REPAIR PARTS LIST ------------------ 4

SCHEMATIC DIAGRAM ---------------- 5

MONITOR CIRCUIT BOARD DIAGRAM - -- e

FILTER CIRCUIT BOARD DIAGRAM ..4. 5

PRE/MAIN AMP & POWER SUPPLY

CIRCUIT BOARD DIAGRAM ------------ 7

:TECHNICAL MANUAL:

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CHASSIS LAYOUT

53T95n?5"!"7

$9,'Power Switch

S2, Speaker Selector
Headphone Jack

Bass Control

Treble Control

56, Loudness Switch
S7, High Filter Switch
Balance Control ..
58, Low Filter r .
Volume Control 1- '
85, Mode Switch. ' 'K
S4, Tape Moniter-l Switch.
83. Tape Moniter-Z Switch.
51. Function Selector
lC401, Phono Amp. IC.
Phono Din Jack i- g ,-
0613, Power Amp. (L-ch) I
Input Terminal

0611, Power Amp. (L-ch)
Tape Monitor Din Jack
Tape Monitor Terminal
0612, Power Amp. (Fl-ch)
0614. Power Amp. (R-ch)
Speaker Fuse

F901, AC Fuse

Speaker Terminal 1 and 2
AC Outlet 1 and 2

T001, Power Transformer

PRECAUTIONS

Always disconnect the chassis from power line when
soldering. Turning the power switch OFF is not enough,
Power line leakage passing through the heating element
may destroy the Transistors.

Never attempt to do any work on the transistor
amplifiers without first disconnecting the AC line cord
and waiting until the power supply filter capacitors have
discharged.

Replacement for output and driver transistors, if
necessary, must be made from the same hfe group as

the original type.

If one output transistor burns out (open or short)

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always remove all the output transistors in that channel
and check the bias adjustment, the control and other
parts in the network with an ohm-meter before inserting
a new transistor. All transnstors in one channel will
be destroyed it the base biasing circuit is open on the
emitter end,

When mouting a replacement power transistor, be sure
that the bottom of the flange, the mica insulators and
the surface of the heat sink are free of foreign matter,
for they may cause transistors failure.

Silicon grease must be applied between the transistor
and the mica insulator, and between the mica insulator
and the heat conduction