Marantz 4415 - AMPLIFIER AND POWER SECTIONS; MAIN AMPLIFIER; POWER SUPPLY UNIT; AUDIO TROUBLE ANALYSIS

providing vanished sound image positioning.
In the SQ DECODER position, signal sources encoded by the CBS SQ system are ideally
decoded into 4-channel signals. Required for this operation is incorporation of the SQ Adaptor,
Model SQA-1, into the Model 4415.
4.2 Balance Control
Signals from the tone control amplifiers are fed into the balance control circuit, in which the
signals are controlled by three balancers: FRONT L-R, REAR L-R, and FRONT-REAR. By
setting the FRONT-REAR balancer to the ‘‘FRONT"” side and the FRONT L-R balancer to the
’L"” side, for example, only the front left channel is drived.
The balance control circuit is provided with the remote control switch which makes the
Mode! RC-4 Remote Control Box operative when set to the ““REMOTE” position. In the
“REMOTE?” position the balancers on the Model 4415 become ineffective since signals are led to
the Model RC-4. The volume level can be adjusted by the volume control either on the Model
4415 or Model RC-4. However, the maximum volume level available by adjustment of the Model
RC-4 is determined by the volume contro! on the Model 4415. |
| Balance controlled signals are led through the hi filter to the main amplifier section for
further power amplification.
5. MAIN AMPLIFIER
Transistor H601 is the pre-driver coupled to the transistor H603 through capacitor C609. The
transistor H603 drives the inverter transistors H609 and H611 which, in turn, drive the power
stage consisting of HOO1 and HOO2. Transistors H605 and H607 are current limiter operating as a
power transistor protection circuit.
Excessive current flow in the power output stage is detected by the resistors R645 and R651
and the resultant variation is applied to the transistors H605 and H607 and make them turned
on. This decreases the base biasing current for H609 and H611. In this way the current flow in
the power output stage (HO01 and HOO2) is restricted within a safe predetermined value.
6. POWER SUPPLY UNIT
The power supply unit consisting of transistors H801 and H802, which operates as an
automatic voltage regulator provides +35V DC to all of the amplifiers except main amplifiers and
+14V DC to the tuner section.
AUDIO TROUBLE ANALYSIS
Excessive line consumption a. Check for shorted rectifiers HO13.
b. Check for shorted transistors HOO1 through HOO8.
Check LOOQ1 for short.
2. No line consumption or zero bias. a. Check line cord, fuse, shorted HOO9 through HO12,
H713 & H714.
Check for open rectifiers HO13, or open L001.
Check filter capacitors CO05, C605, & C606.
Check for shorted transistor H802.
Check for defective capacitors, C607, C608, C611,
C612, C625 & C626. 7 |
5. Improper clipping a. Check for proper adjustment of R617 & R618.
—_= sl
3. Excessive hum and noise level
2 Oo So:
4. Parastic oscillation