9-2
CIRCUIT DESCRIPTION FOR POWER4-MODULE
Supply-part
General (pos. numbers refer to circuit diagram chapter 9-7)
The primary circuitry depends on the version:
Y Versions with fixed primary voltage:AC for /26100V
120VAC for /37
220-240VAC for /22/25/30/33/34
Versions /22/25/26/37 use radial type-fuse 1201, versions /30/33/34 use glass tube fuse 1202.
For correct replacement see service printing on printed board respectively version table in circuit diagram or partslist.
Y Version with switchable primary voltage: 110-127/220-240VAC for /21
In version /21 voltage selector 1210 is built-in and each primary winding is protected separately (fuses 1201 and 1200).
For correct replacement see service printing on printed board respectively version table in circuit diagram or partslist.
Y European versions � Olow power standby feature�
For detailed description see below.
Circuit details:
Y Low power standby feature
An additional small standby transformer, connected in series to the mains transformer, reduces power consumption in
standby-mode.
In case power is switched on, the control line ECO is low ? relay 1208 is activated ? standby transformer 5211 is
shortened and out of work.
When the set is switched off (standby) the control line ECO is high ? relay 1208 is not activated ? standby transformer
5211 is now connected in series to the primary winding of the mains transformer 1008. As the impedance of the standby
transformer is much higher than the impedance of the mains transformer, the mainsvoltage is divided by approx. 85%
(standby transformer) to 15% (mains transformer). Thus the mains transformer delivers very low secondary voltage ?
power consumption is less than 100mW.
Via standby transformer and rectifiers 6209-6212 the supply voltage +C is substituted. The 5,6V regulator is still working
and so the microprocessor is kept running.
Y DC voltages +A, +B1/+B2, +C
These voltages supply the Super Class G amplifier, described later in this chapter.
The whole power supply is optimized for the special characteristic of this type of amplifier. For that reason several Otricky�
details have been applied to ensure optimal efficiency and symmetrical load to the mains transformer.
Generation of +A
Common full wave rectifying with bridge rectifier 6201, using 100% secondary winding of mains transformer (pin 9-15).
Generation of +B1/+B2
The power supply is designed to cover both, 2-channel and 4-channel application.
While for 2-channel application only one supply voltage +B1 is sufficient, 4-channel application requires an additional
supply part +B2 which supplies the Center/Surround-amplifiers and the +12V-regulator (current required by 4 amplifiers
would overload a single rectifier).
The supply for 2-channel versions consists of one full wave rectifier:
� 2 diodes of bridge rectifier 6201, with 6204/6205 for generation of +B1
- +B2 is connected in parallel with a bridge wire.
The supply for 4-channel versions consists of two separate full wave rectifiers:
� 2 diodes of bridge rectifier 6201, with 6204/6205 (for +B1) and
� 2 diodes of bridge rectifier 6201, with 6202/6203 (for +B2),
using approx. 70% secondary winding of mains transformer (pin 9-14 respectively pin 12-15).
As example for generation of +B2 see picture 1. |
ACEC
