Before Repairs; Protection Circuitry - Technics SA-EH670 Service Manual

2001 Matsushita Electric Industrial Co., Ltd. All rights reserved.
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1. Before Repairs

1. Turn off the power supply. Using a 10
both ends of power supply capacitors (C701, C703 and C702,
C704) in order to discharge the voltage.
2. Before turning the power supply on, after completion of repair,
slowly apply the primary voltage by using a power supply voltage
controller to make sure that the consumed current at 50 Hz in NO
SIGNAL mode should be shown below with respectto supply
voltage 230 V.
Power supply
voltage
Consumed current
50 Hz

2. Protection Circuitry

The protection circuitry may have operated if either of the following conditions is noticed:
- No sound is heard when the power is switched ON.
- Sound stops during a performance.
The functions of this circuitry is to prevent circuitry damage if, for example, the positive and
negative speaker connection wires are shorted, or if speaker systems with an impedance less
than the indicated rated impedance of this unit are used.
If this occurs, follow the procedures outlined below.
1. Switch OFF the power.
2. Determine the cause of the problem and correct it.
3. Switch ON the power once again.
Note:
When the protection circuitry functions, the unit will not operate
unless the power is first switched OFF and then ON again.
AC 230 V
70 ~ 300
mA
, 10 W resistor, connect
2