Caution
Be sure no power is applied to the chassis or circuit, and observe all other safety precautions.
8. Minimize bodily motions when handling unpackaged replacement ES devices. (Otherwise harmless motion such as the
brushing together of your clothes fabric or the lifting of your foot from a carpeted floor can generate static electricity
(ESD)sufficient to damage an ES device).
4 Before Repair and Adjustment (Using Active Subwoofer)
Disconnect AC power, discharge Power Supply Capacitors C546~C549 through a 10
Ω
, 10 W resistor to ground.
DO NOT SHORT-CIRCUIT DIRECTLY (with a screwdriver blade, for instance), as this may destroy solid state devices.
After repairs are completed, restore power gradually using a variac, to avoid overcurrent.
Current consumption at AC 120 V, 60 Hz in NO SIGNAL mode should be ~ 1000 mA.
5 Protection Circuitry
The protection circuitry may have operated if either of the following conditions are noticed:
·
No sound is heard when the power is turned on.
·
Sound stops during a performance.
The function 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 the amplifier are used.
If this occurs, follow the procedure outlines below:
1. Turn off the power.
2. Determine the cause of the problem and correct it.
3. Turn on the power once again after one minute.
Note:
When the protection circuitry functions, the unit will not operate unless the power is first turned off and then on again.
6
SA-HT720P / SA-HT720PC
Summary of Contents for SA-HT720P
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