4
1.2.
Before Repair and Adjustment
Disconnect AC power to discharge AC capacitor (in SMPS Module) as indicate below diagram through a 10
Ω
, 10 W resistor to
ground.
Figure 1-2
Caution:
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 127 V, 60 Hz in Power ON, FM Tuner at volume minimal mode should be ~ 750 mA (LM).
1.3.
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.
