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2 14 Schematic Diagram---------------------------------------------28
14.1. D-AMP CIRCUIT, LED DRIVE CIRCUIT and
LED CIRCUIT (SE-FX70) ------------------------------ 28
15 Printed Circuit Board------------------------------------------30
15.1. D-AMP P.C.B., LED DRIVE P.C.B. and LED
P.C.B. (SE-FX70)----------------------------------------- 30
15.2. DIGITAL RECEIVER MODULE (RX) P.C.B.
(SE-FX70) and DIGITAL TRANSMITTER
MODULE (TX) P.C.B. (SH-TR70) -------------------- 31
16 Exploded View and Replacement Parts List-----------32
16.1. Exploded View and Mechanical Replacement
Parts List --------------------------------------------------- 32
16.2. Electrical Replacement Parts List -------------------- 36
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1 Safety Precautions
1.1. General Guidelines
1. When servicing, observe the original lead dress. If a short circuit is found, replace all parts which have been overheated or
damaged by the short circuit.
2. After servicing, see to it that all the protective devices such as insulation barriers, insulation papers shields are properly
installed.
3. After servicing, carry out the following leakage current checks to prevent the customer from being exposed to shock hazards.
(This Safety Precaution is applied only in U.S.A.)
1. Before servicing, unplug the power cord to prevent an electric shock.
2. When replacing parts, use only manufacturers recommended components for safety.
3. Check the condition of the power cord. Replace if wear or damage is evident.
4. After servicing, be sure to restore the lead dress, insulation barriers, insulation papers, shields, etc.
5. Before returning the serviced equipment to the customer, be sure to make the following insulation resistance test to prevent
the customer from being exposed to a shock hazard.
1.1.1. Leakage Current Cold Check
1. Unplug the AC cord and connect a jumper between the two prongs on the plug.
2. Measure the resistance value, with an ohmmeter between the jumpered AC plug and each exposed metallic cabinet part on
the equipment such as screwheads, connectors, control shafts, etc. When the exposed metallic part has a return path to the
chassis, the reading should be between 1MΩ and 5.2MΩ. When the exposed metal does not have a return path to the chas-
sis, the reading must be
1.1.2. Leakage Current Hot Check
1. Plug the AC cord directly into the AC outlet. Do not use an isolation transformer for this check.
2. Connect a 1.5kΩ, 10 watts resistor, in parallel with a 0.15μF capacitors, between each exposed metallic part on the set and a
good earth ground such as a water pipe, as shown in Figure 1.
3. Use an AC voltmeter, with 1000 ohms/volt or more sensitivity, to measure the potential across the resistor.
4. Check each exposed metallic part, and measure the voltage at each point.
5. Reverse the AC plug in the AC outlet and repeat each of the above measurements.
6. The potential at any point should not exceed 0.75 volts RMS. A leakage current tester (Simpson Model 229 or equivalent)
may be used to make the hot checks, leakage current must not exceed 1/2 milliamp. In case a measurement is outside of the
limits specified, there is a possibility of a shock hazard, and the equipment should be repaired and rechecked before it is
returned to the customer.
Figure. 1
1.2. Before Repair and Adjustment (SE-FX70)
This model uses switching mode power supply (SMPS) module to provide the necessary voltages for the Digital Receiver (SE-
FX70)
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 120 V, at 60 Hz in NO SIGNAL mode (at volume minimum) should be ~200 mA.
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
