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13 Schematic Diagram Notes
-----------------------------------31
14 Schematic Diagram --------------------------------------------- 33
14.1. D-AMP CIRCUIT ----------------------------------------- 33
14.2. ID SWITCH CIRCUIT, AC INLET CIRCUIT ------- 34
15 Printed Circuit Board ------------------------------------------ 35
15.1. D-AMP P.C.B., ID SW ITCH P.C.B., AC INLET
P.C.B.-------------------------------------------------------- 35
16 Exploded View and Replacement Parts List -----------37
16.1. Exploded View and Mechanical replacement Parts List --------------------------------------------------- 37
16.2. Electrical Replacement Parts List -------------------- 40
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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, ensure that all the protective devices such as insulation barriers, insulation papers shields are properly
installed.
3. After servicing, check for leak age current checks to prevent from being exposed to shock hazards.
1.1.1. Leakage Current Cold Check
1. Unplug the AC cord and connect a jumper between the two prongs on the plug.
2. Using an ohmmeter measure the resistance value, between the jumpered AC plug and each exposed metallic cabinet part on
the equipment such as screwheads, connectors, control shafts, et c. When the exposed metallic part has a return path to the
chassis, the reading should be between 1M Ω and 5.2 Ω. When the exposed metal does not have a return path to the chassis,
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 1.5k Ω, 10 watts resistor, in parallel with a 0.15 μF 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 a nd 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, le akage current must not exceed 1/2 milliamp. should the measurement is outside of
the limits specified, there is a possibilit y of a shock hazard, and the equipment s hould be repaired and re-checked before it i s
returned to the customer.
