Panasonic sc htb688e service manual
This is the 35 pages manual for panasonic sc htb688e service manual.
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Extracted text from panasonic sc htb688e service manual (Ocr-read)
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2 TABLE OF CONTENTS PAGE 1 Safety Precautions ----------------------------------------------- 3 1.1. General Guidelines ----------------------------------------- 3 1.2. Leakage Current Cold Check ----------------------------- 3 1.3. Leakage Current Hot Check (See Figure 1.) --------- 3 1.4. Protection Circuitry-------------------------------------------\ 3 2 Warning -------------------------------------------------------------- 4 2.1. Prevention of Electrostatic Discharge (ESD) to Electrostatically Sensitive (ES) Devices ------------ 4 2.2. Caution for AC Cord (For EB) ----------------------------- 5 2.3. Service Caution Based on Legal Restrictions --------- 6 3 Service Navigation ---------------------------------------------- 7 3.1. Service Information ----------------------------------------- 7 4 Speci ications ----------------------------------------------------- 8 5 Location of Controls and Components ------------------- 10 6 Service Mode ------------------------------------------------------ 13 7 Troubleshooting Guide ----------------------------------------- 15 7.1. Main Unit (SU-HTB688) ----------------------------------- 15 7.2. Active Subwoofer (SB-HWA688) ------------------------ 20 8 Wiring Connection and Voltage Data ---------------------- 22 8.1. Main Unit (SU-HTB688) ----------------------------------- 22 8.2. Active Subwoofer (SB-HWA688) ------------------------ 24 9 Service Fixture & tools ----------------------------------------- 26 10 Disassembly and Assembly Instructions --------------- 27 10.1.Disassembly Flow Chart --------------------------------- 27 10.2.P.C.B. Positions -------------------------------------------- 28 10.3.Disassembly Procedure of Main Unit (SU-HTB688) ------------------------------------------ 29 10.4.Disassembly Procedure of of Active Subwoofer (SB-HWA688) --------------------------------- 33 11 Measurements and Adjustments -------------------------- 35 11.1.Service Position -------------------------------------------- 35
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3 1 Safety Precautions 1.1. General Guidelines 1. IMPORTANT SAFETY NOTICE There are special components used in this equipment which are important for safety. These parts are marked by in the Schematic Diagrams, Circuit Board Layout, Exploded Views and Replacement Parts List. It is essential that these critical parts should be replaced with manufacturers specified parts to prevent X-RADIATION, shock, fire, or other hazards. Do not modify the original design without permission of manufac\ turer. 2. An Isolation Transformer should always be used during the servicing of AC Adaptor whose chassis is not isolated from the AC power line. Use a transformer of adequate power rating as this protects the technician from accidents resulting in personal injury from electrical shocks. It will also protect AC Adaptor from being damaged by accidental shorting that may occur during servicing. 3. 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. 4. After servicing, see to it that all the protective devices such as insulation barriers, insulation papers shields are properly installed. 5.After servicing, make the following leakage current checks to prevent \ the customer from being exposed to shock hazards. 1.2. 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. Wh\ en the exposed metallic part has a return path to thechassis, the reading should be between 1 MΩ and 5.2 MΩ. When the exposed metal does not have a return path to the chas-sis, the reading must be infinity. 1.3. Leakage Current Hot Check (See Figure. 1) 1. Plug the AC cord directly into the AC outlet. Do not use an isolation transformer for this check. 2. Connect a 1.5 kΩ, 10 W resistor, in parallel with a 0.15 μF capacitor, between each exposed metallic part on the set and a good earth ground, as shown in Figure. 1. 3. Use an AC voltmeter, with 1 kΩ/V 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 V RMS. A leakage current tester (Simpson Model 229 or equivalent) maybe used to make the hot checks, leakage current must not exceed 1/2 mA. In case a measurement is outside of the limitsspecified, there is a possibility of a shock hazard, and the equipment should be repaired and rechecked before it is returned tothe customer. 1.4. Protection Circuitry The protection circuitry may have operated if either of the following co\ nditions 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 areshorted, 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 of f and then on again Figure. 1