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SAFETY
SAFETY PRECAUTIONS
WARNING: The following precautions must be observed. ALL PRODUCTS 1. Before any service is performed on the chassis an isolation transformer should be inserted between the power line and the product. 2. When replacing the chassis in the cabinet, ensure all the protective devices are put back in place. 3. When service is required, observe the original lead dressing. Extra precaution should be taken to ensure correct lead dressing in any high voltage circuitry area. 4. Many electrical and mechanical parts in SANYO products have special safety related characteristics. These characteristics are often not evident from visual inspection, nor can the protection afforded by them necessarily be obtained by using replacement components rated for higher voltage, wattage, etc. Replacement parts which have these special safety characteristics are identified by marking with a ! on the schematics and the replacement parts list. The use of a substitute replacement component that does not have the same safety characteristics as the SANYO recommended replacement one, shown in the parts list, may create electrical shock, fire, X-radiation, or other hazards. 5. Always replace original spacers and maintain lead lengths. Furthermore, where a short circuit has occurred, replace those components that indicate evidence of overheating. 6. Insulation resistance should not be less than 2M ohms at 500V DC between the main poles and any accessible metal parts. 7. No flashover or breakdown should occur during the dielectric strength test, applying 3kV AC or 4.25kV DC for two seconds between the main poles and accessible metal parts. 8. Before returning a serviced product to the customer, the service technician must thoroughly test the unit to be certain that it is completely safe to operate without danger of electrical shock. The service technician must make sure that no protective device built into the instrument by the manufacturer has become defective, or inadvertently damaged during servicing. CE MARK 1. SANYO products may contain the CE mark on the rating plate indicating that the product contains parts that have been specifically approved to provide electromagnetic compatibility to designated levels. When replacing any part in this product, please use only the correct part itemised in the parts list to ensure this standard is maintained, and take care to replace lead dressing to its original state, as this can have a bearing on the electromagnetic radiation/immunity. PICTURE TUBE 1. The line output stage can develop voltages in excess of 25kV; if the E.H.T. cap is required to be removed, discharge the anode to chassis via a high value resistor, prior to its removal from the picture tube. 2. High voltage should always be kept at the rated value of the chassis and no higher. Operating at higher voltages may cause a failure of the picture tube or high voltage supply, and also, under certain circumstances could produce X-radiation levels moderately in excess of design levels. The high voltage must not, under any circumstances, exceed 29kV on the chassis (except for projection Televisions). 3. The primary source of X-radiation in the product is the picture tube. The picture tube utilised for the above mentioned function in this chassis is specially constructed to limit X-radiation. For continued X-radiation protection, replace tube with the same type as the original SANYO approved type 4. Keep the picture tube away from the body while handling. Do not install, remove, or handle the picture tube in any manner unless shatterproof goggles are worn. People not so equipped should be kept away while picture tubes are handled LASERS If the product contains a laser avoid direct exposure to the beam when the cover is open or when interlocks are defeated or have failed.
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SAFETY AND ISOLATION
Under no circumstances should any form of repair or maintenance be attempted by any person other than a competent technician or engineer. Most of the circuitry on the chassis is isolated from the AC supply by T801, C831, R821, IC802 and 6mm air gaps. To maintain this safety factor ensure that, after repair, any gaps or leakage paths are not reduced by protruding wires etc., following component replacement NOTE: although the output supply paths from the power supply section are isolated from the incoming AC supply, the bridge rectifier and the control and regulation circuits are not isolated. Therefore, when servicing the power supply section of the chassis, the AC supply should be connected via an isolating transformer of at least 200 watts rating. The power supply section remains charged with respect to chassis for 3060 seconds after switching off. Care should be taken to avoid touching the power supply area of the chassis during this time. Components marked ! in the parts list are safety approved types and should be replaced only with components supplied or approved by our Service Department. It is also recommended that components not marked with the safety
symbol should be replaced with parts of the type originally fitted. This applies particularly to those resistors which are `stood off' the printed circuit boards. Chassis Operation and Alignment The majority of chassis functions are implemented within ICXXX and its associated circuitry. These are controlled by the micro-controller ICXXY via the I²C bus, a two wire bus (SDA, Serial Data and SCL, Serial Clock). The microcontroller contains twenty adjustable parameters between 0013 (hex) which are used to control the functions of ICXXZ . (See Adjustments for further details on how to adjust or reset these.) Handling Precautions - Static Electrical Charge The receiver contains devices which may be damaged by static electrical charges during handling. To avoid damage, soldering irons should be earthed, and service personnel should, ideally, wear wrist straps earthed through a 1M ohm resistor. If the latter is not practical, they should discharge themselves by touching an earthed point. Sensitive static devices should be packed in suitable conductive containers.
IMPORTANT: although the receiver chassis is isolated, the AC supply should be disconnected during service replacement of such static devices.
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