SAFETY INSTRUCTION

WARNING: BEFORE SERVICING THIS CHASSIS, READ THE "SAFETY PRECAUTION" AND "PRODUCT SAFETY NOTICE" INSTRUCTIONS BELOW.

Safety Precaution

WARNING: SERVICING SHOULD NOT BE ATTEMPTED BY ANYONE UNFAMILIAR WITH THE NECESSARY PRECAUTIONS ON THIS RECEIVER. THE FOLLOWING ARE THE NECESSARY PRECAUTIONS TO BE OBSERVED BEFORE SERVICING THIS CHASSIS.

  1. An isolation transformer should be connected in the power line between the receiver and the AC line before any service is performed on the receiver.
     
  2. Always disconnect the power plug before any disassembling of the product. It may result in electrical shock.
     
  3. When replacing a chassis in the cabinet, always be certain that all the protective devices are put back in place, such as nonmetallic control knobs, insulating covers, shields, isolation resistor-capacitor network, etc.
     
  4. Always keep tools, components of the product, etc away from the children, These items may cause injury to children.
     
  5. Depending on the model, use an isolation transformer or wear suitable gloves when servicing with the power on, and disconnect the power plug to avoid electrical shock when replacing parts. In some cases, alternating current is also impressed in the chassis, so electrical shock is possible if the chassis is contacted with the power on.
     
  6. Always use the replacement parts specified for the particular model when making repairs. The parts used in products require special safety characteristics such as inflammability, voltage resistance, etc. therefore, use only replacement parts that have these same characteristics. Use only the specified parts when the mark is indicated in the circuit diagram or parts list.
     
  7. Parts mounting and routing dressing of  wirings should be the same as that used originally. For safety purposes, insulating materials such as isolation tube or tape are sometimes used and printed circuit boards are sometimes mounted floating. Also make sure that wirings is routed and clamped to avoid parts that generate heat and which use high voltage. Always follow the manufactured wiring routes / dressings.
     
  8. Always ensure that all internal wirings are in accordance before re-assembling the external casing after a repairing completed. Do not allow internal wiring to be pinched by cabinets, panels, etc. Any error in reassembly or wiring can result in electrical leakage, flame, etc., and may be hazardous.
     
  9. NEVER remodel the product in any way. Remodeling can result in improper operation, malfunction, or electrical leakage and flame, which may be hazardous.
     
  10. Touch current check. (After completing the work, measure touch current to prevent an electric shock.)
  • Plug the AC cord directly into the AC outlet. Do NOT use an isolation transformer for this check.
  • Connect a measuring network for touch currents between each exposed metallic part on the set and a good earth ground such as a water pipe.
     

    Annex D
    (normative)

    Measuring network for TOUCH CURRENTS



    Resistance values in orms (Ω).

    V:   Voltmeter or oscilloscope
    (r.m.s. or peak reading)

    Input resistance : 1 MΩ
    Input capacitance : 200 pF
    Frequency range : 15 Hz to 1 MHz and d.c. respectively

    Note: Appropriate measures should be taken to obtain the correct value in case of non sinusoidal waveforms.

    The measuring instrument is calibrated by comparing the frequency factor of with the solid line in figure F.2 of IEC 60990 at various frequencies. A calibration curve is constructed showing the deviation of from the ideal curve as a function of frequency.

    TOUCH CURRENT = / 500 (peak value).

  • The potential at any point (TOUCH CURRENT) expressed as voltage and does not exceed the following value:
     
    The part or contact of a TERMINAL is not HAZARDOUS LIVE if:
    a)   The open-circuit voltage should not exceed 35 V (peak) a.c. or 60 V d.c. or, if a) is not met.
    b)  

    The measurement of the TOUCH CURRENT shall be carried out in accordance with IEC 60990, with the measuring network described in Annex D of this standard.

    The TOUCH CURRENT expressed as voltages and , does not exceed the following values:
    - for a.c. : = 35 V (peak) and = 0.35 V (peak);
    - for d.c. : = 1.0 V

    Note: The limit values of = 0.35 V (peak) for a.c. and = 1.0 V for d.c. correspond to the values 0.7 mA (peak) a.c. and 2.0 mA d.c.