Wells-Gardner Electronics Corporation
1.SAFETY PRECAUTION:
WARNING: Service should not be attempted by anyone unfamiliar with the necessary precautions on this unit. The following precautions are necessary during servicing.
1-1 Some parts, such as a picture tube in this unit, have special safety-related characteristics for X-RAY RADIATION protection.
For continued safety, the parts replacement should be undertaken referring to below article (1-2 and 1-5).
1-2 Many electrical mechanical parts in this unit have special safety-related characteristics for protection against shock hazard and others. These characteristics are often passed unnoticed by visual inspection and the protection afforded by them cannot necessarily be obtained by using replacement components rated for higher voltage, wattage, etc. Replacement parts which have these special characteristics are identified in the manual and supplements by shading on the schematic diagram and the parts list. Before replacing any of these components, read the parts list in this manual carefully.
1-3 When replacing the chassis in the cabinet, always be certain that all the protective devices are installed properly, such as insulating covers, strain relief, etc.
1-4 Before replacing the back cover of the set, thoroughly inspect the inside of the cabinet to see that no stray parts or tools have been left inside.
1-5 Before returning the set to the customer, always perform an AC leakage current check on the exposed metallic parts of the cabinet, such as terminal, screwheads, metal overlays, control shafts, etc. To insure the set is safe to operate without danger of electrical shock, plug the AC line cord directly into a 120V AC outlet (do not use a line isolation transformer during this check). Use an AC voltmeter having 5000 ohms per volt or more sensitivity in the following manner. Connect a 1500 ohm, 10 watt resistor, parallel with a (0.15uF) capacitor. Reverse the AC plug in the AC outlet and repeat the AC voltage measurements for each exposed metallic part. Voltage measured must not exceed 0.3V RMS. This corresponds to 0.2mA AC, any value exceeding this limit constitutes a potential shock hazard and must be corrected immediately.
