Philips FW-C50/37, Руководство по обслуживанию

Страница: 11 / 132

2.
LEAKAGE CURRENT CHECKS
VCR SAFETY NOTES
FIRE & SHOCK HAZARD (VCR)
1. Be sure that all components are positioned in such a way to avoid possibility of shorts to adjacent
components. This is especially important on those chassis which are transported to and from the repair
shop.
2. Always replace all protective devices such as insulators and barriers after working on a set.
3. Check for damaged insulation on wires including the ac cord.
4. Check across-the-line components for damage and replace if necessary.
5. After re-assembly of the unit, always perform an ac leakage test on the exposed metallic parts of the
cabinet such as the knobs, antenna terminals, etc. to be sure the set is safe to operate without danger of
electrical shock.
Do not use a line isolation transformer during this test. Use an ac voltmeter
having 5000 ohms per volt or more sensitivity in the following manner: Connect a 1500 ohm 10 wan
resistor, paralleled by 0.15 MFD ac type capacitor, between a known good earth ground (water pipe,
conduit, etc.) and the exposed metallic parts, one at a time. Measure the ac voltage across the
combination 1500 ohm resistor and 0.15 MFD capacitor. Reverse the ac plug on the set and repeat ac
voltage measurements again for each exposed metallic part. Voltage measured must not exceed O.6
volts R.M.S. This corresponds to 0.4 milliamp ac. Any value exceeding this limit constitutes a potential
shock hazard and must be corrected immediately.
GENERAL