Philips FW-C50/37, Service Manual

Page: 5 / 132

jumper from the ac line cord.
LEAKAGE CURRENT HOT CHECK
1. Do not use an isolation transformer for this test. Plug the completely reassembled receiver directly
into the ac outlet.
2. Connect a
1.5k, 1OW resistor
paralleled by a
0.15uF. capacitor
between each exposed
metallic cabinet part and a
good earth ground
such as a water pipe, as shown below.
3. Use an ac voltmeter with at least 5000 ohms/volt sensitivity to measure the potential across the
resistor.
4.
The potential at any point should not exceed 0.75 volts .
A leakage current tester may be
used to make this test; leakage current must not exceed 0.5milliamp. If a measurement is outside of the
specified limits, there is a possibility of shock hazard. The receiver should be repaired and rechecked
before returning it to the customer.
5
. Repeat the above procedure with the ac plug reversed.
(Note: An ac adapter is
necessary when a polarized plug is used. Do not defeat the polarizing feature of the plug.)
OR
With the instrument completely reassembled, plug the AC line cord directly into a 120V AC outlet.
(Do
not use an isolation transformer during this test.)
Use a leakage current tester or a
metering system that complies with American National Standards Institute (ANSI) C101.1 Leakage
Current for Appliances and Underwriters Laboratories (UL) 1410, (50.7).
With the instrument
AC switch first in the on position and then in the off position, measure from a
known earth ground (metal water pipe, conduit, etc.) to all exposed metal
parts of the instrument (antennas, handle brackets, metal cabinet, screw
heads, metallic overlays, control shafts, etc.), especially any exposed metal
parts that offer an electrical return path to the chassis. Any current
measured must not exceed 0.5 milliamp. Reverse the instrument power cord
plug in the outlet and repeat the test. See graphic below.