Safety Check-Out - Sony SX-M700 Service Manual

2-10. SAFETY CHECK-OUT

After correcting the original service problem, perform the
following safety checks before releasing the set to the
customer.
Check that the set does not have leakage current in excess
of 0.5 mA when measured as described below.
All exposed conductive surfaces are to be tested for
leakage currents. The leakage currents from these surfaces
are to be measured to the grounded supply conductor
individually as well as collectively where simultaneously
accessible, and from one surface to another where
simultaneously accessible. These measurements do not
apply to terminals operating at voltages that are less than
30 volts.
The measurement circuit for the leakage current test is as
described below. The measurement instruments defined in
the following (a)-(d).
a) The meter is to have an input impedance of 1500 ohms
resistive shunted by a capacitance of 0.15 microfarad.
b) The meter is indicate 1.11 times the average of the full
wave rectified composite waveform of voltage across
the resistor or current through the resistor.
c) Over a frequency range of 0-100 kilohertz the
measurement circuitry is to have a frequency response
(ratio of indicated to actual value of current) that is
equal to the ratio of the impedance of a 1500 ohm
resistor shunted by a 0.15 microfarad capacitor to 1500
ohms. At an indication of 0.5 milliampere, the
measurement is to have an error of not more than 5
percent at 60 Hz.
d) Unless the meter is being used to measure current from
one part of the equipment to another, the meter is to be
connected between the accessible parts and the
grounded supply conductor.
SX-M700
The test sequence is as follows:
a) With switch S1 open, the equipment is to be connected
to measuring circuit. Leakage current is to be
measured using both positions of switch S2, and with
the equipment switching devices in all of their intended
operating positions.
b) Switch S1 is then to be closed, energizing the
equipment, and within 5 seconds the leakage current is
to be measured using both positions of switch S2, and
with the equipment switching devices in all their
intended operating position.
c) Leakage current is to be monitored until thermal
stabilization. Both positions of S2 are to be used in
determining this measurement.
Leakage current measurement circuits
Equipment intended for connection to a 120 volt power supply.
Equipment intended for connection to a 3-wire, grounded neutral
power supply, as illustrated above.
Equipment intended for connection to a 3-wire, grounded neutral
power supply, as illustrated above.
A. Probe with shielded lead.
B. Separated and used as clip when measuring currents from
one part of equipment to another.
2-19(E)