Safety Precautions - Panasonic WJ-HDE300 Service Manual

PRODUCT COMPLIES WITH DHHS RULES 21 CFR SUB-
CHAPTER J APPLICABLE AT DATE OF MANUFACTURE

SAFETY PRECAUTIONS

GENERAL GUIDELINE
1. When service is required, observe the original lead
dress. Components, wires or cables that indicate
evidence of overheating or other electrical or mechanical
damage should be replaced.
2. After servicing see to that all the protective devices, such
as insulation tape, shields must be properly installed.
3. After servicing, make the following leakage current
checks to prevent the customer from being exposed to
shock hazards.
LEAKAGE CURRENT COLD CHECK
1. Unplug the AC cord and connect a jumper between the
two prongs on the plug.
2. Measure the resistance value, with an ohmmeter,
between the jumpered AC plug and each exposed
metallic cabinet par t on the equipment such as
screwheads, connectors, control shafts, etc.
When the exposed metallic part has a return path to the
chassis, the reading should be between 1M Ω and 5.2M
Ω. When the exposed metal does not have a return path
to the chassis, the reading must be ∞ (infinity).
Any resistance value below this range indicates an
abnormality which requires corrective action.
3. Repeat the test with the AC switch in the "OFF" position.
AC OUTLET
DEVICE
UNDER
TEST
ADAPTOR
AC PLUG
Ground Lead Disconnected during safety check.
Fig. 1 Leakage Current Hot Check
LEAKAGE CURRENT HOT CHECK
1. Plug the AC cord directly into adaptor socket and plug
adaptor into the AC outlet. Do not use an isolation
transformer for this check.
2. Connect a 1.5k Ω/10W resistor, paralleled by 0.15 µF
capacitor, between each exposed metallic part on the
unit and a good earth ground such as a water pipe, as
shown in Figure 1.
3. Use an AC voltmeter, with 1000Ω/volt or more sensitivity,
to measure the potential across the resistor.
4. Check all exposed metallic parts of the cover (BNC
connector,
Screwheads, Metallic overlays, etc.), and measure the
voltage at each point.
5. Reverse the AC plug in the AC plug adaptor and re-peat
each of the above measurements.
6. The potential at any point should not exceed 0.75 V
RMS.
A leakage current tester (SIMPSON MODEL 229 or
equivalent) may be used to make the hot checks.
Leakage current must not exceed 0.5 milliampere.
In case a measurement is outside of the limits specified,
there is a possibility of a shock hazard, and corrective
action must be taken before returning the instrument to
the customer.
AC VOLTMETER
1.5kΩ
0.15µF
Test all exposed
metal parts
Handle bracket, Metallic cabinet,
Water Pipe
(Earth Ground)