- 3 -
SAFETY PRECAUTIONS
General Guidance
An
lsolation Transformer should always be used
during the
servicing of a receiver whose chassis is not isolated from the
AC power line. Use a transformer of adequate power rating as
this protects the technician from accidents resulting in personal
injury from electrical shocks.
It will also protect the receiver and it's components from being
damaged by accidental shorts of the circuitary that may be
inadvertently introduced during the service operation.
If any fuse (or Fusible Resistor) in this monitor is blown, replace
it with the specified.
When replacing a high wattage resistor (Oxide Metal Film
Resistor, over 1W), keep the resistor 10mm away from PCB.
Keep wires away from high voltage or high temperature parts.
Leakage Current Cold Check(Antenna Cold Check)
With the instrument AC plug removed from AC source, connect
an electrical jumper across the two AC plug prongs.
Place the AC switch in the on positioin, connect one lead of
ohm-meter to the AC plug prongs tied together and touch other
ohm-meter lead in turn to each exposed metallic parts such
as antenna terminals, phone jacks, etc.
If the exposed metallic part has a return path to the chassis,
the measured resistance should be between 1M
Ω
and 5.2M
Ω
.
When the exposed metal has no return path to the chassis
the reading must be infinite.
An other abnormality exists that must be corrected before the
receiver is returned to the customer.
IMPORTANT SAFETY NOTICE
Many electrical and mechanical parts in this chassis have special safety-related characteristics. These parts are identified
by in the Schematic Diagram and Replacement Parts List.
It is essential that these special safety parts should be replaced with the same components as recommended in this
manual to
prevent Shock, Fire, or other Hazards.
Do not modify the original design without permission of manufacturer.
Leakage Current Hot Check
(See below Figure)
Plug the AC cord directly into the AC outlet.
Do not use a line Isolation Transformer during this
check.
Connect 1.5K/10watt resistor in parallel with a 0.15uF capacitor
between a known good earth ground (Water Pipe, Conduit, etc.)
and the exposed metallic parts.
Measure the AC voltage across the resistor using AC
voltmeter with 1000 ohms/volt or more sensitivity.
Reverse plug the AC cord into the AC outlet and repeat AC
voltage measurements for each esposed metallic part. Any
voltage measured must not exceed 0.75 volt RMS which is
corresponds to 0.5mA.
In case any measurement is out of the limits sepcified, there
is possibility of shock hazard and the set must be checked
and repaired before it is returned to the customer.
Leakage Current Hot Check circuit
TOSHIBA OF CANADA LTD.
191 McNABB STREET, MARKHAM.
ONTARIO, L3R 8H2, CANADA
TEL : (905)470-5400
1.5 Kohm/10W
To Instrument's
exposed
METALLIC PARTS
Good Earth Ground
such as WATER PIPE,
CONDUIT etc.
AC Volt-meter
0.15uF
