Toshiba 40LV733G, Service Manual

Page: 13 / 66

10. Touch current check. (After completing the work, measure touch current to prevent an
electric shock.)
Plug the AC cord directly into the AC outlet. Do NOT use an isolation transformer
for this check.
Connect a measuring network for touch currents between each exposed metallic part
on the set and a good earth ground such as a water pipe.
The potential at any point (TOUCH CURRENT) expressed as voltage and
does not exceed the following value:
Product Safety Notice
Many electrical and mechanical parts in this chassis have special safety-related
Annex D
(normative)
Measuring network for TOUCH CURRENTS
Resistance values in orms ( Ω ).
Input resistance : 1 M Ω
Input capacitance : 200 pF
Frequency range : 15 Hz to 1 MHz and d.c. respectively
Note: Appropriate measures should be taken to obtain the correct value in case of non
sinusoidal waveforms.
The measuring instrument is calibrated by comparing the frequency factor of with the
solid line in figure F.2 of IEC 60990 at various frequencies. A calibration curve is
constructed showing the deviation of
from the ideal curve as a function of frequency.
TOUCH CURRENT = /500 (peak value).
V: Voltmeter or oscilloscope
(r.m.s. or peak reading)
The part or contact of a TERMINAL is not HAZARDOUS LIVE if:
Note: The limit values of = 0.35 V (peak) for a.c. and = 1.0 V for d.c. correspond to
the values 0.7 mA (peak) a.c. and 2.0 mA d.c.
a) The open-circuit voltage should not exceed 35 V (peak) a.c. or 60 V d.c. or, if a) is not
met.
b) The measurement of the TOUCH CURRENT shall be carried out in accordance with
IEC 60990, with the measuring network described in Annex D of this standard.
The TOUCH CURRENT expressed as voltages and , does not exceed the
following values:
- for a.c. :
= 35 V (peak) and = 0.35 V (peak);
- for d.c. : = 1.0 V