Toshiba 37WL58A, Service Manual

Page: 4 / 127

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Annex D
(normative)
Measuring network for TOUCH CURRENTS
Resistance values in ohms (
Ω Ω
Ω Ω
Ω
)
V: Voltmeter or oscilloscope
(r.m.s. or peak reading)
Input resistance:
>
=
1 M
Ω Ω Ω Ω 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 U
2
with the solid line in figure F.2 of
IEC 60990 at various frequencies. A calibration curve is constructed showing the deviation of U
2
from the ideal
curve as a function of frequency.
TOUCH CURRENT = U
2
/500 (peak value).
Many electrical and mechanical parts in this chassis have special safety-related characteristics. These characteris-
tics are often passed unnoticed by a visual inspection and the protection afforded by them cannot necessarily be
obtained by using replacement components rated for higher voltage, wattage, etc. Replacement parts which have
these special safety characteristics are identified in this manual and its supplements; electrical components having
such features are identified by the international hazard symbols on the schematic diagram and the parts list.
Before replacing any of these components, read the parts list in this manual carefully. The use of substitute replace-
ment parts which do not have the same safety characteristics as specified in the parts list may create shock, fire, or
other hazards.
Fig. D.1
A
B
Test TERMINALS
R
b
=
500
Ω
R
b
=
1500
Ω
10 k
Ω
C
b
=
0.22
µ
F
0.022
µ
F
V
U
1
U
2
(V)
IEC 802/96
PRODUCT SAFETY NOTICE