Toshiba 42L7453D, Service Manual

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8. Always ensure that all internal wirings are in accordance before re-assembling the
external casing after a repairing completed. Do not allow internal wiring to be pinched
by cabinets, panels, etc. Any error in reassembly or wiring can result in electrical
leakage, flame, etc., and may be hazardous.
9. NEVER remodel the product in any way. Remodeling can result in improper operation,
malfunction, or electrical leakage and flame, which may be hazardous.
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.
Annex D
(normative)
Measuring network for TOUCH CURRENTS
Resistance values in orms ( Ω ).
V: Voltmeter or oscilloscope
(r.m.s. or peak reading)
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).