1-5. Safety Check-Out
After correcting the original service problem, perform the following safety
checks before releasing the set to the customer:-
1) Check the area of your repair for unsoldered or poorly soldered connections.
Check the entire board surface for solder splashes and bridges.
2) Check the inter board wiring to ensure that no wires are pinched or
contact high-wattage resistors.
3) Check all control knobs, shields, covers, ground straps and mounting
hardware have been replaced. Be certain you have replaced all the
insulators.
4) Look for unauthorized replacement parts, particularly transistors that were
installed during a previous repair. Point them out to the customer and
recommend them replacement.
5) Look for parts which show obvious signs of deterioration even though
functioning. Point them to the customer and recommend for replacement.
6) Check the line cords for cracks and abrasion. Recommend the replacement
of any such line cord to the customer.
7) Check the antenna terminals, metal trim, metalized knobs, screws and all
other exposed metal parts for AC leakage. Check leakage test as described
next.
8) For safety reasons, repairing the Power board and/or Inverter board is
prohibited.
1-6. Leakage Test.
(To protect electric shock when customer touch the terminal.). Leakage current
can be measured by V: Voltmeter or oscilloscope (r.m.s or peak reading).
Stabilized power supply instrument and isolated voltage transformer:
Use too much current capacity and isolated voltage transformer does not need
to use stabilized power supply equipment.
Specification of RMS voltmeter: Input resistance > 1 Mohm, Input capacitance <
200 pF, Frequency range: 15 Hz – 1MHz . Refer Figure 2. Isolated type volt -
meter (FLUKE 8921A etc *1).
*1 Not use FLUKE 8920A that connected to protective earth by diode.
# Leakage current of measurement instrument is less than 10μArms when under
test equipment AC plug is opened.
# Set up the following condition and turn on the set. Applied voltage: Nominal
input voltage (Description on Nameplate).
# Measure the leakage current between one phase conductor and neutral for
terminal A and terminal B.
Read rms value, and then calculate to peak value PEAK VALUE =√2 RMS
VALUE.
Comply with the following requirement.
Class II equipment (2-pin plug): for each terminal, the worst value of
measurement must not exceed AC 350uA peak).
Note: including AC adaptor, AC adaptor/DC operated unit combination.
Figure 2 – Measuring network for Leakage Current
10
SAFETY NOTES
SYSSET
2023/11/2806:39:49(GMT+09:00)
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