Use digital TV set-top box with due caution to ensure safety -
CHOICE # 380 (June 16, 2008)
PDF version
In collaboration with the Electrical
and Mechanical Services Department (EMSD), the Consumer Council has
released a test report on the safety of this new addition of
household electrical appliance.
This followed public concern that
some of the models available in the market were allegedly found to
hot up considerably whilst in use.
The test was conducted on 10 samples
in accordance with the IEC60065 standard. All were shown to comply
with the IEC standard on temperature rise. 6 models were rated to
achieve full score in overall safety on a 5-point rating.
4 samples, however, were found to be
less than perfect: 3 samples scored 4.5 points while 1 sample
received 3.5 points.
The safety rating was based on:
construction (40%), protection against electric shock (25%),
resistance to heat (20%), temperature rise (10%) and marking and
instructions (5%).
The principal safety deficiencies
detected in the 4 models included:
- The insulated internal wire could come to be in contact with
the accessible metal enclosure. In the event of insulation failure,
it may pose risk of current leakage.
- Inappropriate fixing of the PCB (circuit board) by the earthing
terminal screw.
- The internal component could be touched if replaced by a longer
screw.
- Only one layer of insulating tape to separate the primary and
secondary windings of the switching transformer.
- The creepage distances between live and neutral printed
circuits in the PCB is slightly less than the safety
requirements.
The EMSD has requested the
manufacturers concerned to rectify such deficiencies. The
manufacturers have responded positively to improve their
products.
Nonetheless, consumers are advised to
be cautious in using set-top boxes for digital TV reception -
whether or not the product could totally pass the safety test.
Important cautions to heed include:
- Place the set-top box in a well-ventilated area clear of such
household items as flower vase that could accidentally spill water
into the device.
- It is normal that set-top box when in operation will generate
heat and rise in temperature. But should the external casing become
scalding hot to touch or other abnormal conditions arise such as
smoke emission and burning smell, stop the use immediately and cut
off the electricity supply.
- Do not clean with a wet cloth; use a dry cloth or a mini vacuum
cleaner to remove dust.
- If the set-top box is not expected to be in use for a long
time, do not put it on standby mode, cut off the electricity supply
completely.
In the first 5 months of this year,
the Consumer Council has received some 36 cases of complaints over
set-top boxes.
Some were related to door-to-door
illicit sale activities by salesmen claiming to be staff of the
Housing Department. The salesmen were allegedly spreading the
rumour that the existing four free analogue TV channels would soon
be terminated and that new set-top boxes would need to be installed
for free television reception.
There is no truth in such
allegations. While the Government has set 2012 as a target to
switch off the existing analogue TV service, it is a tentative
target. The Government will take into account the actual market
conditions and give sufficient prior notice to the public before
deciding on the exact timing. The existing analogue service will
continue to be provided until the formal announcement by
Government.
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