Therefore, the owners corporation has the duty to maintain common property, hence the OC obliged to fix the tv system.
Not strictly true. Paragraph 3 of Section 106 of the NSW Act, “Duty of owners corporation to maintain and repair property”, says this:
This section does not apply to a particular item of property if the owners corporation determines by special resolution that—
(a) it is inappropriate to maintain, renew, replace or repair the property, and
(b) its decision will not affect the safety of any building, structure or common property in the strata scheme or detract from the appearance of any property in the strata scheme.
In other words, the owners corp could decide by special resolution not to replace or repair the TV antenna wiring and if more than 75 per cent of owners (or those voting at a general meeting) agree, then the system could be dumped or altered.