I understand that my father will be happy if I buy a color tv for him as the existing one is out-of-order. Though he did not ask me directly to buy this for him, my understanding is that he will be very happy if I would give him a new tv .My father spends much of his time watching tv to pass his loneliness.
But I don't want to give him such a thing which will be a source of sin for him and me as well (as the money is mine). Also, my father is not in such a state of having religious knowledge that I may convince him that watching tv is a sinful act.
Please advise me whether I should give him a tv to make him happy or refrain.

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

A tv set could be used for a good or an evil purpose.

However, evil and mischief are predominant in it. It is known in religion that a Muslim should not help a fellow Muslim in sin. Allah says: "Help you one another in Al­ Birr and At-Taqwa (virtue, righteousness and piety); but do not help one another in sin and transgression. (Al-Ma'idah 5:2)

Therefore, since your father does not mind what he watches on tv whether Halal or Haram, we do not consider it permissible for you to buy a television for him even if he asks you to do so, let alone if he does not ask you to do so.

Allah knows best.