These machines may be used for permissible purposes, or they may be used for haraam purposes, which is what usually happens, such as watching pictures of women who are clothed yet naked, or listening to music.
Hence it is not permissible to repair them unless that is done for one whom it is known or is thought most likely will use them for permissible purposes. But if it is known or is thought most likely that a person will use them for haraam purposes, it is not permissible to help him to fix his machine. Allaah says (interpretation of the meaning):
“but do not help one another in sin and transgression. And fear Allaah. Verily, Allaah is Severe in punishment”
The Standing Committee For Issuing Fatwas was asked the following question:
I work as an electronic engineer, and part of my work is fixing radios, TVs, VCRs and the like. I hope that you can advise me as to whether I should continue in this work, knowing that if I do not do this work I will miss out on a lot of experience and the profession for which I have been studying all my life, and I may suffer a lot of harm because of not doing this.
The evidence of sharee’ah, from the Qur’aan and Sunnah, indicates that the Muslim must strive to find a good source of income. So you have to look for work where your income will be good (i.e., halaal). As for earning a living from the work that you mention, this is not good, because these machines are usually used for haraam purposes.
From Fataawa al-Lajnah al-Daa’imah, 14/420.
And Allaah knows best.