in the US, it depends on what state you are in. some states have licensing for TV technicians (MA for sure, possibly NY and CA as well) i know in MA, that TV techs require a tech license to work on TVs, and shop owners require a Master's license, but there are (or were, i have been in colorado for 20 years) no licenses required for repairing audio equipment or anything else... just for TV repair. it depends on the state (and whether or not that particular state government is greedy for taxes and fees).