For books I learnt a lot from Servicing TV and Video Equipment by Eugene Trundle. Although a it was too technical at the time when I bought it, as the years have gone by and my knowledge increased I've found it very useful. You can still buy the book from Amazon.
https://www.amazon.co.uk/Servicing-T...ideo+equipment
It might be worth checking in your local library. Mine used to keep servicing books like this but the reference section is not what it used to be!