I want to add a second screen to my Imac and I found a Cinema Display (ADC). I went to see the screen and i connect it to my Macbook to test if it works. The guy who sold the screen had an ADC to DVI adapter and I bought an DVI to thunderbolt connector. It didn't work. He also tried to connect it to his Imac and still the screen didn't work. Is it even possible to connect the screen to an Imac?
Is it the Apple version of the DVI to ADC adapter? The signals from a Mini DisplayPort (or Thunderbolt) to DVI adapter may be weaker than normal DVI signals. The Apple DVI to ADC adapter amplifies the DVI signals, so can work with signals that are too weak for non-Apple adapters.
An ACTIVE Mini DisplayPort to DVI adapter may produce stronger DVI signals.