CEDIA ESPA EST Practice Test

Answer - B - In this case, the dimmer’s Thyristor is bad.

Key Takeaway: Dimmer controls can be harder to troubleshoot because there are several different types. In this case, if the lamp remains on even after disconnecting the neutral wire, the dimmer’s Thyristor is faulty. Replace the dimmer control. Thyristors act as bi-stable switches, conducting when their gate receives a current pulse, and continue to conduct for as long as they are forward biased.