I’m trying to change a dead component in my ATX power supply, the component is labeled “3866A”. I can’t find any datasheets or the component it self in the internet can any one help me please to find it, or suggest me a similar one.

 

Might possibly be 2SC3866, now obsolete.

 

I’m trying to change a dead component in my ATX power supply, the component is labeled “3866A”. I can’t find any datasheets or the component it self in the internet can any one help me please to find it, or suggest me a similar one.

If you don't know what it is then how do you know it is faulty?