Maybe I am misunderstanding your post but there should be no voltage change across a fuse unless it is bad. Check the easy stuff first: fuse, loose connection, power supply is making the 12v. Corrosion can be cleaned with isopropyl alcohol is you sopt some.
4 months ago | 0
LearnToStargaze
20 year old filter wheel control board is showing 7 volts across the fuse (should be ~12) and the data line (RS422 I assume) is hot. Seems like a short somewhere. Any ideas what’s wrong?
4 months ago | [YT] | 23