Fairlight CMI Series IIx repair…. Part 1

So, I’ve been asked to fix a Fairlight series IIx, I don’t often do repairs but the chance to actually use one of these rare beasts was too much to turn down.

Now I have removed the cover on this before the picture, it’s sat on top.

This Fairlight died in the late 90s and has been left like it since, every time you power it on it blows the mains fuse, a 3.15A anti surge fuse.

So before power it up again, I removed all the cards, and disconnected all the internal power harnesses (floppy drives, etc). My concern is that something on one of the cards, keyboard(s) or screen is causing a problem. So I removed everything;

I checked all the fuses and they were all intact, except the mains fuse of course.

I then replaced the mains fuse and powered up again, now at this point I was half hoping it would blow (which means it’s a power supply problem) and half hoping it wouldn’t blow (meaning it would not be a power supply problem as they can be a night mare to debug).

And yup, it blew the mains fuse again.
So, we have a PSU problem, now thankfully this is a completely linear power supply, so whilst there are some high currents, it should be relatively easy to begin isolating parts of the power supply and working back from there.

But it’s dinner time now, so more another day.