Re: Proper fuse for KL-4820 power supply
It depends on where the AC is in it's cycle when you turn it on as to whether it blows the fuse or not. The instantaneous in rush is highest at the peak and lowest at zero crossing. If you want to almost never blow a small fuse, install a zero-crossing turn on relay. For that power supply I would probably use a 15 amp, D curve dual breaker.
If it is now constantly blowing fuses with no load, then I would start looking at the bridge diode or filter caps, it may have failed. It would not be the first time I have seen one of those fail.
Jim Dawson
Sandy, Oregon, USA