[IQChallenged]

When I was ordering the components for my DIY CNC router power supply I knew nothing. Everything thing I ordered was a gamble. To compound the danger- some of the people I ordered components from knew nothing. They just ordered things from eBay and hoped to resell it at a profit. They, themselves, may have never even built a machine. I got lucky because almost everything I bought worked. I have a really great machine. But little by little I hope to find little things that might be improved.

I recently rebuilt my electrics box. I kept blowing fuses. The little glass fuse that kept blowing was about $2.50 each. They're just little glass fuses. There's something about fuses of that amperage. They're a little but shorter than what you might find in automotive use and low on the amp rating. Somehow that combination makes them very expensive. As it turned out there was nothing wrong with my system. The blowing was the result of the 110v power cord being a little loose. That looseness would create a little momentary resistance which would cause the fuse to blow. By the time I figured it out I had run through an expensive box of fuses. Now- as I contemplate buying another box- I wonder if I even need a fuse at that point. So I'm hoping that one of you can tell me. The drivers are fused elsewhere. On the left lower corner of my drawing you will see the 4a fuse I'm considering doing away with. Thanks for any advice.

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[H.O]

Hi,
I would definetly keep the fuse on the primary side. What kind of fuse is that if you're paying $2.50 each for them? By the looks of it it's just an ordinary 5X20mm fuse, Digikey part number 507-1252-ND for example, 4A slow blow, $0.41 in single quantites.

If it always blows on power-up it may be due to the high inrush current of transformer in the power supply, what's the power rating of transformer (hpw many VA's)?

[yngndrw]

I second what H.O said, over here we have fused plugs on every appliance.

You should be using a "slow blow" if you aren't already.

[IQChallenged]

Hi,
I would definetly keep the fuse on the primary side. What kind of fuse is that if you're paying $2.50 each for them? By the looks of it it's just an ordinary 5X20mm fuse, Digikey part number 507-1252-ND for example, 4A slow blow, $0.41 in single quantites.

If it always blows on power-up it may be due to the high inrush current of transformer in the power supply, what's the power rating of transformer (hpw many VA's)?

Thanks to all responders. I will use the digikey source at $0.41. With regard to the question about VAs- I wouldn't have a clue. Don't even know how to find out. Anyhow the problem disappeared when I made it a point to have the plug tight.