68kMLA Classic Interface

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Replacing dead/blown fuses on Mac analog boards/power supplies

Posted by: joshc on 2020-04-12 08:57:28 How do I find the correct fuse to replace with? I know what the rating is, but not the Breaking Capacity Current AC. I assume this is somewhat important. (Apologies, I'm not an electronics expert by any means). Example:   A Time Delay 2A 250V fuse from a Mac Classic analog board, what would the Breaking Capacity Current AC be? I have choices of 2A, 35A, 100A, 150A or 1.5 kA. I thought it would be marked on the board but I cannot see it. Same question goes for fuses found in LC PSUs and SE PSUs.

Posted by: jessenator on 2020-04-12 09:05:39 2A 250V My Mac Classic parts analog board says at fuse FP1: T 2.5 A 250 V

Posted by: joshc on 2020-04-12 09:07:31 My Mac Classic parts analog board says at fuse FP1: Yup, I got that far. So my understanding is that 2A is the fuse current, but what about the Breaking Capacity Current AC? Product listing that matches 2A 250V: https://uk.farnell.com/w/c/circuit-protection/fuses-fuse-accessories/fuses/cartridge-fuses?blow-characteristic=time-delay&fuse-current=2a&voltage-rating-vac=250v&fuse-size-metric=5mm-x-20mm

Posted by: joshc on 2020-04-12 09:09:48 2A was just an example - that's actually the fuse in a TDK LC PSU, but I think my question is still relevant 🙂 My Classic II board uses a 15A/250V fuse.

Posted by: jessenator on 2020-04-12 09:12:09 Interesting. Mine is 2.5 A In my conversations with electrical engineers, I've gathered that breaking capacity in consumer products like this is not that much of a deal breaker.  I'd be fine even buying something as simple as these: https://www.acehardware.com/departments/lighting-and-electrical/circuit-breakers-fuses-and-panels/fuses/3492105 But that's just my experience 🙂

Posted by: IlikeTech on 2020-05-26 04:57:29 I just looked it up, and breaking current appears to be the current that you can run through the fuse without it physically exploding.  It should be higher than the fuse's current rating to pop.

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