Synergistic Red Fuse ...

Okay guys, I need some help in understanding what SR Black fuses to order this round. First, an admission and then a question.

The admission: I posted earlier in this thread that I had two SR 1A small Black FAST fuses blow in my Ayre K-1xe’s external power supply when plugging in the power cord. After re-inspecting the stock fuse I realized that the marking nomenclature had a "T" at the beginning, as in "T1L250V". Not knowing what that meant initially, I simply looked at the filament and saw that it was thin with no windings around it (like the higher value SLO BLO fuses I had around) and ASSUMED that the original fuse was FAST blow. After doing some research, I learned that the "T" means "Timed" and therefore SLO BLO. That probably explains my problems with the FAST BLO fusing blowing. A pretty expensive mistake. Doh!

The question. I am ready to order SR Black fuses for my REL subs. The "power fuse" is a small GLASS fuse that has this marking: "T5AL250", so I should order the SR SLO BLO 5 amp fuse.
Now for the twister: The RELs each have two SMALL rail fuses on the circuit board inside the cabinet that have WHITE BODIES (CERAMIC?) with markings "T6.3 AH 250V". Research online gives mixed opinions as to the advisability of replacing a ceramic fuse with a glass one. Bottom line: is it okay to use SR Black fuses of the same rating to replace the stock CERAMIC ones in the RELs?

Best to you all,
Dave

Hi Dave,

I believe that the main difference between a ceramic fuse and a comparable glass fuse is usually in what is called "breaking capacity." That refers to the maximum amount of current the fuse is rated to be able to safely interrupt when a fault requires it to blow, that would not result in it rupturing or exploding or failing to open the circuit. And I believe that ceramic fuses tend to have much higher breaking capacities than glass fuses that are otherwise similar.

So that difference would only come into play if a fault arises in the sub which requires the fuse to blow. But whether or not the breaking capacity of the SR glass fuse would be adequate in that event can't be predicted with any kind of certainty without knowing the details of the sub's circuit design, and without having detailed specifications on the SR fuse. FWIW, though, my guess, based just on instinct, is that it is unlikely that you would ever have a problem as a result of that difference.

A separate question, though, is whether it would be advisable to choose an SR fuse having a somewhat higher current rating than the stock fuse, to minimize the likelihood of the false blows that various people have reported in this thread. My guess, again based just on instinct, is that it would probably be a good idea to go up one rating increment, which if I recall correctly would be to 8 amps.

Good luck. Best regards,
-- Al

Thanks Al. I was speculating that REL used the ceramic fuses to buffer against extreme vibration as might be encountered inside a sub enclosure.

I am beginning to believe that upping the fuse rating to the next increment is indeed a good idea with all of the SR Black fuses for toroidal power supplies.

Thanks again Al and Merry Christmas,
Dave

You're welcome, Dave.  BTW, I'm not sure if the reference in the second paragraph of my previous post to the SR fuse being glass was correct.  But in any event the rest of my post remains as stated.

Best regards,
-- Al
 

Oregonpapa

Good day to you, my friend.

Earlier this morning I was cleaning out an area under my staircase when I found an unopened package marked "QUAD". It is a brand new Treble panel (complete with dust cover) for the the Quad 57 electrostatic loudspeaker. .

This part might be unavailable. I would hate to throw it in the garbage. I am sure there is somebody out there who would love to have this.

I am not selling it but would gladly donate it someone who needs it.