0
\$\begingroup\$

I'm trying to replace a blown fuse from my stereo system. The fuse has the following markings on one end: 125V 5A and the following on the other: 51MS, an H with a circle around it (I'm assuming this means Hitachi), and some other symbols including the Underwriter Lab logo, an "SA" logo and an inverted triangle with a "T" inside (drawing below) and a line just above the T. It's 5mm x 20mm

T Marking

The fuse has a wire, then a small blob of metal, then another wire (which, to my untrained eye seems a bit thicker).

I think this is an M Spot Fuse, as described by @Harry Weston in this answer: Slow Blow vs Fast Acting Fuse

As far as I can tell, this is a Hitachi FN00373. Unfortunately this is a really rare fuse. I should also mention this stereo system is about 10-15 years old.

Is it possible/advisable to use a different fuse in its place (I'm not sure I can even get the Hitachi fuse anymore). Or, is it possible/advisable to use a slightly different fuse (e.g. one that isn't "M Spot" or has a slightly different voltage/current rating)? If you can recommend one, that would be ideal!

\$\endgroup\$
  • 1
    \$\begingroup\$ What size is it? Common North American fuses are 1/4" dia 1 1/4" long, while metric fuses are 5 x 20 mm (or so). \$\endgroup\$ – Peter Bennett Oct 13 '16 at 20:13
  • \$\begingroup\$ Thanks for asking. It's 5x20mm, I just updated the question as well. \$\endgroup\$ – SimaPro Oct 13 '16 at 20:15
  • 1
    \$\begingroup\$ There's one question you haven't thought to ask, which could make the whole concept of replacing the fuse null and void: why did the fuse blow in the first place? \$\endgroup\$ – Majenko Oct 13 '16 at 21:16
  • \$\begingroup\$ That's an excellent question, however I haven't touched this system in over half a decade. If I recall, I had been messing around using the system on different speakers, or with splicing the wires to make them longer. I think that's when it started. Anyway I just picked it up recently trying to figure out if I could fix it. \$\endgroup\$ – SimaPro Oct 13 '16 at 21:19
4
\$\begingroup\$

Turns out that "51MS" is an entire family of fuses, all with the same basic characteristics but different current and voltage ratings. Assuming you can't find another "51MS-050L" from another manufacturer to replace it, you should be able to get away with any leadless, 5.2mm×20mm, medium slow-blow fuse rated for 5A and at least 125V.

Source 1

Source 2

Source 3

\$\endgroup\$
  • \$\begingroup\$ Thanks Ignacio. Can you comment on the form factor? Having that wire->metal blob->wire format? Can I do with a fuse that doesn't have that? Also if you can share any links off hand that would be a huge help \$\endgroup\$ – SimaPro Oct 13 '16 at 21:26
  • \$\begingroup\$ I'd have to see a picture of that to understand what you mean. \$\endgroup\$ – Ignacio Vazquez-Abrams Oct 13 '16 at 21:27
  • \$\begingroup\$ There's a picture in the first question of the other answer I linked to. \$\endgroup\$ – SimaPro Oct 13 '16 at 21:28
  • \$\begingroup\$ The other answer called it an MSpot fuse \$\endgroup\$ – SimaPro Oct 13 '16 at 21:28
  • 1
    \$\begingroup\$ The first link shows the internal Hitachi part number, and the third shows that it's a standard family. \$\endgroup\$ – Ignacio Vazquez-Abrams Oct 13 '16 at 21:41
0
\$\begingroup\$

125V 5A quick blow (51MS) Radio Shack

125V 5A 51 millisecond, available at Radio Shack, some auto stores, walmart etc. Was this soldered in, or is it just a glass fuse? Also, take a meter to it and verify that it is blown. It may be something internal.

\$\endgroup\$
  • 1
    \$\begingroup\$ I'm not convinced the ms stands for millisecond, because then I would have expected "ms" not "MS". Also I think there's some subtlety here with fast vs slow and the form factor (m spot vs f type) \$\endgroup\$ – SimaPro Oct 13 '16 at 21:24

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.