Synergistic Red Fuse ...

I have found that the Synergistic fuses to be quite touchy and will blow quicker than many other fuses of the same value. I was told that they are held to a more exact value than others. In fact AA advised me to get a slightly larger value when using Synergistic fuses.

To further clarify Synergistic Research Dealer:
Alfred Kainz," highend- electronics.com". Apple Valley, California.
Look under tweeks on the Audiogon for" sale page".

Jon, sorry that you’ve experienced this issue. I have no particular suggestions beyond what Sgordon1 has said (although you indicated that you’ve already performed step 1 of his suggestions), but the following may have some relevance:

I took a look at the detailed technical info for the 0.25A 250V 5x20mm fast blow fuses manufactured by Littelfuse, one of the leading makers of non-audiophile fuses. Interestingly, they offer at least four different series of fuses of that specific type, designed to various combinations of UL, IEC, and other standards, which have "nominal melting points" (defining the combination of current and time that will cause the fuse to blow) ranging from 0.0166 amps squared-seconds to 0.042 amps squared-seconds. That’s a difference of a factor of 2.5, even though all of those fuses are from a single manufacturer and all are 5x20mm fast blow fuses rated at 0.25A 250V.

If the stock 0.25A 250V 5x20mm fast blow fuses in your amp are rated at or near the upper end of that 0.0166 to 0.042 range, and the unspecified rating of the SR fuse is at or near (or even below) the lower end of that range, it would certainly seem to account for what happened. If you call SR, you might ask them if they can tell you what the nominal melting point of that fuse is, in amps squared-seconds.

Good luck. Regards,
-- Al

One would hope Synergistic will do something to help out in a case like this.    It is an expensive experiment for someone and not user fault if apparent correct fuse blows unexpectedly.  One the right fuse is found, should not be a common occurrence anymore I would hope.