SEX 2.1 started blowing fuses. Help! [solved]

[ggoodale]

Yes, yet another blown fuse thread.  I should buy stock in Bussman. 

I've been using this amp at my office for several weeks without issue.  Brought it home to test it out with a pair of high-efficiency speakers, and blew a fuse powering it on (no speakers or headphones connected at the time). Guessing I jostled something marginal in transit.

Ran through the steps outlined in other threads - Impedances are within spec everywhere (0.3-0.5Ω on the 0Ω taps if it matters, but it was suggested that it doesn't in another thread so I'm discounting it for now).  With the tubes removed, everything's fine; with the tubes in, fuse blows instantly. Using 1A250V fast blow fuses if it matters. 

Looking for next steps to test - I've got 4 more fuses. Save me a trip to the store!

[Jim R.]

How about a trip to the store... and pick up some slow blows.

Sorry, but that could be the problem, but also go through and check for anything m amiss physically andredo the resistance and voltage checks.

Sorry if you said that in the paragraph above, but it seemed to talk to me in Japanese.

HTH,

Jim

[ggoodale]

Slow-blow fuses are definitely a possibility, but I'm hard-pressed to explain why fast-blow worked great before I brought the amp home but not after. My gut is that something got bumped in transit and is now shorting; hoping someone has suggestions on where to look. Can't do the voltage checks until I stop blowing fuses.

[Paul Birkeland]

If the amp will power on with no tubes in, then try with one tube.  (Well, try each tube on its own)

[Jim R.]

Goodale,

Sorry, I changed the multi-language support and was able to read the paragraph where you said you did some resistance checks. (I'm blind and my computer reads n-screen text to ,e)

PB is right - power it on with only one tube at a time., and then try both tubes with a slow blow fuse (the slow blow fuse is what is supposed to be in the kit), and if there's no joy there, redo all the resistance and voltage checks, probably concentrating on the power supply terminal behind the power transformer.

One possibility why the amp worked at your office and not at your home may have to do with linve voltage differences -- you don't happen to know what those are, do you"

Good luck,

Jim

[ggoodale]

Thanks for the help everyone! Turns out I should try things before discounting them - a slow-blow fuse did indeed solve the problem.

[Jim R.]

The s.e.x. kits are supposed to ship with slow blow fuses, fut every once in a while some fast blows gget themselves in the mix No worries, you wouldn't be the first to encounter this.

Glad it's all working now.

-- Jim