SWR 550X- Powers up...no sound?

[Southpaw5]

So I've had my 550X for about 6-8 months, bought used. It's been nothing short of reliable until right now. On wednesday night I arrived at practice turned on my amp, let it warm up, and tried to play out. I heard 2-3 distorted notes fizzle out and...dead. I checked my speaker cables(and made sure no one "borrowed" mine and replaced them with instrument cables) and made sure my fuses were still attached, they are but I don't know how to tell if they're blown(advice please!) One is clear with a visible filiment, the other is solid white so I can't see anything inside it. However, the DI out works to send to our PA. Obviously I can't do that for a show, which I might add, will be on Saturday. I may be able to borrow my guitarists B-25b to use as a monitor since They'll DI me at the gig, but I'd really rather use mine since I won't have any need to run DI and have the house decide how I should sound( that never ceases to make me PO'd)

Any Ideas whats up and If this is something I can fix myself?

Amp Gurus, I Desperately need your help!

[Southpaw5]

Could it also be that the 12ax7 is kaput?

Thanks

[RickenBoogie]

The ONLY way to know for sure, is to take it in to a qualified amp technician.

[BassmanPaul]

Originally Posted by RickenBoogie

The ONLY way to know for sure, is to take it in to a qualified amp technician.

Yep! It's tech time - sorry.

[Southpaw5]

Thank Guys, I did get an extended warranty on it when I bought it so it will be going to a tech eventually, once they get back to me which should be tomorrow. I was really just hoping there was a chance of this being something I could fix myself before my gig tomorrow.

Oh well, guess thats life. My luck with amps is no good right now. The VB-2 I received on Friday had been completely pulverized by UPS and I won't be getting a replacement for at least a month.

[dincz]

A quick and easy check - plug a cable from fx send to fx return. You MIGHT just have dirty contacts on an FX jack.

[Southpaw5]

So I was told that my drummer was jamming with some friends and it looks like they had a third cab hooked up to my amp ,which can only handle down to a 4ohm load. All three cabs are 8 ohm, so that would be a 2.67 ohm load right?

Anyway my guitarist who knows a bit about amps rechecked the fuses and one had a broken filament, it was very fine and hard to see and swapped it out for an extra he had. Amp played fine throughout practice.

Now, given the ohm mismatch, does it sound safe to think that the cause was just the extra cab?

[Bufalo]

Yup, if the amp isn't stable below 4ohm, and the speaker fuse was blown - there's your culprit and your solution.