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Posted by: Xuestor Sep 9 2008, 08:25 PM

Hey!

I have a Switchblade tubeamp, and I think a fuse has blown. Today the sound just died. The tubes still glow, and cables are already checked. It's a bit messy in the manual, so if someone know which fuse it is that has blown, this would be very helpful. Is it the Anode fuse?

Can I change fuses by myself, or is it much hassle?

/Xuestor

Posted by: Ivan Milenkovic Sep 9 2008, 08:51 PM

Probably Andrew can help you with that, but nevertheless if you're not that experienced maybe it is best to get head to amp tech. That's what I would do, but if you're a DIY type, try it out if it is fairly easy.

Posted by: MickeM Sep 9 2008, 09:20 PM

It sits right under the 230V power cord socket in the back. I suggest you get a couple fuses and if it blows again right after you replace it it's likely you have a powertube that went out causing this problem.

Is there a strange glow in one of them or any grey/white film inside or is the written letters on the tubes burnt?

EDIT: I should say main fuse sits there. There are other fuses aswell but sorry, I don't know where
I'll have a look see if I can find anything.


EDIT2: There's one below the power-input and one right above it.

Posted by: Bogdan Radovic Sep 9 2008, 09:39 PM

Hmm I don't think its the main fuse (next to power cord input)...because there would be no power entering amp, tubes wouldn't glow ...Hmmm check with guitar and everything and also tubes them self....I'm pretty sure if its not the main fuse blown , you will have to take the amp to tech to figure it out and fix..

Posted by: MickeM Sep 9 2008, 09:55 PM

Yeah that's right. It would be the anode fuse then since the tubes are still glowing. I had a blown fuse in my brain in my first post about fuses.

There could be a number of problems like the transformer, the head connected to the wrong impedance cabinet, or a powertube that's run out (change all four in that case)

If it was me I'd change the anode fuse first myself. If it blows again I'd try another + changing all the EL34's. If it blows again, it's a work for a technician.
First of all though, check that you're connected to the correct inpedance. It's always a good idea to measure the cabinet, stick a speaker cord in and measure with a volt meter. One connection on the tip and one on the sleeve. Should be close.
I have a Marshall cab that's close to perfect and then I have a noname cab that's way off, between 8 and 16 somewhere (11 if I remember well) where it should be 8.


But if you feel unsure then go to a technician straight away and they'll fix it.

Posted by: Xuestor Sep 10 2008, 09:17 AM

Yeah, I am pretty sure it's the anode fuse aswell, since the tubes glow, and leds on the front still works as they should. I checked the manual, and it doesn't say what type of anode fuse there should be. It only specifies the main fuse. Is there only one type of anode fuse like this?


EDIT: Is there high voltage involved also when only changing fuses? I've had the head unplugged overnight now though...

Posted by: MickeM Sep 10 2008, 11:36 AM

That's where the hi voltage is. From what I've learned you drain an amp by turning it on, letting it warm up and then pull the plug out of the wall socket. Drains it quickly. If you power off it could contain enough for a shocker for days and weeks. Still, even if you think it's drained be very careful. But now for this it's not like you're opening it up.

Anyway, the fuse sits in a plastic socket that you turn and pull out. You better do that and check the size (length and diameter)
My guess is that's it's one of these (can't check my own amp since it's in the rehearsal room far away) www.elfa.se and key in product 33-105-39
Try to read off of it what it says. Or better yet, send a mail to H&K support, they are quite fast on replying. At least theye were to me when I had a broken MIDI pedal.

Posted by: Xuestor Sep 10 2008, 05:31 PM

thanks for the reply!! I just thought about something, I would really like to see a video demonstration or tutorial on how to change tubes here on GMC. I know there are a tutorial on expertvillage, but that one seems very short and too speedy.

Posted by: kjutte Sep 11 2008, 03:31 PM

If a fuse has blown, the amp won't work.
Take it out and check if it's still coupled. There will be a wirebreak in the fuse if it's broken.
They are easily changed.