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  #1  
Old 12.27.06, 9:18 AM
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Exclamation HELP! Urgent Vox AC30 help needed

Sorry for the forceful title but I really am going mental right now.

At band practice today my VOX AC30 CCH's main fuse just kept blowing, three times to be exact. All the other guys amps ran fine. The Vox AC30 has two fuses, the amp fuse is fine, just the mains keeps blowing, it goes on for like 5 seconds them thems and I pull out a smoked fuse.

I visited the offical Vox page and it seemed to say that I may need to change my rectifier valve (my amps still new). Will that fix it?

I am in urgent need of assitance since we have a gig on the 6th of January. I can borrow an amp, maybe, but I really want to get my Vox running as soon as.

ps I sent Vox an e-mail too, but it keeps saying "message cannot be delivered as the box is full". WTF?

Anyway any advise much appriciated.
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  #2  
Old 12.27.06, 7:27 PM
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Take it to the place you bought it from or if you got it online take it to your closest local Vox dealer. At the very least they can probably put you in contact with Vox. Sorry I can't be of more help but I'm not real techsavvy.
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Old 12.27.06, 8:35 PM
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i have an english made ac30...that same thing with the fuses happend to me, i took it to my tech and it was the rectofier valve....but the amp had not been revalved in 4 years so i got the hole thing done....its now sounding better than ever ...so yeh its probly the recto...get it checked out..

as for it happening so soon after you bought it.....remember its made in china..
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Old 12.27.06, 8:52 PM
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it's either the rectifier or possibly the power tubes. when this happened with my CC i just changed both, so now i have spares in case it happens again
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Old 12.27.06, 10:27 PM
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Okay here's another quick question. According to the Vox site I if the fuse keeps blowing, its the rec tubes.

If I track down exactly the right fuse for this amp, and test it at home it might save me taking it in (a serious pain as I dont have a car, its New Years holidays and my Japanese is medicore at best). However I dont keep cabs at home. I am well aware that you should turn on tube amp without a speaker load but what if I keep it on stand-by and just test the mains fuse?
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  #6  
Old 12.28.06, 2:50 AM
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I'm not really sure what you are asking here. Why test the mains fuse if you haven't replaced the recto tube? You'll just waste another fuse
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  #7  
Old 12.28.06, 5:57 AM
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Quote:
Originally posted by ames ace
I'm not really sure what you are asking here. Why test the mains fuse if you haven't replaced the recto tube? You'll just waste another fuse
What I mean is I change replace the recto tube and fuse by myself. I may just want to make sure it works at home before I waste money and energy taking it to a studio to test. Even on standy if the red light stays on, thats a good sign.

I've read that Class A\B amps can be turned on without a load as long as you leave them on standby (I only want to check the mains fuse and power).

I think AC30s are Class A\Bs and it may be okay. Yes? No?
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Old 12.28.06, 6:30 AM
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Ah, ok, now I'm with you. As far as I know, the problems with switching on an amp without a load is that it overheats the output transformers, so I would have thought if you just quickly switched it on to test the fuse then off again it would be ok, but I wouldn't at all advice you to do it just because I say so, I'm not an expert on tube amps at all.
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Old 12.28.06, 8:00 AM
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the thing about a no-load condition that kills an amp is that the output transformer reflects the very high impedance to the power tubes, resulting in potentially thousands of volts on them. this can fry the tubes or the transformer. if there is no signal being applied, it's very unlikely that there will be sufficient reflected voltage to hurt anything. don't plug in your guitar and keep the master volume all the way down and you should be fine for a second or two.
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Old 12.29.06, 2:04 AM
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Okay the fuses aren't a problem but none of the guitar store in Tokyo stock the GZ34 tube. I'll have to order it but all the warehouse are on holiday until the 5th and my gigs on the 6th.

One shop guy told me that old style "ham radio" stores sell them (GZ34s exactly) and maybe I could use that. They are cheap and not made by any guitar tube brand (not Sovtech or JJs for example). A GZ34 is a GZ34 right? Just a recto tube? If I get any old GZ34 will it work? Sound crap?

Thanks.
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  #11  
Old 12.29.06, 4:55 AM
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Hello

Try Ishibashi Music store in Yokohama
It is located out of the west exit of the Main Yokohama station in the area where HMW, the movie theatre and all are. Its on the very top floor of the Dai-ei there.

Last time I was there they had a wide selection of tubes, so you might want to try there.f

Hey PM me, I know we talked briefly before, but lets get contact info, I am looking for other musicians in the Tokyo, Yokohama area
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  #12  
Old 12.29.06, 8:44 AM
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Quote:
Originally posted by bassvi
Hello

Try Ishibashi Music store in Yokohama
It is located out of the west exit of the Main Yokohama station in the area where HMW, the movie theatre and all are. Its on the very top floor of the Dai-ei there.

Last time I was there they had a wide selection of tubes, so you might want to try there.f

Hey PM me, I know we talked briefly before, but lets get contact info, I am looking for other musicians in the Tokyo, Yokohama area
Thanks, thats actually exactly where I went today and they didn't have it (though they can order it). They also rang around the other Ishibashis around Tokyo area and they dont have them either.

They said (and I think they're right) that the GZ34 is a rare tube for guitar amps since most these days are solid state recto not tube. They did however have a wide selection of 12AX7s and EL84s which may be useful later.

Shimamura music is another good store (top of Vivire in Yokohama) where I bought it but they don't stock tubes at all, but again can order. They problem is most of Japan is now on New Years break so I cant get it as urgently as I need.

Don't get me wrong, the service in Japanese guitar shops is outstanding (and if they don't know something they don't pretend they do). Way better than back home. If you are a regular they will hook you up all sorts of sweet deals (how I got my AC30 so cheap).

Akihabara has every electric gizzmo under the sun and I was told for sure by the Ishibashi staff that "Radio shack" in Akihabara stocks GZ34 tubes for old school audio equipment. Seems my best bet.

off topic, what do you think you Ishibashi 2nd hand system? I've gotten some great stuff there cheap espeically my old model RAT2.
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  #13  
Old 12.30.06, 6:01 AM
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Okay I managed to track down a Sovtech GZ34 (surprisingly easy in Tokyo "electric town") but I really having trouble finding the right fuse.

It's a T4AL 250v "time lag" fuse. Honestly NOBODY stocks it. Not guitar shops, not electric shops, nobody.

How important is the time lag fuse? Could I try, say, a slow blow 250v 4 or 5 amp fuse instead?

A lesson to all AC30 owners I guess. EL84s and 12AX7s are very common but the fuses and GZ34 are rare so its smart to have spares. I guess I wasnt so smart....

Edit: I just tested it and it seems fine. Ill take it too the studio and crank it to make sure. I just found out that a 4amp "slow blow fuse IS a T4AL (4a for 4 amps, TL for "time lag") for anyone else who needs them. Most people didn't know what it was but it was just the weird name.

Thanks for the help everyone. I would be stuck without my fellow geeks....
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Last edited by jayjay; 12.30.06 at 7:50 AM.
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