AC30 power issue

Voodoomailman · 18th January 2012

Hi, I posted a couple weeks ago about a '97 Vox AC30/6 TBX. The main fuse blew so I changed the rectifier tube and that seemed to fix the problem. But today the fuse blew again. I changed it and now I can turn the main power on... but the moment I take it off standby it makes a horrible rattling noise like it's trying to power up but can't. It won't blow the main fuse as long as leave standby on.

Do I need to try putting in new power tubes? Or could my new GZ34 have died already? Could the pre amp tubes have anything to do with this? Is it ok to take the GZ34 out and try and power the amp up to see if that's the problem? If possible, I'd love to figure out what the problem is before spending any more money.

Thank you!!!

Voodoomailman · 18th January 2012

oh yea... and the internal fuses seem to be fine.

nedorama · 18th January 2012

I believe it was pointed out in your last thread - take the amp to a competent amp tech to have them look at it. Fuses blowing are a symptom, not the problem. My concern is that if you don't know enough to fix it (neither do I), chances are you could damage it further. That's why I've found a good amp tech near me in LA that works on all my amps. I'll change a preamp tube but that's about it.

If you post where you are located, people can give suggestions on amp techs to take it to.

jpindustrie · 18th January 2012

How old are the valves in the amp? Are we talking the stock chinese set from 1997, or have you changed them in the past? Did you buy the amp used?

The tech may charge an hr's worth of work just to tell you to buy his overpriced tubes he has for sale and a bad power tube could cause fuses to blow. Couldn't hurt to have an extra set of tubes especially for something like your older Vox reissue.

The mid-90s MIUKbyMarshall Voxes are very close to the original design albeit with some cheaper/cost effective changes; if you are so inclined this AC30 is one of most well known designs on the planet. O, and you will absolutely need the GZ34 recto tube in there or you will most certainly damage the amp

nedorama · 19th January 2012

Quote:

Originally Posted by jpindustrie

The tech may charge an hr's worth of work just to tell you to buy his overpriced tubes he has for sale and a bad power tube could cause fuses to blow. Couldn't hurt to have an extra set of tubes especially for something like your older Vox reissue.

Which is why I recommended he post his location, so that fellow members can recommend techs that don't pull that crap.

From the OP's posts, he needs to stop turning the amp on and get it to a tech - his amp is way better than the current CC models and would hate to see further damage happen.

Voodoomailman · 22nd January 2012

Well... my problem is that I'm in Wellfleet, Cape Cod, MA.... and I don't have a car! I'm holed up here for the Winter writing music... so there's really no way for me to take my amp anywhere for another two months. I am very hesitant when it comes to trying to fix my amp on my own... but I really don't have a choice.

nedorama · 23rd January 2012

Understand the dilemma; my concern is that if you are hesitant, trying to fix it may result in your amp getting even more damaged. If you can live without it for 2 months, I'd do that. Not optimal, but unless you're super comfortable working on your amp I wouldn't.

Voodoomailman · 25th January 2012

Do you think it might be worth it to try changing the power tubes? I just got some new ones shipped to me...

18th January 2012	#1
Voodoomailman Gear interested Joined: Jan 2012 Posts: 9 Thread Starter	AC30 power issue Hi, I posted a couple weeks ago about a '97 Vox AC30/6 TBX. The main fuse blew so I changed the rectifier tube and that seemed to fix the problem. But today the fuse blew again. I changed it and now I can turn the main power on... but the moment I take it off standby it makes a horrible rattling noise like it's trying to power up but can't. It won't blow the main fuse as long as leave standby on. Do I need to try putting in new power tubes? Or could my new GZ34 have died already? Could the pre amp tubes have anything to do with this? Is it ok to take the GZ34 out and try and power the amp up to see if that's the problem? If possible, I'd love to figure out what the problem is before spending any more money. Thank you!!!

18th January 2012	#3
nedorama Lives for gear Joined: Jan 2008 Posts: 1,242	I believe it was pointed out in your last thread - take the amp to a competent amp tech to have them look at it. Fuses blowing are a symptom, not the problem. My concern is that if you don't know enough to fix it (neither do I), chances are you could damage it further. That's why I've found a good amp tech near me in LA that works on all my amps. I'll change a preamp tube but that's about it. If you post where you are located, people can give suggestions on amp techs to take it to. __________________ nedorama Monkey Boy Studios Summit 2BA-221, TLA-50 mBox Pro 3, Pro Tools 10.1.3 Radial JDI x 2, ProD2, ProRMP '65 Bandmaster 2x12 combo with Dr. Z Brake Lite, '65 Showman, '74 Princeton, '77 Princeton Reverb, Dr. Z. Mini Z Head, Dr. Z 1x12 Cab, pedals, George L's cabling

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18th January 2012	#4
jpindustrie Gear interested Joined: Jan 2012 Posts: 3	How old are the valves in the amp? Are we talking the stock chinese set from 1997, or have you changed them in the past? Did you buy the amp used? The tech may charge an hr's worth of work just to tell you to buy his overpriced tubes he has for sale and a bad power tube could cause fuses to blow. Couldn't hurt to have an extra set of tubes especially for something like your older Vox reissue. The mid-90s MIUKbyMarshall Voxes are very close to the original design albeit with some cheaper/cost effective changes; if you are so inclined this AC30 is one of most well known designs on the planet. O, and you will absolutely need the GZ34 recto tube in there or you will most certainly damage the amp

22nd January 2012	#6
Voodoomailman Gear interested Joined: Jan 2012 Posts: 9 Thread Starter	Well... my problem is that I'm in Wellfleet, Cape Cod, MA.... and I don't have a car! I'm holed up here for the Winter writing music... so there's really no way for me to take my amp anywhere for another two months. I am very hesitant when it comes to trying to fix my amp on my own... but I really don't have a choice.

23rd January 2012	#7
nedorama Lives for gear Joined: Jan 2008 Posts: 1,242	Understand the dilemma; my concern is that if you are hesitant, trying to fix it may result in your amp getting even more damaged. If you can live without it for 2 months, I'd do that. Not optimal, but unless you're super comfortable working on your amp I wouldn't.

25th January 2012	#8
Voodoomailman Gear interested Joined: Jan 2012 Posts: 9 Thread Starter	Do you think it might be worth it to try changing the power tubes? I just got some new ones shipped to me...