Started 4 years ago by artkau
Topic Rating:
Hi all. My 6 month old precious lady is blowing fuses suddenly, I understand this may be a tired Rectifier Tube? GZ34? Please correct me? Advise me? Is it easy to do? I can't manage to get access to the tubes, and don't want to remove too many screws. Thanks guys!
Posted 4 years ago
my ac30cc is doing this too. it's done it twice in the last 3 months, and this time replacing the fuse has not fixed the problem. so i have a useless amp right now. obviously something is causing this to happen, and its really irritating.
Posted 4 years ago
Hi Guys
Sounds like your GZ34 (5AR4) rectifier tubes has gone faulty.. The HT fuse has blown to protect the circuitry inside from being damaged.
artkau... it is very simple to get access to the tubes:
1. remove the 2 screws at the bottom of the rear chassis cover (one to the left and one to the right)
2. Remove 4 screws used to home the amp tray in place... for this you'll need to reach into the speaker cabinet, there are 2 near the front (near speakers) and 2 near the back.
once you've done this, simply slide the amplifier chassis out and you will have access to the tubes. The GZ34 is the large tube nearest the power transformer..
Hope this helps
Thanks
Dave
Posted 4 years ago
Hi Dave
I too face this problem on my ac15 n ac30 they only less than 6 mths
Can you tell me ,what cause the problem.
thanks
Michael
Posted 4 years ago
I don't have an AC30, but I'm hearing alot about standby switch problems where there is a 700 volt surge hitting the rectifier tube, causing them to burn out. If it's true, this is insane, and Vox needs to fix this pronto. Don't touch anything inside the chassis unless you know what you're doing. There's high voltage stored in the filter caps waiting to knock you across the room, so be carefull. I have the AC15CC1, which has a solid state rectifier, and I've had no problems.........barryg
Posted 4 years ago
Hello guys,
I have some trouble with my AC30CC2, hopefully you can help me,
One year ago a switched ON the amp as usual and after 4 or so minutes the mains fuse (not the HT) blew and the amp lost his power, so i tried changing fuses and kept blowing them, after 3 blowen fuses i decided to change the gz34 and had no problem for 4-6 months, then the same again but this time i believe i switched the standby too soon. anyway, after changing the gz34 4 times this year i believe i need some help to find what the problem might be.
Anyone know what the problem could be? I don't really know if the gz34 are blowing or not,
How do i know if the problem is the power transformer or the other valves?
Thanks for your help
Posted 3 years ago
And what's that about not using the standby switch? would it help not to use it? sometimes when i switch the standby the amp makes a crazy noise on the top left side and you can even feel some little vibration.
Posted 3 years ago
I don´t know if it was here or on the Vintage forum this was discussed but I think the point was that the GZ gets stressed when you turn the stand by on so better to always have the stnad by on and jjust turn the power on and off. I´ve done this since someone told me this and I also read this
Posted 3 years ago
Thanks pemich. Now the only thing is to fix this amp for good (or for as long as possible) should I try the amps without the gz34? see if it runs?
How do I know if its the valves that are tired? or if its a bigger issue?
Also, on the troubleshoot it says that the problem might be the mains switch or the transformer...but as i know little about this i don't really know where the problem is!
Posted 3 years ago
There are probably guys here that knows about this much better than I do:-)) I would let an amptech have a look at it as there might be some other things inside. I use actually a SS rectifier from Groove tubes in one of my TBXs. They last forever
Posted 3 years ago
Great, thanks again.
So i checked the amp without the rectifier and everithing seems to be running just fine, i didn't switch on the standby though.
i though the two thun-sol 12ax7 where broken because they didn't light up, but apparently they don't when they're working properly... so it might just be the rectifier, i'll try the ss from Groove, but what about those JJ??
also, how do i know if there's a problem with any of the transformers (OT, choke or PT)
Posted 3 years ago
And the biggest question, should I continue using my standby switch? to be honest i feel like its giving me only trouble, everytime i switch it i get the feel i break my amp a little bit more. I went to san francisco one month ago and walked in a guitar center and the guy who was showing me one guitar plugged it on a ac30 and switched the mains switch and the standby almost at the same time (i mean less than 5 seconds after).
Posted 3 years ago
I have a AC30H2 and AC15H1 Heritage. Vox left the standby switch out of these models. But I have blown the rectifier tubes when I tuned the amp off and right back on. Blew both fuses and the rectifier tube. So now if I turn off the amp I wait a minute before I turn it back on. Other than that I have had no problems turning on and off the amp without the stndby switch.
Posted 3 years ago
i started using the standby switch allways on and it didnt help me, just blew my first fuse, the amp is only 2 months old.. had all tubes changed to ruby tubes (JJ´s inside) and a groove tubes rectifier 2 weeks after buying it... so you know i have the bright cap mod done.
Posted 3 years ago
...but i dont really think that messing with the bright cap would not cause such nasty effects. May be just an unfortunate design flaw.
Posted 1 year ago
