Vox AC30CC troubleshooting

[Gretch]

Hello Good People,
I have an Vox AC30CC2X, I bought it used a year ago, very satisfied customer until last night. I turn the switch on (red light was on) and went back to the kitchen to make myself a sandwich while the amp was warming up. Sandwich was delicious, my trick is to use... nevermind, when I was done eating, went back to play but my amp was not working! No red light, it basically looked like no power was going to the amp.

I haven't investigated much so far, except for plugging it in a different power outlet, still not working. I like to try to fix stuff by myself if possible before taking it to a tech. Any ideas? I will obviously check the fuse but any other suggestion will be appreciated!

Thanks for your help. Wish my first post was about a more exciting subject!

Gretch

[54GT]

Check the rectifier tube. Some AC30CCs have issues with blowing these.

[utterhack]

You have 99% likely lost the rectifier tube and probably the fuse that's in the pullout tray where you attach the mains plug. Check the one next to it as well.

Roll up your sleeves, because getting to the chassis is a drag. Replace the rectifier and fuse(s) with known good ones, then turn the standby switch to ON and never touch it again. The amp will be fine and will thank you for it.

A little more detail on this if you're curious:

Do Not Use Standby on an AC30: http://vintageamps.com/plexiboard/vi...hp?f=2&t=75667
Vox AC30s: to use standby switch or not: http://www.vintageamps.com/plexiboar...80999&p=799182
The Old Standby Switch Chestnut!: http://vintageamps.com/plexiboard/vi...hp?f=2&t=81689

[sixstring531]

Rectifier tube and the little fuse underneath your ac cable. change both and tell me how you feel in the morning.

[Gretch]

Thanks a lot for this great input. I am (was) indeed "standby switch power user", being fully convinced that this was the best way to extend the life of the tubes in my amp, I'll stop using it I guess.

I'll have a look at the fuse and the rectifier tube. One quick question, what does a blown tube looks like compare to a functioning one? This is my first tube amp...

[utterhack]

Congratulations on your first tube amp! The good news is, no other tube amp you ever own will be as much of a pita when it comes to tube changes.

The bad tube won't look any different. But if you pull the chassis, plug it in, and turn both switches on, you may get a lightshow!

btw, in most amps the standby switch is a fine idea... just not this one.

[sixstring531]

blown fuse will either look normal with the little wire in the middle melted in half or, as in every blown tube I've experienced, look black and smokey with the wire in half.

Yeah, that amp is not so friendly when it comes to changing tubes. They aren't hard to get to, just a bunch of screws that melt like butter when you try and touch them with your tools. They are soft, so be careful.

[mobis8]

It is odd that the amp stopped working after you turned it on and walked away. You have heard from others that the standby switch is not a good idea on this amp, which is correct however you didn't say that it blew after you flipped the switch, rather before. If that is the case I don't see how the rectifier would have went out. Sounds to me like maybe you had a power spike that blew the fuse (especially considering you said the light went off).

[cap'n'crunch]

OK now, how about details of that sandwich?

[Gretch]

Hello All,
well, you guys definitely know your stuff!

“You have 99% likely lost the rectifier tube and probably the fuse that's in the pullout tray where you attach the mains plug”.

“Rectifier tube and the little fuse underneath your ac cable.”

I don’t know about the rectifier tube yet but the fuse is definitely blown. So I’ll go buy another fuse and hope it’ll be all I need….but I understand I only have a 1% chance that it is still working

If I need a rectifier tube, should I get the same I have or use this opportunity to get a better one? The one I currently have is a Sovtek 5AR4.

For the sandwich, well, I will unfortunately have to keep this secret for myself

[utterhack]

Unlike swapping preamp tubes, you wont really notice any difference between rectifier tubes. Any 5AR4/GZ34 will do fine once you stop whacking it with surges from the standby switch. I usually go with whatever's handy, which in my case is currently a Mesa from GC.

I'd buy another two fuses, btw... when you power-up next you'll have a golden moment when the green light starts to go on before your recto tube takes out the new fuse and everything goes dark again. Probably worth getting the tube while you're out.

[mobis8]

While I agree with utterhack in that the rectifier doesn't affect the tone, I will say I put in a 60's RCA I picked up at our local guitar show thing and it did make the amp "feel" different... maybe it is just my ears trying to justify the expense though lol... A lot of AC30 users like the new JJ stuff though fwiw...

I still don't think that the rectifier is blown though... he had it on standby when the amp stopped working...

[Gretch]

Hello All,
well, it took some time, but I was finally able to find the fuse I needed: 4 amp slow blow. Not an easy quest, I had to go in a specialized electronic shop, they don't keep these in hardware stores.

So, here's what happened. I put it the new fuse, switched on the amp, everything looked good, I could see some light in the rectifier tube warm up but it turned into a light show after maybe 5 seconds and the fuse blew (I bought a pack of 5).

So, is the conclusion that I have blown rectifier tube?

[mobis8]

wow...

sounds like it imo...

out of curiosity what position was the standby switch on when it blew? did you power it on wide open?

[Gretch]

Standby Switch was "on" (not on standby) and all knobs where turned down to "0".