VOX AC15CC Blowing Fuses

JCMNelson · September 26th, 2009, 03:53 PM

My Vox AC15 has always worked great and hasn't been modified in any way. 2 Years ago I replaced the valves, and the 'new' ones have sounded great!

I played it a few nights ago for an hour or so, and everything was fine. Now it's just blowing fuses. It wouldn't power up at band prac and I figured it was prob a fuse that had gone. Got new ones today (T800, 250V) and the power light comes on for half a second before dying.

I've removed all tubes and tried, but it's doing the same.

HELP!!! I've done some work on amps and know how to discharge filter caps etc, where do I start with this?

Wayne Alexander · September 26th, 2009, 08:18 PM

http://www.geofex.com/ampdbug/ampdebug.htm

CraigL · October 3rd, 2009, 03:50 PM

I had the same thing happen with my 2000 AC30 reissue and it was the rectifier tube. I replaced that and then no more problems.

insombob · October 3rd, 2009, 07:57 PM

me too with my '96 ac30. cheap chinese rectifier tube kept arcing every once in a while when i'd push it with a fuzzbox. hardest thing to locate until i brought all the gear down to the shop and played for a while. i'd swap out the rectifier first and see if that solves it.

Wayne Alexander · October 3rd, 2009, 10:08 PM

The AC15CC does not have a tube rectifier. First thing to suspect is bad power tubes, second thing to suspect is bad preamp tubes. So swap the power tubes to good new ones, and if that wasn't it swap the preamp tubes to good new ones. If you don't know what to do if that doesn't fix it, take it to a tech. Blowing fuses is never caused by a weak fuse, something is drawing too much current.

Scott S · October 3rd, 2009, 10:36 PM

Quote:

Originally Posted by JCMNelson

Got new ones today (T800, 250V) and the power light comes on for half a second before dying.

I've removed all tubes and tried, but it's doing the same.

I'd take it to a tech at this point.

- Scott

JCMNelson · October 28th, 2009, 09:02 AM

So, I sent the amp to a tech and he found a short-circuit. Turns out that legs of two components were protuding so far through the pcb that they were touching the chassis!!!!! He thinks that they weren't originally touching, but that the board has lost a bit of rigidity of the years.

So, short circuit fixed, BUT it's damaged my PT

I'm going to replace it but I'm trying hard not to use a Vox part as I've heard that there have been a few faulty ones around. It's not easy to get alternatives in the UK, anyone got suggestions?

September 26th, 2009, 03:53 PM	#1 (permalink)
JCMNelson TDPRI Member Join Date: Jul 2009 Location: London Age: 34 Posts: 27	VOX AC15CC Blowing Fuses My Vox AC15 has always worked great and hasn't been modified in any way. 2 Years ago I replaced the valves, and the 'new' ones have sounded great! I played it a few nights ago for an hour or so, and everything was fine. Now it's just blowing fuses. It wouldn't power up at band prac and I figured it was prob a fuse that had gone. Got new ones today (T800, 250V) and the power light comes on for half a second before dying. I've removed all tubes and tried, but it's doing the same. HELP!!! I've done some work on amps and know how to discharge filter caps etc, where do I start with this?

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Twin Reverb RI blowing fuses	RotelliCaster	Amp Central Station	21	May 20th, 2009 04:57 PM
Bassman RI blowing fuses	Del Pickup	Amp Central Station	26	June 26th, 2008 04:40 AM
new 5F1 blowing fuses	TelZilla	Amp Central Station	6	April 9th, 2008 02:31 PM
New AC30 CC1 blowing fuses	Chris Truman	Amp Central Station	3	April 22nd, 2006 01:07 AM
Carmen Ghia keeps blowing fuses	Dana	Amp Central Station	11	December 14th, 2004 06:12 PM

September 26th, 2009, 08:18 PM	#2 (permalink)
Wayne Alexander Tele-Afflicted Join Date: Mar 2003 Location: Los Angeles, CA, USA Posts: 1,351	http://www.geofex.com/ampdbug/ampdebug.htm

October 3rd, 2009, 03:50 PM	#3 (permalink)
CraigL TDPRI Member Join Date: Mar 2003 Location: Livermore, California Posts: 71	I had the same thing happen with my 2000 AC30 reissue and it was the rectifier tube. I replaced that and then no more problems.

October 3rd, 2009, 07:57 PM	#4 (permalink)
insombob TDPRI Member Join Date: Sep 2003 Posts: 97	me too with my '96 ac30. cheap chinese rectifier tube kept arcing every once in a while when i'd push it with a fuzzbox. hardest thing to locate until i brought all the gear down to the shop and played for a while. i'd swap out the rectifier first and see if that solves it.

October 3rd, 2009, 10:08 PM	#5 (permalink)
Wayne Alexander Tele-Afflicted Join Date: Mar 2003 Location: Los Angeles, CA, USA Posts: 1,351	The AC15CC does not have a tube rectifier. First thing to suspect is bad power tubes, second thing to suspect is bad preamp tubes. So swap the power tubes to good new ones, and if that wasn't it swap the preamp tubes to good new ones. If you don't know what to do if that doesn't fix it, take it to a tech. Blowing fuses is never caused by a weak fuse, something is drawing too much current.

October 28th, 2009, 09:02 AM	#7 (permalink)
JCMNelson TDPRI Member Join Date: Jul 2009 Location: London Age: 34 Posts: 27	So, I sent the amp to a tech and he found a short-circuit. Turns out that legs of two components were protuding so far through the pcb that they were touching the chassis!!!!! He thinks that they weren't originally touching, but that the board has lost a bit of rigidity of the years. So, short circuit fixed, BUT it's damaged my PT I'm going to replace it but I'm trying hard not to use a Vox part as I've heard that there have been a few faulty ones around. It's not easy to get alternatives in the UK, anyone got suggestions?

IMPORTANT:Treat everyone here with respect, no matter how difficult! No sex, drug, political, religion or hate discussion permitted here.