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VOX AC15CC Blowing Fuses

JCMNelson
September 26th, 2009, 02:53 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, 07:18 PM
http://www.geofex.com/ampdbug/ampdebug.htm

CraigL
October 3rd, 2009, 02:50 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, 06:57 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, 09:08 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.

ThermionicScott
October 3rd, 2009, 09:36 PM
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. :shock:

- Scott

JCMNelson
October 28th, 2009, 08:02 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 :sad:

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?