Vox Ac15hw no sound

Macca_25387

Don’t suppose anyone could shed light on this for me.
Changed all the valves last week with a full kit from Watford valves, worked perfect. 
Come back to rehearse tonight everything is lit up but no sound not even a hiss. 
I’m baffled. Have i missed something?

ecc83

HT fuse? 250mA T AFAICT. Fit one, if it holds fine. If it blows, tech time but you could have a buggered rectifier valve or power valve.

Dave.

Macca_25387

i’ll look at that. All the valves are lit when it’s switched on. I’d be more baffled if it never ran when i first changed all the valves. 

DJH83004

As Dave has said, there is a T250mA HT fuse (on the same side of the chassis as the valve bases). There is also a 6.3amp heater fuse, but clearly that is intact as the heaters are lit. I suspect one of your new output valves may have gone internal short - this can happen even with brand valves I'm afraid.   

Pablocrackers

Definitely not the speaker wire come away from the speaker? And hooked up?

ICBM

It's quite common for a new valve to fail shortly after fitting - if it blows the HT fuse the valves will light up but the amp won't work. Check the speaker connection first as Pablocrackers said, but if it's not that it's almost certainly one of the power valves or the rectifier.

If you have spare fuses you can usually identify which one by re-substituting the old valves one at a time and watching the valves carefully as you switch on.

Macca_25387

Very helpful guys. I’ve still got the valves i took out. I shall report back. 

Dominic

speaker connection

prlgmnr

Everyone came in here expecting this to start "So I just picked up this bargain AC15 from Guitarguitar", right?

kreggs

prlgmnr said:

Everyone came in here expecting this to start "So I just picked up this bargain AC15 from Guitarguitar", right?

Haha yes, first thing I thought

Macca_25387

Haha, if it’s any consolation i did originally buy it from GuitarGuitar. An i did go back after 6 months for a fault. I’ve had a few years loving it since then. Well untill...

Cirrus

Yeah, check the HT fuse. Sometimes they just blow - those HW AC15s & 30s run really hot, right on the edge, and the fuse can go "just because".


My HW30 once went completely silent because a resistor blew, but that was preceded by some pretty strange UFO noises so it's probably not that.

Macca_25387

The culprit was one of the preamp valves, didn’t recognise it was bust at first as it has a metal sleeve covering it. As soon as i removed that you could see it had gone. Shot the old one back in and it’s away again. Thanks for the advice gents.