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HI everyone

Was playing with my amp à low volume.... hten it sudenly fade the now there no more sound of it.

tube are lighting... tranny are not hot..

Hope it not the patridge

what can I do ?

Did you check the HT fuse? That fuse only interrupts the high voltage, the tubes and indicator will still light if it is blown.
http://hiwatt.org/tech.html

On very rare occasions, this fuse will fail due to age & vibration, but it most often indicates a bad output tube (EL34). If the fuse is blown, replace it, but watch the EL34s when you turn it on again. One may be red-plating (the tube structure itself starts glowing a dull red, different from the bright orange heaters). This condition somestimes causes extra hum from the speakers, but otherwise there's no audible indication.

If a tube did red-plate for a while, it may be permanently damaged, i.e., the HT fuse will blow again quickly.

In any case, I suggest you remove the chassis and inspect the output tube sockets for any sign of overheating or charring. There is a small resistor connected to the socket that typically burns/turns black when an output fails catastrophically.

thanks !

Ht fuse is ok, therefor tube are red plating ( mullards XF2 ) ...

my be a problem with the bias...bias cap is original...

Are you sure the fuse is OK? Sometimes (particularly with vibration failure) the fuse looks perfectly fine, but measures open.

Fuse have been tested ok

Could it be a préam tube? PI?

Amp is working again !

There was just a broken wire ... the HT1 connexion to the output tranny. HERE




I wonder how this happen

Thanks.

I'm glad you found it, and that it was a simple fix.