LSS Sound cut out, then smoke, then nothing (fuse blown).

[WantaMKIV!]

I'm not technical at all and have never had a valve amp do this (never had one breakdown come to think, lucky me!). Before I pay for a techie to investigate i thought I'd ask you guys.

When I replaced the fuse, it seemed ok on standby (lights on, no smoke!), switched 'on', fuse blew (no smoke). Is this simply a valve issue i.e. replace them? Any guidance or tests appreciated.

Cheers, Tim

 

[plan-x]

Try it again but this time watch the tubes for any unusual arcing in that moment before the fuse goes. The smoking may/may not be of permanent damage. Cross your fingers.

 

[Sebber]

This happened to my LSS after I'd had it for six months: the burning smell was the power transformer (the one on the left hand side as you look at the amp from the back), which fried.

 

[WantaMKIV!]

Thanks for the info, tube no 3 offered some pretty lights and fizz for a second then the fuse went so I'm hoping that's all it is. How good am I?, no spare tubes :roll: !! Over confidence of running a dual amp set up I guess. I'll let you know the outcome once the new tubes arrive.


Thanks again.

 

[screamingdaisy]

Sounds like a failed power tube. The smoke may have been the screen resistor frying. Not a big deal as they go all the time when a tube fails, but it is kind of a pain in the *** when it happens.

 

[WantaMKIV!]

If the screen resistor is 'fried', will my new tube get screwed when I put it in, they arrive tomorrow (matched quad set), can I put one of the others in and leave an empty socket for a few moments and check. ****, I know nothing!!!

 

[plan-x]

Yes, it could damage a new/good tube. Where was the bad tube? inner pair or outside pair. Your amp may work right now if you can get the good tubes to the outer pair which is the 50w pair and switch to 50w mode. That will help figure out if the resistors are still in tact. Or you could take the amp a part and look at them, they will be visibly damaged. There is some good info here w/pics in this (Lonestar) sub forum topic. A seach of "screen" should do the job. I replaced mine. But at a price, that story is in here also.

 

[WantaMKIV!]

Cheers Big Blue

Checked inside, no burn marks of any sort. New tubes in, sounds amazing.
Thanks again, Tim

 

[plan-x]

Yay!