Valve amp help needed

[Voltij7]

Hi I have a Conrad Johnson Premier 140 which was in a house fire. The amp whilst sooty appears unscathed apart from one o/p tube (KT120) which has a cracked envelope and is obviously useless. I gave it a clean up and decided to try a power up with the o/p tubes removed, I suspect that was a silly idea as the plate fuses immediately blew. Not sure what to do next maybe try a power up with the KT120s in place or find someone in Sussex or the south to have a look. What do you think can anyone help or recommend an expert?
Thanks S

 

[rabski]

It's far from ideal to run any valve amp with the valves removed, as without any load, some of the voltages can rise way above safe levels for components. A bit late now, but for the future also bear in mind that you should never, ever run a valve power amp without speaker load connected, as you can potentially fry a lot more.

I have no idea how full of work he is, but our Henry (@toprepairman ) is I believe not too far from you and knows his valve onions.

 

[Jazid]

I have some small and regrettable experience with this amp, mostly because it runs voltages *hard on* upper valve specs if I'm being polite. Without valves the voltages will be even higher. Definitely not one to mess with.

As Rabski suggests, Henry is your man, if he's too busy there's David Coe (Juancho) in Wimbledon who also does this stuff.

As far as I can tell, without output valves the plate fuses (F6 and F7) shouldn't be in any danger of blowing since they've got no load on them, so I'd suggest there might be rather more wrong in there than just a couple of shagged fuses.

Good luck!

 

[Voltij7]

I have some small and regrettable experience with this amp, mostly because it runs voltages *hard on* upper valve specs if I'm being polite. Without valves the voltages will be even higher. Definitely not one to mess with.

As Rabski suggests, Henry is your man, if he's too busy there's David Coe (Juancho) in Wimbledon who also does this stuff.

As far as I can tell, without output valves the plate fuses (F6 and F7) shouldn't be in any danger of blowing since they've got no load on them, so I'd suggest there might be rather more wrong in there than just a couple of shagged fuses.

Good luck!

My bad, further investigation reveals neither the plate fuses nor the mains fuse is blown don't know whether this is good or bad S

 

[rabski]

My bad, further investigation reveals neither the plate fuses nor the mains fuse is blown don't know whether this is good or bad S

The answer is 'either' (possibly good, possibly bad). Without testing and checking, it's anyone's guess.

Sensible advice would be to get it to someone who knows valve stuff and let them test it properly.

 

[Radford Revival]

Plate fuses blowing without output valves installed is somewhat concerning. If the amplifier is fairly conventional that implies with no valves installed there should be no way for there to be any current to ground through the output transformers aside from leakage (nA-uA). I wonder if there's still some soot somewhere shorting something.

 

[Voltij7]

Plate fuses blowing without output valves installed is somewhat concerning. If the amplifier is fairly conventional that implies with no valves installed there should be no way for there to be any current to ground through the output transformers aside from leakage (nA-uA). I wonder if there's still some soot somewhere shorting something.

Not sure what to do with this now.
I'm wondering if it might be best to sell it as is, to someone with the knowledge to check it out and/or fix it.
Cosmetically its in good shape but does need a good clean and it has seven lightly used KT120 which are not cheap plus the small tubes.
I even still have the original box and manual.
What do people think?
Anyone interested.