Hi all i have a Denon DRA 455 with Eltax Linear 6.5 wich is 8ohms i have a sub but no sub output, apart from sharing power between them, how can i hook these up please? thanks

zone 2 is just for an extra set of speakers in another location, your sub is not attatched to that zone

Output transister is fried,

Generally speaking, an amp attempts to protect itself from heat, shorts, overloads and operator exuberance by refusing to turn on or stay on.

Overloads can be from excessive periods of high output or marginally low impedance loading by the speakers; and shorts would be wiring issues or a speaker blowing up.

You should be able to feel if it's hot. WHY is it overheating? Make sure it has sufficient ventilation on all sides and that vent holes are not blocked by dust balls. Ensure the fan (if equipped) is running as designed (some only operate on demand). Clean dust and debris from it.

If the amp comes back on after cooling, you're lucky. They only have so many self-protection cycles in their lives so continuously resetting or cycling their power without addressing the cause can do more harm than good.

If it protects immediately on a cool power up you should disconnect the speaker connections and try it '*****'. If it comes up then diagnose which lead(s) are shorted. If it does not come up the problem is internal and should be left to an experienced and competent hands-on tech.

Sounds like this is a powered subwoofer (as it has a line input). If this is the case, the 'sub W' output of the receiver will NOT work, as it is only sending speaker level to the line input.

You will likely go from sub W directly into the speaker input on the sub. The output is probably used for looping an additional sub into the system.

It really depends what and how much burn't up? The only way to find out it to take the top cover off and look inside. A lot of parts in the power supply section can only be replaced by excat parts due to safety reasons. And are you certain it's the power supply that's gone up, and not the POWER AMP section? It could be just one part that started smoking. If any semi-conductor has burnt up, you might not be able to read the code number, in which case you will need the service manual.
SO GET LOOKING INSIDE!

Problems of this nature are often caused by electrolytic coupling capacitors. If you have access to an audio signal generator. Inject signal at volume control and compare left and right output levels. This will isolate fault to pre amp stage or power output stage. freezer can be very usefull in isolating this type of fault.

is the sub in speaker set A and sub in set B?
that was my problem on Denon DRA-455 with Eltax Linear 6.5

I have traced the fault to the rf amplfier transistor in the tuner "can" It is a 4 pin item with 6JK85 on the encapsulation but have been unable to source a replacement. Can anyone help?

Most probably the memory capacitor / battery inside soldered to pcb

Hey Skyworth
If you had a meter, I could have talked you through making a few diagnostic tests. Get back to me here with a comment if you want to have a go:)

regards
Graeme