dead amp.

[tinsoldier]

Hey guys! I was gigging the other night using my Orange Overdrive series 2 head when (after performing fine) it suddenly cut off. I changed leads and guitars and tried both imputs on the amp, but no signal was coming through from the amp to the lead. I tried switching the amp off to let it cool but it made no difference. Power is going into the amp as the power light and the valves light up. The only difference I can see is that all of the valves light up amber but only 3 of the 4 had a small blue glow. Does this mean that one of the valves is gone? I havent changed them since I got the amp 2 years ago. Will I need to replace all the valves or just 1? And any recommendations on where to get them or price I should be paying in UK?
Cheers!

[VintageJon]

Would check the HT fuse. You may have no B+ to the output tubes.
Worst case, you may have a failed output XFMR.

Of course it could be a preamp or inverter tube.

-Jon