[Amps] Alpha power down question

[Martin Sole]

Today, with KH8SI a nice signal, Murphy came to visit. The inner of the 
RCA input jack on my Alpha 78 disintegrated, age? abuse? Changed it, no 
problem but noticed something in the process.

With all tubes out of the amplifier if it is switched on and then off 
the HV discharge time is several minutes. With the tubes in, the 
discharge time is a matter of seconds, I also notice the anode current 
meter swing slightly upscale when powering off the amplifier. So, what's 
happening? Bias going down before the cathode stops emitting? Normal? 
Dangerous?

Thanks

Martin HS0ZED