[Amps] AL-1200 Intermittent HV Short

[R.Measures]

>On Mon, 8 Mar 2004 08:28:38 -0800, R. Measures wrote:
>
>>•  tnx.  Gassy tubes usually don't blow the fuse, they draw anode-I on 
>>standby. 
>
>_________________________________________________________
>
>Ok, if you say so.  My only experience with a known gassy tube was a
>3-500Z in a Heathkit SB-1000.  I powered up the amp after it had been
>sitting for about five years.  The fuse blew instantly.  I connected it
>to a variac and slowly raised the line voltage.  The tube started
>glowing a nice purple inside and was obviously gassy.
>
•  agreed.  It would have made an interesting lamp base if powered by a 
neon sign xfmr.

>My AL-1200, on the other hand, developed it's problem relatively
>overnight, so gas may not be a likely culprit.  I mentioned it only
>because of the possibility.  More likely, something internal shorted.

•  I know of another case where a 1200A7  filament shorted to the grid, 
however, 0v from grid to filament  would not cause a fuse to blow.  
>
cheers, Bill