[Amps] ALPHA 77 SX STATUS

[K8MLM@aol.com]

I got the ALPHA 77 SX up and running.  

Problems were:  Both tube filaments burnt out, electronic bias was not 
working properly, and warm-up timer running too fast.  

The fix; two new tubes, removed a number of modifications someone made to the 
bias system circuit board and brought the board up to date with the latest 
board design .... Added a bias threshold pot.  Electronic bias now operating 
correctly.  The warm-up timer was also running fast ... about 1 minutes and 
30 seconds rather than 3 minutes.  

Bottom line, the amp was going to the 8.1 vdc operating bias after 1 minute 
30 seconds ... the tubes experienced loading before proper filament warm up 
resulting in the tubes' premature filament burn out.

73,

Bob

K8MLM