>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.
This does not explain heater burnout because insufficient warm-up can
result only in cathode flaking. Did you perform the Funderberg loose
gold test? Would you sell me the kaput tubes?
>
cheerz, Bob
- R. L. Measures, a.k.a. Rich..., 805.386.3734,AG6K,
www.vcnet.com/measures.
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