Rich Greenberg wrote:
In article ,
BillJ wrote:
I have Sylvania Electric tube tester. Has worked for many years, but
today known good tube test flat zero. Filaments do light. I have no
model number, it is a green panel, with roll chart.

Anybody know what might go wrong. I looked inside and see one tube, a
1EL7 I think it was. Other wise looks good, with no bad smells.

Is there a fuse? Is it good?


Yes, fuse in the A.C. line and is good. Turns on with needle at center
and line voltage setting works to put it right in center. After many
years of troubleshooting and doing restorations, this is the first time
I have looked inside a tube tester. Wow, what a wiring puzzle! I had
never thought about how they work, but guess there is actually a B+,
bias, etc applied as well as filament. Then is measures gain thru the
tube? Somehow?