negative voltage on screen

John W. King jbkking at BELLSOUTH.NET
Tue Jan 2 14:05:59 EST 1996

Have been making measurements on my valiant 1 that has negative grid
current reading on grid drive. FOUND that the screens of the 6146 final
tubes have about -58 volts d.c. NEGATIVE instead of the 152 volts d.c.
positive that is supposed to be on them. This condition exists with and
without the final tubes in their sockets. Checked the 6AQ5 clamper tube
and it checks good without shorts. The negative bias on the grids of the
final tubes is within normal parameters. The low voltage power supply is
cranking out +300 volts as it should. I must find out why the final
tubes have negative voltage on the screens. Any suggestions?
Something has gone belly up to have negative voltage on the screens
instead of positive voltage. Thanks for taking a look at your
schematics. 73, John, K5PGW

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