I am attempting to repair a Henry 3kA console with a pair of 3-500Z's for a
friend. Only the left side tube's filament is lighting. The right side is
Doing an A/B swap still results in the right side not lighting. Pulling the
right (unlit) tube, the left tube still lights.
After pulling the tubes, I inspected the tube sockets. All looks OK. I took
some measurements with an ohmmeter, and pin5 of left tube has a good
connection to pin1 of right tube. Pin1 of the left tube and Pin5 of the right
tube have good continuity to the filament transformer. I measured less than
10 ohms on the secondary of the filament transformer when totally
disconnected via the jones connection. My next step is to wire the meter to
each socket and take some voltage measurements with power applied. Stopped
short there last night as I was getting too tired and didn't feel like making
a deadly mistake due to fatigue.
Before I dig deeper and pull the RF deck off the console for further
inspection (the tube socket base assy is a bear to get to!), does anyone have
any suggestions ?
Is it possible for the one tube to light without the other tube in place
(like the old christmas lights where one bulb out causes the rest to go out)
? It appears they are wired in series, but is it possible the transformer has
an opening on one side of the secondary, and I am getting a return to ground
via another path? (I checked the caps to ground from the fil. pins, and all
are ok) Gave up last night, maybe I am missing something too obvious ??
TIA for any suggestions.
KK2ED (ex ka2ykc)
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