Type CA module in a 545

David Kuhn

Hello all,

Type CA. All tube sockets cleaned, switches cleaned and the two pots that
can be clean are cleaned.

10volts will only read as 8 volts on either channel.

I swapped the output tube (common to both channels) V383A, 12AT7, with the
multivibrator output tube V3393. Same issue, not enough overall gain, in
both channels.

I haven't quite figured out how that module works. Apparently the
multibrator supplies power to the plates of both channel amplifier tubes
via V3393A. That was one I swapped. I am thinking that V3393A may not be
turning on hard enough, but I am really clueless with this module.

Is there a common issue with the Type CA that causes overall low gain on
both channels? When I install my Type D or Type 53/54K, both are bang-on,
but there doesn't appear to be any head-room to spare. So maybe the scope
needs a gain adjustment?

Thanks for the thoughts and idears....

Join TekScopes@groups.io to automatically receive all group messages.