Fender Dual Showman....made in 1966

[bsco]

Thank you Leo....
Cheers

[bsco]

Ok. back again....the owner had decided to order all new tubes..even a match PI tube which was gold plated....cost something like $60.....anyway. they arrived to me last week and I installed them and set up the bias......then I ran into a problem which I will post here for anybody else that might have this issue...The amp worked great but the volume would fade out to nothing...all the voltages were ok. probing the plates of the PI showed the full B+ which was way too high....so I thought the tube was bad...tested ok on my tester...anyway, when probing the grids of the PI no sound....checked the cathode voltage and there was none...so I started to check all the components in the PI area...everything tested great....so after some head scratching, I just happened to measure the voltages on the plates of the pre-amp tubes....same high voltage there as well.....it turns out the the one of the heater wires which run from the pre-amp heater string to the first output tube was corroded and produced an intermittment bad connection...and when that happened, all the heaters would go out for the pre-amp tubes....once I got that taken care of, the amp worked great....I have it re-assembled and will run it for awhile on the bench before I return it to the customer....just posting the intermittment issue here in case somebody else runs into this problem with basically any multi-tubed amp.....
Cheers

[Jazz P Bass]

I have had preamp sockets give me headaches.

The last one was the heater pins of the socket where brittle.
This was after an EL34 puked.
Probably sent B+ into the heater circuit.

[bsco]

I have had preamp sockets give me headaches.

The last one was the heater pins of the socket where brittle.
This was after an EL34 puked.
Probably sent B+ into the heater circuit.

That must have done a bit of damage.....