Smoking Joe 2 start up issues

[Alby]

I have had this one half built on my bench for over a year now and finally got around to finishing it off. It's a homebrew SJ2 using the Weber schem. but with a Hammond 290BX transformer and a 5Y3 rectifier insted of diodes. I have been out of building for a while now so my troubleshooting skills have faded with time and was hoping for some assistance.

The obvious : Nothing blew up!
No guitar sound.
Slow motorboating sound from the speaker. Varies speed by turning MV pot.
Voltages are way too high. At 'C' i'm getting over 400 volts.

I am thinking the motorboating may be caused by the high voltages causing instability in the circuit and I have hooked it all up correctly. Visual inspection is very difficult due to the small box and stacked turret boards just like in the Weber version.
If anyone can offer up the expected voltages I should expect to see based on the Weber kit that would be helpful.


I also posted this on the Weber forum.

[MWJB]

You say voltages are too high...400vdc on the power tube plates sounds about right for a 290BX, but if you have used a 130ohm cathode resistor for the EL84 then this value is too small for these voltages (your tubes my be dead)...get a 50W 50v reverse polarity zener diode to bring the voltage down (insert between B+ centre tap & ground).

Whwn you have this installed fire it up & list dc voltages for power tube plates, screens & cathodes, preamp plates & cathodes.