I just modded a Showman( was a basket case) used individual 500 ohm 10w bias resistors and individual 25uf caps across each one. Sounds Great. Tubes are running cool .
If the 6.3VAC filament winding does not have a CT, then you need the two resistors, one from each side of the winding to ground, to create an artificial CT. They are typically 100 ohm.
Thank you Martin,The transformer has a center tap.These values on the board are kinda hard to find 22uf/63 and 22uf /40.can they be subed for say a 25/50,then on the rectifier there is this 0.01 3kv,what is that?and I believe I will have to get a 270/20 watt.I have to do something diff at the end of the board for bias,correct?I'm going very slow here most of you guys would be done in a day or so. So if you guys can direct me to some of these diff value parts that would be great,Mikey
Thanks Mark,would you sub the 22/63 with the 25/50"s it would be nice just to get all three one shot.I want to get some good pots as wellThat one cap I assume on the rec tube pins 4&6 by the diodes.what is a 0.01 uf 3 v ,what's the 3v?Is that just 3 volts?
ampmike wrote:Thanks Mark,would you sub the 22/63 with the 25/50"s it would be nice just to get all three one shot.I want to get some good pots as wellThat one cap I assume on the rec tube pins 4&6 by the diodes.what is a 0.01 uf 3 v ,what's the 3v?Is that just 3 volts?
The 22 vs. 25uF is no big deal, either one will do. The silicon diodes are backing up the vacuum diodes, and the cap is across the AC presumably to eliminate switching noise. It's shown as a 3kV rated part, but 2kV would be enough. There is an error on the Ceriatone layout in that the DC feed to the reservoir cap should come from pin 8.