09-24-2013, 07:09 PM
I have an Atwater Kent 328 (early) Rider 6-18 for the schematic and 7-34 (bottom) for chassis layout. http://www.nostalgiaair.org/PagesByModel...001334.pdf
I think I have a bad power transformer but want to be sure so here is what I have done.
Recapped, changed some out of spec resistors and rewired the Selective Fidelity Switch back to original and replaced the 5Z4 tube, got the tuner mechanism working, had to find a speaker and output transformer which I did I'm 250ohms light on the field coil and use a resistor to bring it up.
When I powered up it started drawing high current 1amp at 15v(I use a varac with a digital meter set to read amperage) so I backed it down and tried it with all tubes removed, same thing. I pulled the transformer and powered it up and on the plate leads I got 700vac and 350 & 345vac each side to the center tap.5.3vac for the 5Z4 heater and 6.3 for the tube heaters and dial lamps current was minimal (.o6-7). That looked good so I reinstalled and still had high current draw I stop at 1amp but I'm only at 15v so I disconnected the leads one set at a time and when I disconnected the center tap things got better but still high about 1.7amps but at 110v the set says 90watts so I figure around 1 amp or less I don't leave it on for long as I don't want to damage anything not sure what the effect of leaving the center tap open? Checked R26 and it is good and c27 has the +on the white and the - to the center tap
I did get some stations briefly then faded out.
Any Ideas?
Thanks Eric
I think I have a bad power transformer but want to be sure so here is what I have done.
Recapped, changed some out of spec resistors and rewired the Selective Fidelity Switch back to original and replaced the 5Z4 tube, got the tuner mechanism working, had to find a speaker and output transformer which I did I'm 250ohms light on the field coil and use a resistor to bring it up.
When I powered up it started drawing high current 1amp at 15v(I use a varac with a digital meter set to read amperage) so I backed it down and tried it with all tubes removed, same thing. I pulled the transformer and powered it up and on the plate leads I got 700vac and 350 & 345vac each side to the center tap.5.3vac for the 5Z4 heater and 6.3 for the tube heaters and dial lamps current was minimal (.o6-7). That looked good so I reinstalled and still had high current draw I stop at 1amp but I'm only at 15v so I disconnected the leads one set at a time and when I disconnected the center tap things got better but still high about 1.7amps but at 110v the set says 90watts so I figure around 1 amp or less I don't leave it on for long as I don't want to damage anything not sure what the effect of leaving the center tap open? Checked R26 and it is good and c27 has the +on the white and the - to the center tap
I did get some stations briefly then faded out.
Any Ideas?
Thanks Eric
