[Boatanchors] Comet Pro Trasformer Went South (Part 2)

[Joe Connor]

Thanks for all the advice. I've run all the tests that you suggested and it appears that the power transformer is shorted.

I just want to rule out a problem with the 2.5V filament chain. The 2.5V filament secondary is center-tapped. The center-tap goes through a 450-ohm resistor to ground (bypassed by an 8 mfd cap).With the center tap disconnected, the resistance from the center tap to each 2.5V filament pin is less than 1 ohm. The resistance from the disconnected center tap to ground is 1.5 ohms. Thus, when the center-tap is connected, it is as if the 450-ohm resistor isn't even there. With the center tap disconnected, each filament pin reads 1.5 ohms to ground. Is that another problem?

To avoid confusion, the schematic can be found here http://www.nostalgiaair.org/PagesByModel/994/M0008994.pdf  at Hammarlund 3-2.

Thanks.

                              
                    Joe Connor