08-12-2015, 06:34 PM
http://www.nostalgiaair.org/pagesbymodel...013838.pdf
I finally have gotten serious about that Philco 77 (busy Summer what with trips to take and somehow four other radios got in line before it), but after restuffing the bakelite boxes and the small metal cap boxes and the large cap box, recapping the tone control, AND replacing all of the resistors with 1 watt new ones, it failed a dim bulb test.
Measuring the resistance on the power transformer, I find low resistance on the primary (about 20 or a bit more-going on memory here), VERY low resistance (0.1-0.2 ohms) on the filament secondary for the 80 (10 & 11), and on the ones for the 45s (7 & 8) and 24As & 27 (5 & 6). Under 300 ohms on the HV winding (9 & 12).
The wire-wound resistors measure as they should, and I've triple-checked the large cap box hook-up. The choke and the output transformer and the field coil all measure as they should.
I guess my question is: Should I be seeing higher numbers on the various filament windings, or are these numbers about right, AND if these numbers are about right, I should be looking for a short further down the line, right?
I have yet to try powering it up with no tubes, but I guess that is next?
UPDATE: when I tried bringing the transformer up with no tubes in it and a dim bulb (15 watts) in series with my variac, I bee a faints glow around 70 volts and a soft glow at 110 volts. I guess that qualifies as a shorted transformer?
I finally have gotten serious about that Philco 77 (busy Summer what with trips to take and somehow four other radios got in line before it), but after restuffing the bakelite boxes and the small metal cap boxes and the large cap box, recapping the tone control, AND replacing all of the resistors with 1 watt new ones, it failed a dim bulb test.
Measuring the resistance on the power transformer, I find low resistance on the primary (about 20 or a bit more-going on memory here), VERY low resistance (0.1-0.2 ohms) on the filament secondary for the 80 (10 & 11), and on the ones for the 45s (7 & 8) and 24As & 27 (5 & 6). Under 300 ohms on the HV winding (9 & 12).
The wire-wound resistors measure as they should, and I've triple-checked the large cap box hook-up. The choke and the output transformer and the field coil all measure as they should.
I guess my question is: Should I be seeing higher numbers on the various filament windings, or are these numbers about right, AND if these numbers are about right, I should be looking for a short further down the line, right?
I have yet to try powering it up with no tubes, but I guess that is next?
UPDATE: when I tried bringing the transformer up with no tubes in it and a dim bulb (15 watts) in series with my variac, I bee a faints glow around 70 volts and a soft glow at 110 volts. I guess that qualifies as a shorted transformer?
Charlie in San Antonio
