Philco G978

[radiotvnut]

1. Someone might have the Sams Photofact service information that they could copy for you.

2. I'd replace the electrolytic capacitor, along with any tubular paper-style capacitors. By this time, there were many paper capacitors housed in plastic or ceramic cases. Despite the case style, they still need to be replaced. Since this is a PC board chassis, I'd remove the old capacitor can and mount the new capacitors where the old can was located. You could cut the traces leading to the old capacitor and mount new capacitors under the board; but, it might look messy. It will be neater and easier to remove the old cap and mount the new caps in it's place.

3. There are mixed opinions on rather or not to replace a currently working selenium rectifier. If you replace it with a silicon diode, you will indeed need to add a series dropping resistor to compensate for the voltage drop provided to the original selenium rectifier. In sets like this, I find that something in the 68 ohm, 2 watt range will work. However, you may have to try various values until you obtain close to the correct B+ voltage. I always install the resistor on the AC input side of the rectifier.

4. You should be able to find a polarized plug to attach to the existing line cord. There were polarized cheater cords made for TV's; but, the female end will also be polarized, making it not practical to use on this radio. In most radios, the line switch is wired in the neutral side of the line. Even with a polarized line cord, the chassis will still be "hot" when the switch is off because of the path to ground provided by the tube filament string. To get around this, the power switch should be wired into the hot side of the AC line. This way, assuming the AC outlet is wired correctly, the chassis will not be hot regardless if the radio is on or off.

5. Those FM antenna isolation capacitors are usually the ceramic disc type and are probably OK and will remain OK.

[dtvmcdonald]

Originally Posted by radiotvnut

4. You should be able to find a polarized plug to attach to the existing line cord.

OK, thanks. I can't replace just the plug, the cord itself
is falling apart and a hazard. I'll have to replace the whole
cord just keeping the socket that connects to the radio.
Did they put the switch in the neutral end so that the 115v
would not be near the volume control?

Interestingly, until about 10 years ago I actually had 110 VDC
in my office! (We had a motor-generator to make DC to run
things like big magnets. AC-DC radios worked just fine on it.
The generator is still there, turned off.)

Doug McDonald