[MrFixr55]

Hi Philco,

Progress! Great! The pilot lamp won't make a difference in whether or not the tubes light up as it is a standard 7 Watt 120 Volt night light bulb. However, having it in may be of diagnostic help.

Don't worry about the safety caps, leave them out for now. The purpose of these safety caps is to filter out any interference on the power line to the radio or any interference generated by the radio from entering the power line. The reason why they are called safety caps is that they are not supposed to short or overheat when across a power line. Having been bitten by a chassis that went hot, I can tell you that the original EMI filter caps were not safety caps. The radio will work without them.

For the next phase of testing, you will need to be taking measurements on a live radio. REMEMBER SAFETY. REMEMBER THAT THIS IS A HOT CHASSIS! Use the "one hand in your pocket" technique. In other words, to prevent a dangerous shock, wear non-conductive rubber soled shoes, sit on a non metallic chair. If you have not reconnected the rectifier wires, do this. If you replaced the rectifier, it is important that the side of the rectifier with the band (the cathode) be connected to the 22 Ohm resistor and the other lead goes to power.

Using an alligator clip, clip one lead to the chassis. Set the meter to AC, and with the radio power switch on and the radio plugged in, measure between the chassis and a known ground. The voltage should be essentially zero volts. If it is 120 V, reverse the plug. At this point, the pilot light should be lit. If so, you have power to the radio. If not, disconnect power and check the power switch. If you tripped the breaker testing the radio, the current that passed through the power switch may have been enough to blow it. With the radio unplugged, measuring across the power switch, you should read close to 0.00 Ohms. The meter should display a number, not "OL". If you read OL, then "jumper out" the switch so it is permanently on. The pilot light should light and if the tubes are all installed, they should light. If all else is well, you should get sound. If no sound and /or the tubes don't light, set the meter to DC and measure the cathode side of the rectifier, which connects to the 22 Ohm resistor. You should read at least 120V and likely much higher. If this passes and the tubes are not lit, it is because a tube is burned out. If all were well, each tube will have a voltage drop across its filament equal to the correct voltage of the filament. Think of a set of Christmas Tree lights. For example, a 50C5 will have a 50V voltage drop between pins 3 and 4 if it were lit. The 19C8 would have 19V across pins 4 and 5. The other tubes would have 12V across pins 3 and 4 except the 12AT7 which will have 12V across pins 4 and 5.

Set the meter to AC Volts, and with one lead still clipped to the chassis, use the schematic, and measure pin 3 and pin 4 of the 50C5. You should read 120V on both pins. If you read 120V on pin 3 of the 50C5 but 0V on Pin 4, then the filament of the 50C5 is burned out. If you read 0 Volts on both pins, you still have a wiring issue. If 120V on both pins 3 and 4, go to the next tube, the 12AT7 and measure pins 4 and 5. You should see 120V on both pins. If 120 V on one pin and 0V on the other pin, then that tube has an open filament. Keep working down the "string" in the order as listed on the schematic. When you find the tube that reads 120 on one pin and zero on the other, that tube has an "open" (burned out) filament.

To make things more complex, look at the bottom of the schematic where it shows the filament string. You will note that there are chokes in each side of the 12AT7 filament. In addition, there are several capacitors between various tube filaments and chassis ground. If the chock is burned out (open), this will cause the tubes to not light. If any of the capacitors are shorted, especially the one between the 50C5 and ground, it will burn out one or more tubes between the shorted cap and the source of power.

I know that this is complicated but do it one step at a time. Anything complex is made up of simple things. You cleared the short, now continue and find out why the tubeds don't light, using the above instructions in the order that I listed.

Do not be afraid to help, remember SAFETY, ask questions. We are happy to help you score a big success with this one.