[Ron Ramirez]

I'm still plugging away on this chassis...

The rewiring is nearly complete. See below:

[Image: http://www.philcoradio.com/images/phorum...T2_046.jpg]

I took some time today to calculate the wattages of the resistors needed to replace the five-section Candohm. With the help of the RCA service info, I was easily able to do this. Here's how:

The schematic gives the resistances of the five sections.

From the voltage drawing (page 7 of the PDF manual linked above), I was able to find all but one of the voltages - and that was at the junction of the 3500 ohm and 13,000 ohm sections. To find that, I simply did some math.

The 3500 ohm and 13,000 ohm section together drop 258.8 volts.

Ohm's law gives us the rest:

3500 + 13,000 = 16,500 ohms

I = E / R, so to find total current through the two sections: I = 258.8 / 16500 = 0.016 A (16 mA)

Now, to find the missing voltage:

E = I * R = 0.016 * 13000 = 208 V

Here's a drawing.

[Image: http://www.philcoradio.com/images/phorum...T2_047.jpg]

Now, we use the formula P = I squared * R to find the necessary wattage. (You can also use P = I * E .)

But first we have to figure out the currents involved.

3500 ohms - 52 volt drop = I = E / R = 52 / 3500 = 0.016 A

So, 0.016 * 52 = 0.832 watt

You want to double this figure for safety, so the 3500 ohm resistor needs to be 2 watts.

Let's do the same for the rest.

13,000 ohms, 0.016 A, 208 volt drop so 0.016 * 208 = 3.328 so the 13K needs to be at least 7 watts.

85 ohms, 0.014 A, 1.2 volt drop so 0.014 * 1.2 = 0.0168 so a 1/2 watt resistor is fine for the 85 ohm section.

40 ohms, 0.075 A, 3V drop so 0.075 * 3 = 0.225 so, again, a 1/2 watt resistor may be used for the 40 ohm section.

175 ohms, 0.074 A, 13V drop so 0.074 * 13 = 0.962 so the 175 ohm resistor should be at least 2 watts.

With that information, I know what I need to order.

Here is another under-chassis drawing. You can see that more of the lines are highlighted...

[Image: http://www.philcoradio.com/images/phorum...T2_048.jpg]

I did not highlight all of the power transformer and filament leads. These, with the exception of the 115 volt primary leads, have not been disconnected and remain in place.